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May 31, 2003
SARS crisis curbs ophthalmic surgery as hospitals shut down
Eurotimes May 2003
Near the end of March, all hospitals in the greater Toronto area were ordered to suspend non-essential services, including non-urgent ophthalmic procedures. Ophthalmologists are worried about their practices and not being able to see patients. Those who have their offices inside the hospitals are scrambling to be able to work in some of the community offices.Overall, delayed surgeries and the postponement of other procedures are putting a huge strain on an already overburdened health care system, he added.The hospital was temporarily closed to new patients on March 23 by the Ministry of Health after two SARS patients died. People who had contact with the patients including hospital staff, other patients and visitors have been put into voluntary home quarantine.In some ways, ophthalmology hasn’t been hit as hard as other medical specialties like cardiology
EMKH
Posted by alireza habibollahi at 11:55 PM
High-frequency ultrasonography clears up old misconceptions on phakic IOL sizing
According to ultrasound analysis of postmortem specimens, the eye is not perfectly round, and white-to-white measurements are unreliable.
OSN May2003
ROME – Evaluation of the geometry of the anterior chamber and ciliary sulcus using a high-frequency ultrasound system demonstrated that the eye is not geometrically round, as the measurements taken at different meridians do not coincide.“Although the difference between meridians is relatively small, it may be significant enough to explain the postoperative rotation we can observe with some phakic IOLs. It is also important to evaluate if these differences are significant enough to be taken into account by IOL manufacturers to improve the design and sizing of phakic IOLs.A second important finding, confirming the result of other studies on this subject, was the lack of correlation between ultrasound sizing of the anterior chamber and ciliary sulcus diameter and the white-to-white measurement based on empiric formulas.Also, when we looked at the correlation between the white-to-white and the anterior chamber and ciliary sulcus diameters, we found a positive correlation in this series between the white-to-white and the anterior chamber diameter only in the vertical meridian. We couldn’t find the same correlation in the horizontal meridian, and there was no correlation at all between white-to-white and ciliary sulcus diameter in either the vertical or horizontal meridian,” she said.However, the study suggests that the human eye is not perfectly round, and that the traditional methods used so far for IOL sizing are grossly inaccurate, two crucial aspects we have not been fully aware of for so many years, she added.Finally, we believe the ultrasound system used is a valuable means of IOL sizing, as it provides accurate, objective measurements of the internal diameters of the eye. Another advantage is that it is also noninvasive, and measurements are taken preoperatively, giving time for a careful evaluation of the size and type of IOL to be used for each patient.
Posted by mehdi khanlari at 10:45 PM
VisThesia
OSN May 2003
VisThesia (CIBA Vision Surgical, Switzerland) offers a new approach to cataract surgery by combining viscoelastic and anesthetic, which may help surgeons reduce the time required to perform cataract surgery and increase patient comfort during the procedure.VisThesia consists of a topical component and an intracameral component. The topical component is a mixture of 0.3% sodium hyaluronate and 2% lidocaine hydrochloride, and is used preoperatively, while the intracameral component is composed of 1.5% sodium hyaluronate and 1% lidocaine hydrochloride, and is used perioperatively.Researchers have evaluated the VisThesia intracameral component in an in vitro animal study.1-3Histological evaluation of the retinal and uveal tissues showed no differences between the eyes receiving VisThesia injections compared to eyes in the control group receiving balanced salt solution (BSS). There also was no histological evidence of endothelial damage or endothelial cell loss observed.Results of several studies indicate that the addition of the intracameral lidocaine during cataract surgery is a useful support for topical anesthesia.4-7In most cases, patients do not feel pain during phacoemulsification surgery; however, there is often discomfort during the procedure mainly because of the pressure produced by the liquid flow inside the eye.Conclusion : Preliminary results demonstrate efficacy and safety of the VisThesia concept as a viscoanesthetic method for cataract surgery. It provides a longer anesthetic effect when compared with the application of only an aqueous topical anesthetic.
Posted by mehdi khanlari at 10:33 PM
The Preferred Technique of Dr. Howard Gimbel
Techniques in Ophthalmology 1(1):5–11, 2003
HOWARD V. GIMBEL, M.D., M.P.H.
The history and current techniques of cataract surgery for Howard V. Gimbel are presented. Specifically, the techniques of Trench Divide and Conquer Nuecleofractis,Downslope sculpting, Polar Expeditions, Crater Divide and Conquer, and Phaco Sweep are discussed.
Posted by mmiraftab at 05:53 PM
Second generation vital stains in retinal surgery
BJO June 2003
the novel vital stains trypan blue (TB) and infracyanine green are investigated clinically. These vital stains are promising in vitreoretinal surgery as alternatives to the by now familiar agent indocyanine green
more recently, some doubts have arisen around ICG, as a critical reassessment has followed the initial enthusiasm. As discussed by the authors of both of these papers, greater clinical experience has begun to reveal possible toxic effects of ICG on the RPE and neural retina. Engelbrecht et al published a clinical series that found central RPE atrophy with poor visual outcomes after some cases of ICG assisted macular hole repair, possibly caused by direct contact of ICG with RPE cells in the area of the hole
double staining with trypan blue and infracyanine green to enhance visualisation during macular pucker surgery. One of two important aspects of this paper is the introduction of infracyanine green as an alternative to indocyanine green for vital staining in posterior segment surgery. Under the theory that retinal toxicity may be a consequence of the hypotonicity of standard indocyanine green in its aqueous solvent, the authors have turned to infracyanine green as an iso-osmotic alternative.
Posted by mmiraftab at 04:50 PM
Is There an Association Between Cataract Surgery and Age-related Macular Degeneration? Data From Three Population-based Studies
Am J Ophthalmol 2003;135:849–856.
A history of cataract surgery may be associated with an increased prevalence of late AMD. However, having a severe cataract in the eye may also be associated with a higher prevalence of late AMD. Additional research is needed to investigate whether a causal relationship exists between cataract surgery and AMD or whether this relationship is due to residual confounding or bias.
Posted by mmiraftab at 01:53 PM
May 30, 2003
Corneal Innervation and Morphology in Primary Sjögren’s Syndrome
Investigative ophthalmology and visual science, June, 2003
Ten eyes of 10 patients with primarySjögren’s syndrome ( SS) and 10 eyes of 10 sex- and age-matched control subjects were investigated. In vivo confocal microscopy with through-focusing was used to investigate corneal morphology and to measure corneal sublayer thickness.
In SS, the corneal surface epithelium was irregular and patchy. Anterior keratocytes frequently showed morphologic features of activation. The subbasal nerve fiber bundles revealed abnormal morphology, and the central corneal thickness was reduced by stromal thinning. The findings confirm epithelial, stromal, and neural abnormalities in the corneas of patients with SS.
Posted by afarahi at 09:39 PM
Assessment of colour vision as a screening test for sight threatening diabetic retinopathy before loss of vision
British Journal of Ophthalmology 2003;87:747-752
Aim: To assess the effects of sight threatening diabetic retinopathy (STDR) on colour vision and to evaluate automated tritan contrast threshold (TCT) testing for STDR screening before significant visual loss.
Results: Patients with STDR had significantly worse TCT despite normal BCVA (p<0.0001). TCT yielded a sensitivity of 100% for detecting diabetic maculopathy and 94% for STDR with a specificity of 95%. Logistic regression analyses showed that TCT (p<0.001) and HbA1c (p<0.05) correlated significantly with the presence of STDR but duration of diabetes, urine albumin counts, and BCVA failed to show any significant correlation. No associations between TCT and duration of disease, TCT and HbA1c, and TCT and urine albumin counts were found.
Conclusion: Tritan colour vision deficiency was observed in patients with STDR despite their normal BCVA. These results indicate that automated TCT assessment is an effective and clinically viable technique for detecting STDR, particularly diabetic maculopathy, before visual loss.
Posted by mriazi at 01:01 PM
Extent of foveal tritanopia in diabetes mellitus
British Journal of Ophthalmology 2003;87:742-746
Method: A Wright tristimulus colorimeter was adapted for small field colour matching and colour matches were performed on bipartite fields in the range 12’ to 60’ of arc. The reference stimulus was 490 nm desaturated with 650 nm and the matching stimulus consisted of either two wavelengths (530 nm and 650 nm) or three (460 nm, 530 nm, and 650 nm). The size of the zone of foveal tritanopia was measured using two alternative forced choice presentations of dichromatic and trichromatic matches made by the observer for different field sizes. 21 diabetic and 12 controls performed the experiment.
Results: The results for the controls show a normal distribution, with a median foveal tritanopic zone of 18’ of arc. The median for the diabetic patients was also 18’ of arc, but the distribution showed a significant skew to the right. A non-parametric test shows a significant difference in comparison with the controls (p = 0.01), with several subjects having extensive zones of foveal tritanopia, reaching up to 1 degree.
Conclusions: In the majority of diabetic subjects the extent of foveal tritanopia is normal; however, there is good evidence that in a small number of subjects the size of the zone is significantly increased. This indicates S-cone pathway damage that is sufficiently severe to lead to dichromatic colour vision in the fovea.
Posted by mriazi at 12:51 PM
The effects of dorzolamide on choroidal and retinal perfusion in non-exudative age related macular degeneration
British Journal of Ophthalmology 2003;87:753-757
Results: Compared to placebo, AMD patients treated with dorzolamide showed a significantly increased rapidity of choroidal filling in the superior and inferior peripapillary regions (p=0.007, p=0.02, respectively). No significant difference in choroidal filling times was found in any of the perifoveal areas (p=0.9). Also, on FA assessment, treatment with dorzolamide showed no statistical differences in AVP times (p=0.19).
Conclusions: Dorzolamide may increase peripapillary choroidal perfusion in non-exudative AMD patients. Further studies are merited
Posted by mriazi at 12:44 PM
A clinical follow up of PRK and LASIK in eyes with preoperative abnormal corneal topographies
British Journal of Ophthalmology 2003;87:682-685
A non-randomised comparative study was carried out on 84 eyes that presented with topographic abnormalities before undergoing PRK (n = 44) or LASIK (n = 40) procedures. 84 spherical equivalent paired normal eyes served as the control group. Either PRK or LASIK procedures were performed on 168 eyes using the Summit apex plus excimer laser. Topographic abnormalities, including apex displacement (AD), increased asphericity (AS), meridional irregularity (MI), increased inferior-superior asymmetry (IS), increased curvature (CU), and combined features (CO), were assessed preoperatively using the EyeSys analysis system. Safety and predictability of the two procedures were defined as a postoperative visual acuity of 20/40 or better and the loss of one or more lines of spectacle corrected visual acuity (SCVA). All patients were followed for 6 months. There was a significant loss of best corrected visual acuity in the PRK-AD (p<0.001), PRK-CO (p<0.05), and LASIK-AS (p<0.001) patients. The number of eyes within plus or minus 1.0D of the surgical plan postoperatively was similar in all groups. These data suggest that although predictability was similar, PRK and LASIK performed in corneas with topographic abnormalities might cause loss of vision.
Posted by mmiraftab at 12:40 PM
May 29, 2003
Impact of smoking on the response to treatment of thyroid associated ophthalmopathy
B.J.O, June, 2003
In patients with Graves’ disease, smoking considerably increases the incidence and severity of thyroid associated ophthalmopathy (TAO). The authors sought to determine if smoking also influences the course of TAO during treatment, and the efficacy of therapy.
41 smokers and 19 non-smokers with moderate untreated TAO were included in this prospective study. All patients were treated with steroids and, 6 weeks after the beginning of drug therapy, with orbital irradiation. Proptosis, clinical activity score (CAS), and motility were evaluated. The extent of smoking was derived from the concentration of the haemoglobin adduct N-2-hydroxyethylvaline (HEV), a parameter of long term smoking.
There was no difference in the clinical manifestations of TAO between smokers and non-smokers at the beginning of treatment. However, CAS decreased (p<0.05) and motility improved (p<0.02) significantly faster and to a greater extent in non-smokers than smokers. Inverse correlations between the CAS decrease and the HEV levels observed 4.5 and 7.5 months after the beginning of treatment and between the improvement of motility and the HEV levels after 1.5, 4.5, and 7.5 months indicated a dose dependence. Conclusion: Smoking influences the course of TAO during treatment in a dose dependent manner. The response to treatment is delayed and considerably poorer in smokers.
Posted by afarahi at 05:44 PM
May 27, 2003
Efficacy of Ketotifen Fumarate 0.025% Ophthalmic Solution Compared With Placebo in the Conjunctival Allergen Challenge Model
Arch Ophthalmol. 2003; may,121:626-630.
Background: Ketotifen fumarate blocks histamine1 (H1) receptors, stabilizes mast cells, and acts as an eosinophil inhibitor (decreases chemotaxis and activation of eosinophils). Objective To assess the efficacy of ketotifen 0.025% ophthalmic solution in the prevention of symptoms of allergic conjunctivitis, using the conjunctival allergen challenge model.
Conclusions: Ketotifen was safe and statistically effective in reducing ocular itching and hyperemia associated with allergic conjunctivitis. Ketotifen's rapid onset of action (within 15 minutes) and extended duration of action (at least 8 hours) make it a valuable treatment for allergic conjunctivitis.
Posted by pakravanmd at 09:29 PM
Intraoperative Arcuate Transverse Keratotomy With Phacoemulsification
JOURNAL OF REFRACTIVE SURGERY Nov/Dec 2002
To evaluate the efficacy of paired intraoperative arcuate transverse keratotomy at a 7-mm-diameter zone along with a 3.5-mm clear corneal phaco tunnel in the steeper axis to correct pre-existing astigmatism.A prospective randomized case-control study was conducted on 34 eyes of 28 patients with immature senile cataract. They were divided into two groups; in one group (17 eyes) intraoperative arcuate keratotomy was coupled with phacoemulsification in the steeper meridian (arcuate keratotomy group; mean preoperative astigmatism 2.28 ± 0.89 D) and the other group (17 eyes) phacoemulsification was performed in the steeper meridian without arcuate keratotomy (control group; mean preoperative astigmatism 2.04 ± 0.50 D). The patients were examined at 1 day, and 1, 4, and 8 weeks postoperatively. Correction of keratometric astigmatism, surgically induced refractive changes, magnitude and axis of cylinder, spherical equivalent refraction, with and against the wound change, and coupling ratio were evaluated.Mean reduction in keratometric astigmatism in the keratotomy group was 1.26 ± 0.54 D (P = .0067) and in the control group was 0.48 ± 0.60 D (P = .0423). The difference in reduction of keratometric astigmatism between the two groups was statistically significant (P = .0296). Surgically induced refractive change at 8 weeks follow-up was 2.15 ± 1.13 D in the keratotomy group and 1.50 ± 1.32 D in the control group (P = .046). Coupling ratio was -1.10 ± 0.43 in the keratotomy group at 8 weeks after surgery while the control group was -0.82 ± 0.38.A combination of intraoperative arcuate keratotomy with steep axis phacoemulsification incision is more effective than steep axis phacoemulsification incision alone in reducing pre-existing astigmatism. [J Refract Surg 2002;18: 725-730]
Posted by alireza habibollahi at 04:01 PM
Diversity of animal eyes
About 5 MB PDF file
Posted by mmiraftab at 12:22 AM
May 26, 2003
What is the Risk of Developing Pigmentary Glaucoma from Pigment Dispersion Syndrome?
AJO June 2003
The risk of developing pigmentary glaucoma from pigment dispersion syndrome was 10% at 5 years, and 15% at 15 years. Intraocular pressure greater than 21 mm Hg at the initial examination was associated with an increased risk of conversion
Posted by mmiraftab at 11:48 PM
Lutein and Zeaxanthin Status and Risk of Age-Related Macular Degeneration
Investigative Ophthalmology and Visual Science. 2003;44:2461-2465.
Risk of age-related macular degeneration (early or late) was significantly higher in people with lower plasma concentrations of zeaxanthin. Compared with those whose plasma concentrations of zeaxanthin were in the highest third of the distribution, people whose plasma concentration was in the lowest third had an odds ratio for risk of age-related macular degeneration of 2.0 (95% confidence interval [CI] 1.0–4.1), after adjustment for age and other risk factors. Risk of age-related macular degeneration was increased in people with the lowest plasma concentrations of lutein plus zeaxanthin (odds ratio [OR] 1.9, 95% CI 0.9–3.5) and in those with the lowest concentrations of lutein (OR 1.7, 95% CI 0.9–3.3), but neither of these relations was statistically significant.These findings provide support for the view that zeaxanthin may protect against age-related macular degeneration.
Posted by mmiraftab at 11:09 PM
Catheter-based anaesthesia
Eurotimes May 2003
DELIVERING local anaesthesia with a flexible, indwelling catheter during retinal surgery procedures may offer advantages over the traditional single needle retrobulbar approach, a new study suggests.The technique is similar to the epidural catheters A team of Canadian and German researchers evaluated the novel anaesthetic technique in a series of 100 pars plana vitrectomies in 88 patients. The procedures ranged from 20 to 220 minutes. All patients received initial retrobulbar injections of 7.0ml mepivacaine 2%, after which a 28-gauge flexible catheter was introduced into the retrobulbar space.During surgery, patients were asked to rank their pain on a scale of one (no pain) to 10 (intense pain). The team provided 2.0ml of a local anaesthetic via the catheter whenever the pain level exceeded three on the scale. The catheter can be left in for two or three days after surgery. This means that local anaesthesia can be delivered for postoperative pain relief using smaller amounts of drug than provided by other routes. However, patients should not be sent home with the indwelling catheters.
Posted by mehdi khanlari at 11:08 PM
Analysis of PCO: EPCO 2000
Eurotimes May 2003
“Accurate PCO analysis is important for measuring the effect of treatments that aim to reduce PCO such as intraoperative pharmaceutical treatments or varying types of surgery. It is also an important tool for comparing rates of PCO between many available lenses and the rates of progression with lenses over time. The optimal system should quantify PCO objectively, with results that correlate well with changes in vision. The ideal system should be sensitive enough to pick up small difference in PCO progression, yet specific enough to compensate for artefacts such as lens edge.Visual acuity testing and keeping track of the incidence of YAG surgery required after cataract surgery are two methods that provide some idea of postoperative PCO development. However, visual acuity can be affected by many factors other than PCO. The YAG-surgery metric is useful, but is subject to many secondary factors such as economics and practice patterns of specific surgeons. Subjective slit lamp grading of PCO, typically on a 0-3 scale, is still widely used. However, that approach is not quantitative and is subject to observer bias. It also does not lend itself well to following progression of PCO over time, the researchers note.The Scheimpflug system is a far more high-tech approach. The system utilises the EAS-1000 anterior eye segment analysis system (Nidek), equipped to perform densitometry and light scattering intensity. That system has been shown to be efficient and reliable. However, this approach requires equipment that is not readily available in many ophthalmology departments.The EPCO 2000 digital photo acquisition system, in contrast, only requires equipment that is typically available in any ophthalmology department. The images can be acquired at a slit lamp equipped with a digital camera, or scanned from film if necessary. The system offers rapid access to the images with minimal observer biasIt has shown itself capable of detecting and following early PCO progression More information is available online at www.epco2000.de.
Posted by mehdi khanlari at 10:58 PM
May 25, 2003
Anterior Lamellar Keratoplasty With a Microkeratome: A Method for Managing Complications After Refractive Surgery
JOURNAL OF REFRACTIVE SURGERY January/February 2003
To demonstrate a technique of anterior lamellar keratoplasty with standardized and automated preparation of surface-parallel cuts in both donor and recipient appropriate for addressing several problems after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).We report a noncomparative series of ten eyes with complications after LASIK and PRK. Lamellar cuts were performed in donor and recipient eyes by means of an automated microkeratome. Lamellar grafts were fixed by only four single sutures. In two eyes, a re-lift LASIK was performed after 6 months.Surgery was uneventful and visual acuity was improved in all eyes. Residual irregular astigmatism and refractive error were corrected in two eyes by means of excimer laser computer-assisted ablation and resulted in a further improvement of uncorrected and best spectacle-corrected visual acuity.
EMKH.
Posted by alireza habibollahi at 11:46 PM
A new method for tear film stability analysis using videokeratography
AJO May 2003
To report a new tear film stability analysis system using videokeratography.New videokeratography software for TMS-2N (topographic modeling system; TOMEY Corporation, Nagoya, Japan) was developed that can automatically capture consecutive corneal surface images every second for 10 seconds. Forty-eight adult volunteers (80 eyes) were recruited for this study, and all subjects were examined with the new system. Corneal topographs were analyzed for tear breakup time (TMS-BUT) and the ratio of breakup area to entire color-code area (TMS-BUA) was calculated. Routine methods for tear film breakup time evaluation using slit-lamp microscope and fluorescence staining (SLE-BUT) were performed for comparison purposes. Regressive correlations of TMS-BUT or TMS-BUA with SLE-BUT were analyzed. Based on SLE results, subjects were separated into two groups with normal and short BUT, respectively. TMS-BUT and TMS-BUA were compared with SLE-BUT data with regard to the sensitivity and specificity of evaluation of dry eye symptoms.Topographic modeling system–tear breakup time (TMS–BUT) had a positive correlation with SLE-BUT (R = 0.7219, P < .0001), whereas TMS-BUA showed a negative correlation (R = 0.6317, P < .0001).Topographic modeling system–BUT and TMS-BUA displayed a similar rate of specificity in comparison with SLE-BUT.
Conclusions : This new videokeratography system is a noninvasive and objective method with increased sensitivity for tear film stability analysis
Posted by mehdi khanlari at 11:09 PM
Visual perception during phacoemulsification cataract surgery under topical and regional anaesthesia
Acta Ophthalmologica Scandinavica Volume April 2003
To compare the subjective visual experiences of patients during phacoemulsification and intraocular lens (IOL) implantation using regional and topical anaesthesia. Three different methods of local anaesthesia were used: 66 (26.7%) of the patients were given topical anaesthesia (TA); 74 (30.0%) were given sub-Tenon's anaesthesia (SA), and 107(43.3%) were given peribulbar anaesthesia (PA). The patients were interviewed immediately after surgery by theatre staff using a standardized questionnaire that investigated their intraoperative visual experiences.There was no significant difference between the three methods of anaesthesia regarding light perception during the surgery. However, patients undergoing surgery under TA experienced brighter light intensity levels (78.3%) than those given SA (50.0%) and PA (55.7%) (p = 0.02). A total of 69.6% of subjects who received TA reported visual perception of colours during surgery, as opposed to 56.8% of SA recipients and 49.0% of PA recipients (p = 0.02). In addition, patients under TA were more aware of surgical instruments (26.1%) than those under SA (10.8%) and PA (15.9%) (p = 0.08). The vast majority of patients in all three groups found the visual experience to be non-frightening. There were no associations between intraoperative visual impression and age or sex. Although not statistically significant (p = 0.06), prior cataract surgery appeared to alleviate some of the anxiety associated with the visual experience.
Conclusion: Patients undergoing regional and topical anaesthesia experience a wide variety of visual sensations during surgery. The differences in visual impressions between the groups may reflect the varying degrees of optic nerve blockade that result from the different anaesthetics
Posted by mehdi khanlari at 10:39 PM
Excimer laser "corneal shaping": a new technique for customized trephination in penetrating keratoplasty Graefe's Archive for Clinical and Experimental Ophthalmology May 2003
Trephination of donor buttons and recipient beds was achieved in six animals by conventional mechanical trephination and in six by excimer laser trephination with a guided laser beam in a non-circular geometry. The surgical procedure of full-thickness excimer laser trephination could be performed reproducibly in the animal model both for dissection of the donor buttons and for preparation of the recipient beds. Keratoplasty was performed with kidney-shaped transplants after trephination in free form with the guided laser beam. Postoperative clinical follow-up did not show any differences between the two trephination groups that could be related to the applied trephination technique. After 6 months we observed well-adapted and clear corneal grafts, kidney-shaped in the excimer trephination group and circular in the mechanical trephination group. No side effects on the crystalline lens and the central retina could be clinically observed following excimer laser trephination.
Conclusion We present the first experimental study of keratoplasty with freely selected transplant geometry and perfect congruence of donor button and recipient bed. The application of this technique in certain corneal disorders in humans will offer improved treatment options in the future.
Posted by mehdi khanlari at 09:01 PM
Factors Predicting Upshoots and Downshoots in Duane’s Retraction Syndrome Journal Of Pediatric Ophthalmology and Strabismus , May/June , 2003
This retrospective study evaluated upshoots and downshoots in 196 patients (222 eyes) with Duane’s retraction syndrome seen between January 1990 and July 2001. Upshoots and downshoots were present in 39% of the eyes. The mechanical type was more common than the innervational type (26% vs 12%). Both types of upshoots and downshoots were significantly more common in type lll Duane’s retraction syndrome. A statistically significant association was found between exotropia and the mechanical type, and between vertical tropia in primary position and the innervational type.
Posted by afarahi at 12:25 AM
May 24, 2003
Basics of cryoanalgesia
Eurotimes May 2003
WHEN performing cryoanalgesia, Dr Gutiérrez-Carmona cools all the surgical fluids, except povidone, to approximately 40C. He also cools the eye first by applying a gel-containing mask for 10 minutes to reduce lid sensitivity and facilitate insertion of the lid speculum. Cold methylcellululose is instilled in the eye after placement of 5% povidone drops to reduce the stinging sensation caused by the antiseptic agent.Next, the eye is irrigated with cool BSS prior to create the paracentesis. A cool, high-density viscoelastic is injected into the anterior chamber and a clear cornea incision is made using a 3.2mm phaco knife, while the ocular surface is cooled with BSS and the eye stabilised using a lens manipulator or spatula.This surgery must be performed only through a clear corneal incision and touching the conjunctiva or sclera, as well as using forceps to stabilise the eye, must be avoided. Dr Gutiérrez-Carmona uses either a Barraquer speculum or Castroviejo speculum for blepharostaxis.
The capsulorhexis is performed with a capsular forceps and the nucleus hydrodissected using cold BSS. Phaco of the nucleus is performed using a cooled irrigating solution. If higher phaco energy is being used when operating on a hard nucleus, some patients may complain of pain. In that situation, it may be necessary to decrease the ultrasound power.The cornea is also cooled before enlarging the incision for implantation of a foldable IOL. Some patients will develop increased blinking in response to the ongoing application of the cool BSS onto the eye. That reaction is not very common and usually does not interfere with the surgery. If necessary, the frequency of the instillation can be decreased and a Castroviejo speculum inserted, or BSS can be substituted with cold methylcellulose. If the surgery is prolonged and the temperature of the BSS or irrigating solution is rising, the flasks should be changed.
Posted by mehdi khanlari at 10:44 PM
Local anesthesia efficient for some strabismus surgery
OSN May 24, 2003
Local anesthesia can be more efficient than general for some strabismus surgeries, according to surgeons here. Intravenous propofol sedation and local anesthesia can lead to shorter recovery times and quicker hospital discharges than general anesthesia in adult patients undergoing strabismus surgery,
Posted by mmiraftab at 09:26 PM
May 23, 2003
[5/23/2003 4:47 PM / Sedigheh chinichian , MD ]
Subtenon Injection of Botulinum Toxin for Treatment of Traumatic Sixth Nerve Palsy
Journal Of Pediatric Ophthalmology and Strabismus Vol. 40 No. 1 January/February 2003
This study was designed to evaluate the clinical efficacy of subtenon injection and to compare our results with those in previously published reports.During 3 years , 13 patients with traumatic sixth nerve palsy of less than 6 months’ duration were treated with subtenon injection of botulinum toxin. The average pre-injection deviation was 39.5 PD of esotropia, and the post-injection deviation was 17.0 PD. Seven patients experienced recovery and regained binocular single vision; the overall recovery rate was 53.8% (unilateral, 63.6%; bilateral, 0%). Six patients did not recover and subsequently underwent strabismus surgery. Patients showed higher recovery rates than did most patients treated with conservative measures in published reports. The result without electromyography (EMG) guidance was comparable to that obtained using EMG-guided intramuscular injection of botulinum toxin.
ESMM
Posted by sedigheh chinichian at 04:56 PM
Ibopamine resolve ocular hypotony
European Journal of Ophthalmology 2003; 13: 370 - 376
Ibopamine (3,4 di-isobutyryl ester of N-methyldopamine) is an alpha-adrenergic and dopaminergic drug that,after ocular instillation, has non-cycloplegic mydriatic activity and increases aqueous humor production both in normal and glaucomatous eyes. The increase in aqueous humor production by the ciliary body seems to be related to stimulation of D1dopamine receptors (4). It is seen only in glaucomatous eyes, with an increase in intraocular pressure(IOP), which is independent of the mydriatic effect,
Systemic exposure to ibopamine eye drops is clinically negligible; after instillation, plasma levels were lower than the limit of detection (6). Topical ibopamine does not induce systemic side effects and is very well tolerated by the eye even after repeated instillations.The specific pharmacodynamic characteristics of ibopamine, particularly its effect on aqueous humor production, suggest its use in the early diagnosis of ocular hydrodynamic disorders and to resolve ocular hypotony, which is often a real concern in clinical practice
Posted by mmiraftab at 03:24 AM
May 21, 2003
CIBA Vision to Distribute Centurion SES Microkeratome
CRSTODAY May 2003
CIBA Vision Corporation (Atlanta, GA) has signed a distribution agreement with BioVision AG (Switzerland) to distribute BioVision’s blade-cartridge microkeratome. CIBA Vision will market the FDA-approved device under the name Centurion SES. The device’s proprietary cutting system integrates the blade and the cartridge into one component and achieves applanation using a bar applanator, rather than a plate applanator. According to CIBA Vision, the Centurion SES applanates only the section of the cornea directly in front of the blade, providing a feathered cut with smoother-edged corneal flaps.
“This device is a tremendous win-win for doctors and patients alike,” said Robin Terrell, President of CIBA Vision Surgical. “Its unique microkeratome design gives ophthalmologists the ability to create gutterless LASIK flaps, which could promote faster, more complete healing of the epithelial flap margin. And soon it will give surgeons the ability to perform surface ablation procedures with mechanically separated epithelial flaps. The Centurion SES separator is planned for introduction later this .
Posted by mtmdop at 07:39 AM
May 20, 2003
Topical anaesthesia: a risk factor for post-cataract-extraction endophthalmitis?
Clinical & Experimental Ophthalmology, April, 2003
A retrospective study was conducted of one surgeon's cataract surgery between October 1997 and October 2001.Between October 1997 and May 2000, there were 633 cataract extractions performed with 219 patients operated under topical anaesthesia and 414 under retrobulbar injection. The selection criteria were that surgically easier cases underwent topical anaesthesia. There were five patients who suffered postoperative endophthalmitis in their first week, of which four cases were under topical anaesthesia. There was a complicated case, operated under retrobulbar anaesthesia, who had a low-grade endophthalmitis in the second postoperative week. The four topical cases and the case from the second week all grew Staphylococcus epidermidis. The retrobulbar case developing endophthalmitis in the first week grew alpha haemolytic Streptococcus. After May 2000, there was a change to performing all cataract surgery under retrobulbar anaesthesia and the next 453 cases had no incidence of endophthalmitis.
Conclusion: Topical anaesthesia techniques in temporal clear corneal cataract extraction may be a factor in endophthalmitis.
Posted by afarahi at 11:48 AM
Blepharophimosis: a recommendation for early surgery in patients with severe ptosis
Clinical and Experimental Ophthalmology, April, 2003
The study is a retrospective case series of 28 patients with blepharophimosis, ptosis and epicanthus inversus syndrome.
Amblyopia was present in 39% of patients. Patients with coexistent strabismus had a 64% incidence of amblyopia compared to 24% for those without strabismus. Hypermetropia was present in 43% of patients and 7% were myopic. Significant astigmatism was found in 40% of patients, but these factors did not increase the risk of amblyopia. Patients with severe ptosis had lower rates of amblyopia than those with moderate ptosis but had their ptosis corrected at a median age of 2 years compared to 5 years for those with moderate ptosis
Conclusions: Patients with blepharophimosis have a high rate of amblyopia. Co-existent strabismus doubles the risk of amblyopia. Ptosis alone causes mild to moderate amblyopia only. Patients with severe ptosis should have their ptosis corrected before 3 years of age, and all other patients should undergo surgery before 5 years of age.
Posted by afarahi at 11:36 AM
Modified bitoric ablation technique offers better safety, VA
OSN, May, 2003
A modified bitoric ablation technique offers improved safety and visual outcomes for the treatment of mixed astigmatism, according to a presentation here. Rodrigo Donoso, MD, discussed results with his modification of the bitoric ablation technique developed by Arturo Chayet, MD“.The technique corrects myopic astigmatism and compound astigmatism by combining a positive cylinder correction in one refractive axis with a negative correction in a different axis.
According to Dr. Donoso, both the standard Chayet technique and his modified version reduce the overall amount of tissue ablated during surgery. He adds 50% to the positive cylinder, which reduces even further the depth of the ablation and provides a larger optical zone,and this modified technique results in a better ablation profile and better quality of vision for the patient by diminishing the hyperopic coupling.
Dr. Donoso evaluated the technique in the treatment of cylinder with LASIK in mixed astigmatism. “The best strategy is to use a greater magnitude of positive cylinder to reduce the tissue ablation,the modified Chayet technique is better and safer than the classic Chayet technique,the correction and safety results were better than those obtained with the unmodified Chayet technique'.He said he has not needed to perform any re-operations.
Posted by afarahi at 11:16 AM
May 18, 2003
Other Three New Drugs For Dry Eye
Eurotimes May 2003
Diquafosol tetrasodium (IN365, Inspire Pharmaceuticals) was designed to activate P2Y2 receptors in the mucosal cells of the palpebral conjunctiva and thereby stimulate production of a fluid from those cells containing electrolytes, water and mucin. Phase III studies of diquafosol demonstrated significant improvement in corneal staining. It might find a particular role in patients with “burned out dry eye” who have suffered permanent lacrimal gland damage and are therefore unresponsive to anti-inflammatory treatment with cyclosporine and might be a useful adjuvant therapy for patients with moderate-to-severe disease who are being started on cyclosporine.
It takes one to three months for patients to benefit from cyclosporine treatment, but diquafosol appears to have a faster onset of action and so it theoretically might provide interim relief until cyclosporine takes effect.
Systane contains HP-Guar and borate which undergo a cross-linking reaction on contact with the physiological pH of the ocular surface. The result is transformation of the liquid product into a gel-like membrane that spreads over the cornea and conjunctiva and attaches itself to areas of existing epithelial cell damage. The polymerised membrane persists for hours, allowing epithelial repair to occur in a healthy environment. In clinical trials, Systane reduced corneal staining by 51%. Compared with a commercially available artificial tear product, it was better in relieving morning dryness, evening dryness and foreign body sensation.Systane fulfills a previously unmet need for a dry eye product that provides durable ocular surface protection. Ophthalmologists who encourage their patients to try this new product might find it will become their recommendation of choice for an OTC agent to manage dry eye.
Refresh Endura is a preservative-free emulsion with ingredients which treat all three layers of the tear film. In addition to an aqueous component, Refresh Endura contains a demulcent that enhances the mucin layer of the tears along with a lipid component, castor oil.By providing lipid supplementation, Refresh Endura may also have a particular role in treating patients with meibomian gland dysfunction who are affected by tear lipid deficiency
Posted by mehdi khanlari at 10:51 PM
A challenging case of toric Artisan insertion
Eurotimes May 2003
A colleague referred to his centre a young female patient who had an unsatisfactory postoperative outcome after implantation of a toric Verisyse lens. The patient, an ophthalmic nurse, had requested the procedure for the correction of hyperopia and astigmatism. Postoperatively, the patient complained of decreased visual acuity and blurred vision with spectacle correction.The surgeon who implanted the lens thought he missed the target axis. However, when he re-dialled the lens seven degrees the outcome did not improve and the patient was left with a UCVA of 20/60 and a BCVA 20/20.Careful examination had ruled out all of the usual causes of an unsatisfactory outcome. The IOL was well-centred, the patient had a calm anterior segment, and there was no inflammation or macular changes and the patient had no orthoptic pathology.Furthermore, there were no clinically relevant topographical changes compared to preoperative measurements and there was no irregular astigmatism which might have explained blurred vision. However, aberrometry showed that the patient had 1.0 D of hyperopia with 3.0 D of astigmatism and very high coma of 1.3 microns, postoperatively. What ultimately revealed the nature of the problem was an assessment of the eye with the IOLMaster. The IOLMaster not only provides the white-to-white measurements but also determines the line of sight. In this patient the line of sight was decentred nasally and inferiorly, which is not uncommon in hyperopic eyes. "This was a case where we had to displace and individualise this lens and this is an option only the Verisyse offers. So we re-enclavated a little bit nasally and inferiorly bringing the centre of the lens closer to the line of sight and that solved the problem. The patient came out with an uncorrected visual acuity of 20/20 the coma decreased by 400% and she was very happy." Other phakic refractive lenses currently available could not be customised for a patient with a decentred line of sight. Their haptics do not allow adjustable centration without causing harm to intraocular structures or impairing the optical function of the lens. "To my knowledge the Verisyse is the only phakic IOL at the moment that allows individualised solutions."
Posted by mmiraftab at 10:46 AM
Ischemic optic neuropathy as the first manifestation of elevated cholesterol levels in young patients
Ophthalmology May 2003
Thirty-seven cases (51 eyes) and 74 age- and gender-matched control subjects were identified for this case control study.
The mean total cholesterol level was significantly increased in patients with NAION compared with controls (235.4 vs. 204.0 mg/dl, P < 0.001). Diabetes mellitus was more common in cases than controls (P = 0.027), but systemic hypertension was not significantly different (P = 0.63).
Conclusion:Hypercholesterolemia is a risk factor for NAION in patients aged 50 years or younger and may be the first manifestation of elevated serum lipids. Cholesterol-associated ischemic optic neuropathy is otherwise indistinguishable from idiopathic NAION and should be suspected in relatively young patients with optic disc edema or optic nerve pallor, especially those who do not have other vasculopathic risk factors and do not have clinical or neuroradiologic evidence of demyelinating optic neuropathy or a compressive lesion. Recognition of this syndrome may lead to earlier detection and treatment of serum lipid abnormalities, especially in young patients.
Posted by afarahi at 12:35 AM
Gene Mutation Exacerbates Eye Defect in Inherited Glaucoma
Science March 2003
While studying mice with a mutant gene whose counterpart causes inherited glaucoma in humans, researchers have discovered a second gene mutation that worsens the structural eye defect that causes this type of glaucoma.The newly discovered gene mutation affects production of L-DOPA. The researchers suggest that it might be feasible to prevent glaucoma by administering L-DOPA, which is used in treating Parkinson's disease.
Posted by mmiraftab at 12:01 AM
May 17, 2003
Japan's Share of Published Research in Ophthalmology
Japanese Journal of Ophthalmology Volume 47, Issue 2 , March-April 2003, Pages 221-224
Ophthalmology journals with higher impact factors were accessed through the Medline database to elicit the number of articles published in 1991–2000 that originated in various countries, including Japan. The proportion of articles with a higher grade of evidence (randomized controlled trials/clinical trials, cohort studies, and case-control studies) was determined for Japan and compared with the average values of the total articles published in these journals. In addition, the percentage of published research from the 20 top-ranking countries was calculated, showing the trend over time.Of the total articles (21,327), Japan's share in the selected ophthalmology journals was 6.5% (1,387 articles), ranking third in the world, following the USA (51.5%) and the UK (11.3%). The recent increase in the share was statistically significant for Japan (P = .01). However, the proportionate value of clinical research evidence was lower for Japan-originated articles than the average value for the total clinical research articles in these journals.Appropriate measures should be taken in the ophthalmology field in Japan to increase the number of clinical research papers with a higher grade of evidence
Posted by mmiraftab at 11:38 PM
Intraocular Pressure in Myopic Patients After Worst-Fechner Anterior Chamber Phakic Intraocular Lens Implantation
JRS March/April 2003
To assess intraocular pressure measured with a Goldmann tonometer over a period of 1 year after implantation of a Worst-Fechner anterior chamber phakic intraocular lens to correct myopia of -7.00 D or more.We performed a prospective, nonmasked study of 100 patients (100 myopic eyes) who had a Worst-Fechner phakic intraocular lens implanted to correct myopia of -7.00 D or greater. Central corneal Goldmann tonometry was performed before surgery and 1, 3, 6, and 12 months after surgery. The influence of different variables was assessed.IOP showed a significant increase of of a mean 2.1 mmHg at 3 months after surgery (P=.001). There was not a statistically significant difference between IOP before surgery and 6 months after PIOL implantation (P=.244) or 1 year after surgery (P=.845). In one eye, the lens was explanted 11 months after surgery because of the presence of ocular hypertension. No variables studied showed a statistically significant difference from before to after surgery.Worst-Fechner anterior chamber phakic intraocular lens implantation led to a slight transitory increase of intraocular pressure during the first 3 months after surgery, but returned to preoperative levels by 6 months after implantation. [J Refract Surg 2003; 19:131-136]
Posted by mehdi khanlari at 10:18 PM
Steps to incorporate wavefront-guided ablation into your practice
OSN May 2003
Educate yourself
Research the technology
Visit clinics and observe the surgery first-hand
Discuss options with your business manager, financial planner, refractive surgery coordinator
Create a plan, timeline to introduce the technology into your practice
Educate your staff
Hold retreats, lunch meetings, to teach your staff members about the technology
Make sure they learn the terminology
Be patient, answer questions and be available to explain complicated issues in simple terms
Educate your patients
Hold patient seminars regularly
Attend all seminars to answer patient questions about refractive surgery options
Be consistent with your data, answer questions, calm fears and allow for as much chair time as needed
Rethink your business model
Decide what you will charge for wavefront-guided ablation
Decide what you will charge for enhancements and “upgrades” for first-time and former patients
Start treating patients
Treat ideal patients who have been on waiting lists for wavefront-guided ablation
Treat one eye at a time
Slowly incorporate the technology into your practice; allow time for learning curve
Posted by mehdi khanlari at 09:40 PM
B&L Will Upgrade Zyoptix Laser
Review of Ophthalmology
Bausch & Lomb is also developing an iris recognition system, according to Christine Oliver, of Bausch & Lomb Surgical. The system is being tested internationally.
“Registration is a huge issue and we’ve been very actively developing a fool-proof registration system over the last couple of years in Germany, which is our technical base,” she says. “And that goes hand in hand with the ability of the tracker that can then compensate for those movements. Because we know that the eye is a dynamic unit and as long as there is a pulse, the eye is subject to move in a number of different ways including the rotational.”
The B&L iris recognition system will be implemented into the diagnostic modules and treatment planner of a future version of the Zyoptix laser system. B&L believes this will increase safety. The system includes multiple cameras, which, Ms. Oliver says, allows for better triangulation on the corneal surface. “It adds robustness to the total system, from the tracking to the diagnostic, and registration portion of [the process]. We’re trying to make sure that the information that is gathered diagnostically, when you take the measurement of the eye and measure the higher order aberrations with the patient in the vertical position is all compensated for when the patient is supine under the laser. We’ve worked on that for a number of years and we are in the testing stage right now.”
By the time the patient has completed the diagnostic segment, the unit will be able to distinguish one eye from the other. “If you happen to put that patient under the laser and you’ve made the mistake of putting the wrong eye with the wrong treatment pattern, the software will automatically tell you you have the wrong eye. There are a lot of loop back systems that will, to the extent possible, eliminate a lot of human error,” says Ms. Oliver
The company has submitted its custom ablation data on Zyoptix for Food and Drug Administration approval. Though the unit that launches in the United State following that approval will not include the rotational upgrade, Ms. Oliver expects that will be added shortly thereafter.
Posted by mmiraftab at 12:20 PM
A new platelet-activating factor that may help prevent diffuse lamellar keratitis following LASIK surgery
Review of Ophthalmology
Researchers at Louisiana State University are testing a new platelet-activating factor that may help prevent diffuse lamellar keratitis following LASIK surgery. In a rabbit model, they administered peribulbar injection of the PAF receptor antagonist LAU 0901. Two animals were injected with cyclodextrin alone and served as controls. LASIK flaps were created in both eyes of all of the animals, and Pseudomonas endotoxin was applied to the corneal mid-stromal bed to trigger a DLK reaction before the flaps were repositioned. The left eyes were treated with one drop of LAU 0901 q.i.d.
Corneas were photographed and immunohistochemical analysis performed. Corneas not treated with LAU 0901 and controls showed severe sterile inflammation in the flap interface and the adjacent stroma. Loss of keratocytes, infiltration with PMNs and monocytes and the presence of epithelial cells were also evident at day one. In the treated eyes, there was minimal loss of keratocytes, minimal inflammatory cell infiltration and minimal presence of epithelial cells from day one through day eight, the end of the study. The investigators postulate that LAU 0901 blocks keratocyte apoptosis, the release of cytokines and the migration of inflammatory cells, while allowing the migration of fibroblasts and myofibroblasts to the wound site
Posted by mmiraftab at 12:14 PM
Orthokeratology:corneal refractive therapy (CRT)
Review of Ophthalmology
A number of this year’s papers in ARVO address the issue of predictability of success with corneal refractive therapy. In St. Louis, researchers compared the effectiveness of overnight orthokeratology in RGP wearers and non-RGP wearers. They studied a total of 30 eyes with myopia ranging from
-0.50 to -4.50 D. The average baseline myopia was -2.33 D in the non-RGP group and -2.71 D in the RGP group. Each subject was fit with BE OK lenses (Precision Optics) using Mount-ford’s sag fitting approach. Patients were advised to wear their lenses every night for eight to 10 hours.
At one month, the average decrease in myopia was -2.64 D in the non-RGP group and -2.34 D in the RGP group. Using regression analysis, the re-search team determined that eccentricity of the cornea is a better predictor for the RGP group, whereas in the non-RGP group, greater predictability was more related to the patient’s baseline myopia; that is, the higher refractive errors had a more predictable change than the lower refractive errors
Posted by mmiraftab at 12:11 PM
Remove opacified IOLs sooner rather than later
OSN May 2003
Opacified IOLs must be replaced as soon as possible, Tadeu Cvintal, MD, advised surgeons here during the Brazilian Congress on Cataract and Refractive Surgery. IOL opacification manifests in numerous ways, Dr. Cvintal said. Often the patient does not notice any change in quality of vision, but he or she might begin complaining of glare and reduced visual acuity a year after implantation. The longer a surgeon waits to remove an opacified IOL, “the harder it gets due to a progressive, abnormal adherence between the lens and the capsule and due to a capsule rupture already present, which is aggravated during surgery,
Posted by mmiraftab at 11:23 AM
Short-term Effect of Dorzolamide Hydrochloride on Central Corneal Thickness in Humans With Cornea Guttata
Arch Ophthalmol.Vol. 121 No. 5, May 2003;121:621-625.
In this randomized, placebo-controlled, double-masked, 3-drug crossover study, 20 patients with cornea guttata (mean endothelial cell count, 1321 cells/mm2) and 8 healthy control subjects (mean endothelial cell count, 2483 cells/mm2) were included. Study medications included 2% dorzolamide hydrochloride (Trusopt 2% eye drops; Merck & Co Inc, Whitehouse Station, NJ), 0.9% saline solution (saline placebo), and a solution identical to the carrier substance of dorzolamide in Trusopt (carrier placebo). The study drugs were applied 4 times per day for 1 day only. Central corneal thickness measurements were performed using partial coherence interferometry on every study day at baseline and after 24 hours of study medication treatment.The mean thickening in central corneal thickness within 24 hours in eyes with cornea guttata treated with dorzolamide, saline placebo, and carrier placebo was 12.0 µm (95% confidence interval [CI], 7.0-17.1 µm), 0.6 µm (95% CI, -1.0 to 2.2 µm), and 1.3 µm (95% CI, -0.1 to 2.6 µm), respectively.Application of dorzolamide for 1 day results in a slight but statistically significant thickening of central corneal thickness in patients with cornea guttata.
Posted by mmiraftab at 10:50 AM
Replacing the Amsler grid,a new method for monitoring patients with age-related macular degeneration
Ophthalmology (2003) 110: 966-970
To investigate a method that uses hyperacuity, the Macular Computerized Psychophysical Test (MCPT), to evaluate the central macular visual field in patients with age-related macular degeneration (AMD),a prospective case-control study done on one hundred eight eyes of 108 Patients with AMD and 51 eyes of 51 age-matched patients with no retinal disease. Patients with AMD included 32 (30%) patients with choroidal neovascularization (CNV), 23 (21%) with geographic atrophy (GA), 35 (32%) with AMD with high-risk characteristics (HRC), and 18 (17%) with early AMD with non-HRC. Each subject underwent the MCPT, in which a virtual line composed of dots (white dots on a black background, maximal contrast) is flashed across different macular loci to a perifoveal radius of 7°. Patients’ responses were recorded and automatically analyzed using a specific algorithm developed before the onset of the study. All patients also underwent a supervised Amsler grid examination on the encounter before or after the MCPT in random order.Distortion, scotoma, or blurring perceived by the patient after a swift change of fixation was considered positive on the MCPT. Any perception of distortion, scotoma, or blurring was considered positive on the Amsler grid. RESULTS: Of the 32 patients with CNV, 30 (94%) were found positive on the MCPT and 11 (34%) were found positive on the Amsler grid. Of the 23 GA patients, 21 (91%) were found positive on the MCPT and 7 (30%) were found positive on the Amsler grid. Of the 35 HRC patients, 28 (80%) were found positive on the MCPT and 3 (9%) were found positive on the Amsler grid, and of the 18 early AMD with non-HRC patients, 8 (44%) were found positive on the MCPT and 3 (17%) were found positive on the Amsler grid. Of the 51 controls, 3 (6%) were positive on the MCPT and 1 (2%) was positive on the Amsler grid. CONCLUSIONS: The MCPT was superior to the Amsler grid in detecting AMD-related lesions in this cohort. Studies are underway to determine whether the MCPT is feasible for home monitoring to provide early detection of progression to CNV.
Posted by agholami at 12:11 AM
May 16, 2003
ASCRS survey : LASIK continues to be predominant
Ophthalmology Times May 1, 2003
The growth of LASIK performed by ASCRS members was from 1996 to 1999. Then it has plateaued and stayed stable since that time," explained Dr. Duffey, affiliated with Premier Medical Eye Group, Mobile, AL. He compared data collected over the last 6 years of surveys conducted by ASCRS. Today, about 50% of the membership does LASIK. In the last 1 1/2 years, the total volume of LASIK cases has dropped by 50%. In practices performing greater than 25 cases per month, 22% performed LASIK in 2001 and only 15% in 2002. The downturn in the economy seems be a major factor. Besides LASIK, clear lens extraction (CLE), phakic IOLs, and PRK all seem to have a bright future, Almost 70% of the ASCRS membership plans to do LASIK in the future, 74% plan on CLE, 65% plan to use phakic IOLs, and 58% PRK. CLE is an option for the 45-year-old and beyond patient with hyperopia and was reflected in the survey data, Dr. Duffey said. "Most refractive surgeons have learned that the upper limit for hyperopic LASIK or hyperopic PRK is really between +3 and +4 D.Phakic IOLs are also an option when they become approved. In the 30-year-old myopic patient with a refractive error of -12 D, 15% of the surgeons would use a phakic IOL and 52% would wait. "But once phakic IOLs are approved, a lot of the surgeons in the wait category will move over to the phakic IOL category.PRK will continue to have a niche even among LASIK surgeons when it is appropriate to do PRK instead of LASIK .RK, ICR, and LTK procedures are on the way out. "Less than 20% of the membership are presently performing these procedures or plan to in the future.LASEK, CK, and scleral expansion bands fall somewhere in between. Forty-five percent of the ASCRS members plan on performing LASEK in the future, 39% CK, and 22% scleral expansion bands. Ten percent of ASCRS members has had LASIK surgery performed on themselves when surveyed in 2002. It has doubled since 1999. In the first 2 years of this survey (1996 and 1997), LASIK went from 0% to 5%. Bilateral LASIK surgery is the standard of care in the United States with 95% of surgeons willing to undertake this approach, Almost 80% of the ASCRS members surveyed said that they owned a corneal topography unit. Zeiss-Humphrey's unit has really taken off with 37% marketshare. EyeSys has fallen behind with 21% of the units, and Tomey is at 16%. VISX still dominates the domestic excimer laser market with 72% of the surgeons performing surgery with its laser. Alcon is a far second contender at 17%, followed by Nidek at 5%, Bausch & Lomb at 4%, and LaserSight at 1%. The Hansatome microkeratome is the top unit used by 58% of the LASIK surgeons followed by four different Moria units. "It is interesting that the femtosecond laser (Pulsion FS, IntraLase) is still only at 1%. It hasn't caught on yet,. Interestingly, 61% of the membership do not anticipate adding a surcharge for custom wavefront laser treatment. The survey was sent to 5,000 U.S. members of ASCRS last September. There were 860 responses (17%), which, although down from past years, is statistically significant, Dr. Duffey said.
Posted by mehdi khanlari at 03:59 PM
Patients taking digoxin may develop color blindness
Ophthalmology Times ,May 1, 2003
London-Routine testing for color vision deficiency is not a reliable method to detect digoxin toxicity in patients taking the drug for heart failure or other cardiac problems, The results of recent study contradict earlier findings that formal color vision testing can be used to screen for digoxin toxicity What had been shown previously was that the assessment of color vision could be used to differentiate those patients who had toxic levels of the drug versus those who had therapeutic levels Studies have discovered impairment in both the tritan and red-green axes. Further, investigators using the Farnsworth-Munsell (F/M) 100 hue test have found a strong positive correlation between the total error score and serum digoxin level. However, the F/M test is difficult to administer in clinical settings, particularly in a hospital, The test consists of 85 caps that form a perfect hue circle of the visual spectrum. The color chips are divided into four groups and must be arranged in the order of color appearance between two fixed end caps. Tritan errors were common in both groups, although in the control group the defects were typically only slight to moderate, while 20% of the patients in the digoxin group had a severe tritan defect. The presence of tritan defects in both groups was not unexpected, since this deficiency occurs in many older patients as a result of the aging process and changes in the characteristics of the eye and the way it filters light The patients receiving digoxin showed a significant number of red-green errors. This defect was identified in 23.3% of the group by the Ishihara test, and in 33.3% of the patients based on the red-green plates of the AO HRR test. In the latter test, 20% of the patients had a slight red-green defect and 13.3% had a significant defect. No patients in the control group failed the Ishihara or the red-green grading plates of the HRR. Investigators found no correlation between serum digoxin concentration and the number of red-green errors, tritan errors, or total errors and no correlation between the total number of errors and the duration of treatment.
Posted by mehdi khanlari at 03:30 PM
Suction-Assisted One-Piece Self-Retaining Wide-Angle Contact Lens for Vitrectomy
Ophthalmic Research 2003;35:170-172
The wide-angle contact lens is a one-piece lens without the case, making it lightweight. The contact inferior surface is enhanced by four quadrant plate extensions. A metal housing is attached to the side of the plate extension with an opening at the inferior surface. A negative suction device is attached to the housing of the lens. A drop of viscoelastic is placed between the lens and the cornea. Suction created by a syringe device holds the contact lens on the cornea. Conclusion: This specially designed lens is lightweight and eliminates the need for a skilled assistant to stabilize the contact lens. It provides a stable well-centered view of the peripheral fundus during vitreous surgery.
Posted by mehdi khanlari at 03:03 PM
Visual perception during phacoemulsification cataract surgery under topical and regional anaesthesia
Acta Ophthalmologica Scandinavica Volume 81 Issue 2 Page 118 - April 2003
To compare the subjective visual experiences of patients during phacoemulsification and intraocular lens (IOL) implantation using regional and topical anaesthesia.
The study cohort consisted of 247 patients without pre-existing ocular pathology who underwent routine phacoemulsification and IOL implantation. The mean age of the subjects was 75.4 ± 9.4 years and 34.5% of them had a history of cataract surgery. Three different methods of local anaesthesia were used: 66 (26.7%) of the patients were given topical anaesthesia (TA); 74 (30.0%) were given sub-Tenon's anaesthesia (SA), and 107(43.3%) were given peribulbar anaesthesia (PA). The patients were interviewed immediately after surgery by theatre staff using a standardized questionnaire that investigated their intraoperative visual experiences.
There was no significant difference between the three methods of anaesthesia regarding light perception during the surgery. However, patients undergoing surgery under TA experienced brighter light intensity levels (78.3%) than those given SA (50.0%) and PA (55.7%) (p = 0.02). A total of 69.6% of subjects who received TA reported visual perception of colours during surgery, as opposed to 56.8% of SA recipients and 49.0% of PA recipients (p = 0.02). In addition, patients under TA were more aware of surgical instruments (26.1%) than those under SA (10.8%) and PA (15.9%) (p = 0.08). The vast majority of patients in all three groups found the visual experience to be non-frightening. There were no associations between intraoperative visual impression and age or sex. Although not statistically significant (p = 0.06), prior cataract surgery appeared to alleviate some of the anxiety associated with the visual experience.
Conclusion: Patients undergoing regional and topical anaesthesia experience a wide variety of visual sensations during surgery. The differences in visual impressions between the groups may reflect the varying degrees of optic nerve blockade that result from the different anaesthetics
Posted by mehdi khanlari at 02:48 PM
Anti-Vascular Endothelial Growth Factor Therapy for Neovascular Age-related Macular Degeneration
Ophthalmology May 2003
Pharmacologic inhibition of angiogenesis represents a novel approach in the treatment of choroidal neovascularization(CNV) in patients with age-related macular degeneration (AMD). Various components of the neovascular process, including growth factor expression, represent potential targets for modulation by drug therapies.
Vascular endothelial growth factor (VEGF) has been demonstrated in human specimens of CNV and animal models have confirmed that this protein is capable of inducing CNV.2 Therefore, targeted inhibition of VEGF seems to be a reasonable approach for the treatment of CNV.
Posted by mmiraftab at 02:26 PM
May 15, 2003
Get rid of the rough surface :the new Medpor Quad-Motility implant
Ophthalmology Times ,may,2003
Many surgeons feel that the porous orbital implants are more likely to erode through the conjunctiva than their non-porous counterparts. This may be due to the rough surface of the implant rubbing and abrading the conjunctiva against the prosthetic shell. 
Figure Compared with the original design (left), the new Medpor Quad-Motility implant has a smooth anterior surface while retaining the large pore size posteriorly to facilitate fibrovascular ingrowth. The anterior mounds have been dyed to demonstrate the difference in surface texture between the two implants
One way to keep this abrasion from occurring is to eliminate the rough surface. This can be accomplished during the manufacturing process of the newer generation of porous polyethylene motility implants. The new Medpor Quad-Motility implant maintains the large pore size posteriorly to facilitate fibrovascular ingrowth into the implant. The anterior surface, however, is smooth to minimize any abrasive effect on the conjunctiva For hydroxyapatite and other porous polyethylene implants, a wrapping material is sometimes used to act as an additional barrier between the rough surface of the implant and the conjunctiva. Donor sclera, pericardium, fascia, acellular dermis, and other materials have been reported to be effective as wrapping materials for orbital implants. A recent report, however, suggested that wrapping of orbital implants was associated with higher complication rates. These materials also add time to the procedure as well as cost to the total operation.
Posted by mehdi khanlari at 09:39 PM
THE NEED FOR INCREASED RESISTANCE PROTECTION: Gatifloxacin(ZYMAR)
Cataract & Refractive Surgery , May ,2003
Although the third-generation fluoroquinolones have served ophthalmologists very well, as is the case with all antibiotics, microbial resistance to those agents is beginning to increase (quite dramatically in many parts of the country). When an antibiotic begins to enter a resistance curve, the effect is slight at first and then becomes quite steep. We are starting to move into that steeper resistance side with previous-generation fluoroquinolones, at which point the antibiotics can lose much of their efficacy. Even the third-generation fluoroquinolones have shown this specific resistance problem. Gatifloxacin’s 8-methoxy group gives the agent two different mechanisms of action (topoisomerase IV and DNA gyrase) against gram-positive organisms (Figure 1). This “double shot” for killing bacteria significantly improves gatifloxacin’s efficacy compared with third-generation fluoroquinolones. Additionally, the dual mechanism of action provides an uncommonly strong level of action against microbial resistance over time In order to resist this dual mechanism, microbes must develop a double mutation spontaneously, which will be much more difficult to achieve. Therefore, this specific antibiotic may be useful for a much longer period of time than previous-generatio fluoroquinolones.Gatifloxacin is designed to be particularly effective against gram-negative organisms. It features unusual properties to combat the highly feared atypical mycobacteria that has become so problematic for refractive surgeons. In addition to this broader spectrum of coverage, all of the minimal inhibitory concentrations are stronger in gatifloxacin than in previous-generation fluoroquinolones. Finally, gatifloxacin has the same penetration rate as ofloxacin, a characteristic that we have shown will be extremely important.
Posted by mehdi khanlari at 08:20 PM
The Importance of Pachymetry With LASIK
Cataract & Refractive Surgery , May ,2003
BY ARTHUR CUMMINGS, MD, FRCSed
I designed a questionnaire for experienced colleagues and friends performing high-volume LASIK surgery. The following questions were included:
1. When did you start performing LASIK?
2. How many LASIK procedures have you
performed?
3. What microkeratome do you use?
4. What flap thickness do you prefer to aim for?
5. What laser do you prefer to use?
6. Have you had any case(s) of post-LASIK ectasia?
7. If yes, what did you think the most important contributing factor(s) were?
8. What is the minimum pre-op pachymetry that you would require for an ideal -2.00 myopic candidate?
9. Would you do LASIK for a pre-op pachymetry of less than 500 µm?
10. Would you do LASIK for a pre-op pachymetry of less than 480 µm?
11. Would you do LASIK for a pre-op pachymetry of less than 460 µm?
12. What are the steepest pre-op K’s that you would do LASIK on for myopia?
13. What are the steepest pre-op K’s that you would do LASIK on for hypermetropia?
14. What are the flattest pre-op K’s that you would do LASIK on for myopia?
15. What are the flattest pre-op K’s that you would do LASIK on for hypermetropia?
16. Any other comments?
PACHYMETRY
Of the 26 surgeons surveyed, 81% responded that they would perform LASIK on a -2.00 D patient who had a preoperative pachymetry reading of less than 500 µm. Also, 69% of the respondents would perform LASIK on a patient with a preoperative pachymetry reading of less than 480 µm, and 23% would perform the procedure with a preoperative measurement of less than 460 µm. The average preoperative pachymetry measurement required for an ideal -2.00 D myopic patient was 472 µm, although this number varied from 425 to 500 µm (Tables 3 and 4).One important factor to emerge from the study was the indication of “flaps thicker than anticipated.” In my opinion, this is the one area in which proactive safeguards can enormously improve the outcome and safety of the LASIK procedure. Both participants in this study and various colleagues of mine in personal communications reported variations in flap thickness as large as 80 µm while using the same microkeratome. Such reports imply a 160-µm head can produce flaps both 120 µm thick and 200 µm thick. Presently, the only method by which to gauge a flap’s thickness is an intraoperative pachymetry test, and the most important lesson to take away from this survey is the necessity of this testing. Once the surgeon determines the residual corneal thickness, he can decide whether to proceed with the ablation as planned or whether to take action to preserve tissue, perhaps by reducing the size of the optical zone.
BREAKING DOWN THE RESULTS
I divided the survey respondents into two groups: surgeons who had performed more than 10,000 LASIK surgeries and those who had performed fewer than 10,000. Six of the surgeons had performed more than 10,000 procedures each, for a combined total of 101,000 surgeries. The other 20 surgeons had performed a combined total of 72,718 LASIK procedures. Next, I compared the surgical approaches to flap thickness between more and less experienced surgeons. I found no fundamental differences, except the more experienced surgeons tended to aim for thinner flaps (135 µm on average vs 155 µm) and also generally left the RCT at 260 µm, whereas the less experienced surgeons required 250 µm on average. I then compared the surgical habits of those surgeons who had experienced a case of corneal ectasia with that of the surgeons who had never encountered the condition. The only significant difference was the group that had experienced ectasia had performed an average of 7,714 procedures, whereas the group that had avoided ectasia had performed 5,772 surgeries. Therefore, the rate of post-LASIK ectasia may directly correlate with the number of surgeries performed.
IN CONCLUSION
The evaluation of a candidate’s suitability for LASIK rests on many factors, one of which is his preoperative corneal pachymetry. It appears surgeons can perform LASIK quite safely on patients with preoperative pachymetry measurements of less than 500 µm as long as these individuals meet other preoperative criteria. Finally, the results of the survey emphasize the importance of intraoperative pachymetry—it should become routine for all surgeons performing LASIK and LASIK enhancements.
Posted by mehdi khanlari at 08:10 PM
May 14, 2003
Infectious organism found in late capsular block syndrome
A new study indicates that an infectious organism may be at the root of some late capsular block syndrome cases. In the recent investigation, two cases of late capsular block syndrome cultured positive for Propionibacterium acnes (P. acnes), Deepinder K. Dhaliwal, MD.is reported.
Late capsular block syndrome is marked by accumulation of milky fluid in a distended capsular bag, typically occurring years after phacoemulsification. Traditionally, practitioners have attributed this to different causes.
Dhaliwal has seen an additional four similar cases that have also raised concern. However, when two of these were subsequently cultured they turned up negative. Of the cases that were not cultured, one involved a patient with macular degeneration. The patient was unable to note any change in vision because of his poor acuity. The other case was a diabetic patient who opted to instead undergo traditional YAG capsulotomy with daily follow-up instead of culture with vancomycin injection. This patient did well postcapsulotomy and did not develop any sign of inflammation or infection.
If you stick the needle in and you don’t aspirate the fluffy material, but just aspirate the fluid, then you don't have the organism,” Dhaliwal said. Because such a tiny amount of fluid is aspirated, the organism could definitely be missed.
The findings here could be of importance. If indeed organisms are present in the distended capsule, performing a Yag-capsulotomy may liberate the bacteria into the vitreous cavity which may cause significant inflammation or infection. P. acnes typically causes more of an inflammatory or a foreign body reaction and so it's a very indolent infection,” Dhaliwal said. “It’s rarely a severe, acute endophthalmitis — it has more of a chronic, smoldering presentation.”
She warns against performing a capsulotomy, as is traditionally done, without subsequently watching the patient. “I think in these patients there should be careful education about signs and symptoms of inflammation, or endophthalmitis,” Dhaliwal said.
The findings are significant, said Nick Mamalis, MD, .“I think that this is a problem that may be going unrecognized,” Mamalis said. “As we learn more and more about this delayed onset capsular block, we’re going to find that as more people see this problem and are beginning to treat it, if they do start taking cultures they may start to see that some of these are indeed positive for P. acnes.” It’s important to at least consider the possibility that P. acnes is present because many times the treatment plan is to open up the posterior capsule with a YAG laser. “If you have P. acnes growing there then theoretically you can spill this infectious material into the vitreous and this could lead to a more significant infection,” Mamalis said.
Simon P. Holland, MD, recently had a case that he believes may have been P. acnes. The patient noticed a smoky film and upon examination a crystalline white deposit was seen around the inferior end of the lens. This subsequently dropped out. It’s important to follow these patients very closely, Holland said, because the recurrence rate is so high. He also recommends that practitioners keep these patients on steroids to suppress the inflammation.
Posted by smrtaheri at 05:27 PM
May 13, 2003
Reduced patching equally effective for amblyopia
OSN May 2003
Archives of Ophthalmology May 2003
Better compliance and happier children may be the results of a recent study of amblyopia.The study found that patching the unaffected eye of a patient with moderate amblyopia for 2 hours daily is as effective as patching the eye for 6 hours. With the shorter therapy session time, better patient compliance is expected, noted a press release from the National Eye Institute, which sponsored the study. “These results will change the way doctors treat moderate amblyopia and make an immediate difference in treatment compliance and the quality of life for children with this eye disorder,” said Paul Sieving, PhD, MD, director of the National Eye Institute. He said one of the main advantages of the shorter treatment regimen is that children can complete the patching at home, avoiding the social stigma of wearing a patch to school. The Pediatric Eye Disease Investigator Group studied 189 patients; 95 were assigned to wear a patch for 2 hours a day and 94 were assigned to wear a patch for 6 hours a day. Average age was 5 years. Parents were requested to have their children wear the patch continuously and spend at least 1 hour with the patch on doing near work activity. After 4 months of follow-up, 97% of patients in the 2-hour group and 95% in the 6-hour group completed the primary outcome exam. Both groups showed substantial improvement in the eye with amblyopia, averaging 2.4 lines improvement from baseline. Vision in the normal eye decreased by 2 lines or less in 21% of the 2-hour group and in 24% of the 6-hour group. The researchers noted that this is a normal occurrence for patients with amblyopia. The unaffected eye is expected to revert to normal after treatment ceases.
Posted by mmiraftab at 11:37 PM
Glaucoma Treatment UPDATE
Ophthalmology Management May 2003
With new innovations and information constantly emerging, the prospects for safe and effective glaucoma treatment with minimal side-effects have never been brighter. Here, surgeons and researchers share the latest information on three cutting-edge treatment approaches, as well as highlights from data on IOP-lowering medications presented at the recent American Glaucoma Society meeting in San Francisco.
Read More...
Posted by mmiraftab at 10:23 PM
Iris Color and Intraocular Pressure: The Blue Mountains Eye Study
Am J Ophthalmol 2003;135:384-386
This population-based, cross-sectional study was performed to assess the relationship between iris color and intraocular pressure (lOP).3,654 largely Caucasian participants, aged 49 to 97 years, were examined from 1992 to 1994. Information was collected about glaucoma risk factors, and Goldmann applanation lOP measurements were taken. Iris color was assessed by comparing the undilated appearance of each eye with three standard photographs. Participants who had previous cataract or glaucoma surgery and those using glaucoma medications were excluded.Mean lOP measurements increased with increasing grades of iris pigmentation. After simultaneous adjustment for variables associated with lOP, mean measurements were 15.92 mm Hg for blue iris color, 16.04 mm Hg for hazel or green, 16.11 mm Hg for tan-brown, and 16.49 mm Hg for dark brown (P for trend = .001).This study demonstrates a modest but statistically significant association between increasing iris color and lOP.
ESMM
Posted by Ali Amini at 07:47 PM
One-Minute Schirmer Test With Anesthesia
Cornea, May, 2003.
A prospective study was performed using 60 eyes of 30 patients. All patients had symptoms of dry eye syndrome. The reliability of the Schirmer test at 30 seconds and 1, 2, 3, and 4 minutes was compared with that of the standard 5-minute test
100% of patients with severe dry eye (defined as a 5-minute Schirmer test of 5.5 mm or less) had a 1-minute Schirmer test less than or equal to 2 mm. Also, 80% of patients with a moderate dry eye (defined as a 5-minute Schirmer test between 5.5 to 10 mm) had a 1-minute test between 3 to 6 mm.
Results of this study support the hypothesis that shorter durations of the 5-minute Schirmer test correlate highly with those of the 5-minute test. Specifically, the 1-minute test correlates highly with the 5-minute test and will make this test much more practical for ophthalmologists
Posted by afarahi at 12:59 AM
Adult strabismus surgery under propofol sedation with local versus general anesthesia
Journal of AAPOS, April, 2003
Thirty adult patients underwent uncomplicated strabismus procedures performed by one surgeon using propofol sedation and local subtenon’s anesthesia. These were retrospectively matched with adult patients undergoing similar procedures by another surgeon using general inhalational anesthesia. Times from incision closure to leaving the operating room (Out OR time), and to hospital discharge (DC time) are compared.
Propofol/local Out OR times ranged 2 to 8 minutes (mean, 4.8). General anesthesia Out OR times ranged from 3 to 28 minutes (mean, 8.8) (means differ at P<.001). At 60 minutes after completion of surgery, 53% of propofol/local patients had left the hospital, whereas none of general patients had left (P<.001). At 2.5 hours after surgery, 100% of propofol/local patients had left the hospital, but 10% of general patients remained, with two staying more than 5 hours.
Conclusions: Many adult strabismus surgeries may be performed more efficiently with intravenous propofol sedation and local subtenon’s anesthesia than with general anesthesia.
Posted by afarahi at 12:30 AM
Complications in infants undergoing surgery for congenital cataract in the first 12 weeks of life: Is early surgery better?
Journal of AAPOS, April, 2003
To determine if there is an association between the timing of surgical intervention for congenital cataract within the first 12 weeks of life and the prevalence of postoperative complications.A retrospective review of records from 1990 to 2000 of infants who underwent surgery for congenital cataract within the first 12 weeks of life was performed.
Eighty eyes in 55 children were involved with a minimum follow up of 6 months. Bilateral cataracts were present in 25 and monocular cataracts in 30 infants. A limbal approach lensectomy–vitrectomy was performed in all infants. The mean age at the time of surgery was 31.5 ± 23.3 days (median, 26.5; range, 2 to 84). Mean follow up from the time of surgery was 2.85 ±1.9 years (median, 2; range, 0.5 to 8). CART analysis suggests that glaucoma is more prevalent in infants when the surgery was performed between 13.5 and 43 days of life (CART = 0.370); nystagmus when surgery is performed between 48 and 84 days of life (CART = 0.500); strabismus when surgery is performed between 55.5 and 84 days of life (CART = 0.600); and secondary membranes when surgery is performed between 26.5 and 40 days of life (CART = 0.4).
Conclusions: Our data suggest that the first 2 weeks of life comprise the most favorable time for decreasing postoperative complications resulting from surgical intervention for infants presenting with cataracts within the first 12 weeks of life.
Posted by afarahi at 12:15 AM
May 12, 2003
Refractive Challenge
Cataract & Refractive Surgery Today May 2003
A 17-year-old Hispanic male presented with preoperative refractive errors of +15.00 -1.75 X 5 = 20/50 OD and +15.25 -0.50 X 55 = 20/50 OS. He was contact lens intolerant and absolutely refused to wear his essentially aphakic spectacles for both cosmetic and functional reasons. He had an UCVA of 10/200 in each eye and obviously found performing his everyday activities to be extremely difficult. The patient’s slit lamp examination, tonometry, and fundus examination were all normal. His keratometry readings were 48.25/49.00 OD and 48.00/48.50 OS, and his axial length measurements with an immersion technique were 16.19 mm OD and 16.11 mm OS. The patient’s white-to-white corneal diameter was 11 mm in both eyes, and his anterior chamber depth was 3.4 mm OU. I was very concerned about his extremely short axial length, which indicated that his eyes were nanophthalmic.
HOW WOULD YOU PROCEED?
1. Would you discourage the patient from undergoing any corrective eye surgery and instead either fit him with glasses or encourage him to reattempt contact lens wear?
2. Recommend a phakic implant such as the STAAR ICL (STAAR Surgical Company, Monrovia, CA) with the understanding that this lens will not be available for at least 2 years unless the patient can be enrolled in an FDA study?
3. Choose to perform clear lensectomies, possibly with piggyback lenses due to the patient’s degree of hyperopia?
Posted by mehdi khanlari at 05:34 AM
FDA Approves Allergan’s ZYMAR, Alcon’s VIGAMOX
Cataract & Refractive Surgery Today May 2003
Allergan, Inc.’s (Irvine, CA), ZYMAR (gatifloxacin ophthalmic solution 0.3%) recently became the first fourth-generation fluoroquinolone to receive FDA approval. Shortly thereafter, VIGAMOX (moxifloxacin ophthalmic solution 0.5%), Alcon Laboratories’ (Fort Worth, TX) fourth-generation fluoroquinolone, was also approved by the FDA.
According to Allergan, ZYMAR is a highly efficacious fluoroquinolone with complete solubility, effective tissue penetration, and low MIC 90s against a broad spectrum of organisms. It has a unique, dual mechanism of action that provides for effective treatment of infection while slowing the development of bacterial resistance, a combination that the company states provides a safer and more effective treatment regimen with high patient success rates. ZYMAR is indicated for the treatment of bacterial conjunctivitis caused by susceptible strains of bacteria. Alcon has studied VIGAMOX solution in three major clinical trials. Its therapeutic benefits include effective treatment of gram-positives, gram-negatives, and other organisms such as Chlamydia. VIGAMOX has a near-neutral pH, which results in a low incidence of stinging and high solubility at a neutral pH of 7.0. Alcon states that VIGAMOX exceeds all USP preservative efficacy requirements without benzalkonium chloride, and it is therefore referred to as being self-preserved or BAK-free.
Posted by mehdi khanlari at 05:02 AM
May 11, 2003
Examination of mechanisms underlying the frequency-doubling illusion
Journal of Vision
PURPOSE. The frequency-doubling illusion is an apparent doubling of spatial frequency when a sinusoidal grating is modulated rapidly in temporal counterphase. Recently, in the context of clinical testing, it has been proposed that the illusion arises from a spatially nonlinear ganglion cell class (Maddess, Goldberg, Dobinson et al. 1999). The current study reexamines this possibility and investigates other mechanisms which may underlie the illusion. METHODS. Human psychophysical thresholds were measured for a variety of grating phase discrimination and matching tasks. Responses of macaque magnocellular (MC-) retinal ganglion cells were also recorded to counterphase-modulated sinusoidal gratings of various spatial frequencies, and the spatial nonlinearity was assessed. RESULTS. No physiological evidence was found of a separate nonlinear MC-cell class. Also, cells' nonlinearity of spatial summation gives a doubled response in time but not in space; no spatially modulated signal can be expected from the nonlinear response of a ganglion cell. Observers were unable to distinguish the temporal phase of counterphase-modulated gratings above ~15 Hz, but could obtain spatial information provided by the grating zero-crossings. These and other measurements suggest that the illusion occurs because central mechanisms lose temporal phase information. CONCLUSIONS. These results argue against the hypothesis that spatially nonlinear retinal ganglion cells are the physiological substrate of the frequency-doubling illusion. A cortical loss of temporal phase discrimination may be the principle cause of the illusion, whereas spatial phase information (i.e., grating position) is retained.
Posted by mmiraftab at 12:37 AM
May 10, 2003
Subconjunctival mitomycin C as adjunctive therapy before pterygium excision
Ophthalmology May 2003
Thirty-six eyes of 36 patients prospectively received 0.1 ml of 0.15 mg/ml mitomycin C subconjunctivally injected into the head of the pterygium 1 month before bare sclera surgical excision.The pterygia resolved in 34 (94%) of 36 eyes, with a recurrence rate of 6% over a mean follow-up of 24.4 months. No wound-healing complication developed in any patient.
Subconjunctival mitomycin C is an effective treatment before pterygium excision. Subconjunctival injection allows exact titration of mitomycin C delivery to the activated fibroblasts and minimizes epithelial toxicity.
Posted by mmiraftab at 11:47 PM
Replacing the Amsler grid
A new method for monitoring patients with age-related macular degeneration
Ophthalmology May 2003
To investigate a method that uses hyperacuity, the Macular Computerized Psychophysical Test (MCPT), to evaluate the central macular visual field in patients with age-related macular degeneration (AMD).Each subject underwent the MCPT, in which a virtual line composed of dots (white dots on a black background, maximal contrast) is flashed across different macular loci to a perifoveal radius of 7°. Patients' responses were recorded and automatically analyzed using a specific algorithm developed before the onset of the study. All patients also underwent a supervised Amsler grid examination on the encounter before or after the MCPT in random order.Distortion, scotoma, or blurring perceived by the patient after a swift change of fixation was considered positive on the MCPT. Any perception of distortion, scotoma, or blurring was considered positive on the Amsler grid.The MCPT was superior to the Amsler grid in detecting AMD-related lesions in this cohort. Studies are underway to determine whether the MCPT is feasible for home monitoring to provide early detection of progression to CNV.
Posted by mmiraftab at 11:41 PM
B&L to delay FDA application for diabetic edema implant
OSN May 2003
Bausch & Lomb will delay filing for regulatory approval of its Retisert implant by up to 3 years, according to a company announcement. The implant, which is being evaluated for treatment of diabetic macular edema, is designed to provide intraocular sustained release of fluocinolone acetonide for up to 3 years.
Retisert side effects. As a treatment for diabetic macular edema, Bausch & Lomb's drug delivery implant, Retisert, showed significantly higher rates of adverse side effects than standard laser therapy. Twelve-month data from a clinical trial indicate that 24.4% of the patients receiving Retisert developed cataracts and 12.2% of the Retisert patients developed complications involving increased IOP, including some cases of glaucoma. Only 3.5% of patients receiving laser therapy developed cataracts and none had IOP increases.A Bausch & Lomb spokesperson said adverse side effects had been expected because Retisert treatment involves a steroid
Posted by mmiraftab at 02:53 PM
May 09, 2003
Amblyopia in astigmatic preschool children
Vision Research 43 (2003) 1081–1090
Best-corrected acuity was measured for vertical and horizontal gratings and for recognition acuity optotypes (Lea Symbols) in a group of three- to five-year-old children with a high prevalence of astigmatism. Results showed meridional amblyopia (MA) among children with simple/compound myopic or mixed astigmatism, due to reduced acuity for horizontal gratings. Children with simple/compound hyperopic astigmatism showed no MA, but did show reduced acuity for both grating orientations. Reduced best-corrected recognition acuity was shown by both myopic/mixed and hyperopic astigmats. These results suggest that optical correction of astigmatism should be provided prior to age three to five years, to prevent development of amblyopia.
Posted by mmiraftab at 01:10 AM
Gene therapy for choroideremia: in vitro rescue mediated by recombinant adenovirus
Vision Research 43 (2003) 919–926
Choroideremia (CHM) is an X-linked retinal degenerative disease resulting from a lack of functional Rab Escort Protein-1 (REP-1). As a first step in developing gene-based therapies for this disease, we evaluated the feasibility of delivering functional REP-1 to defective lymphocytes and fibroblasts isolated from individuals with CHM. A recombinant adenovirus delivering the full-length human cDNA encoding REP-1 under the control of a cytomegalovirus promoter was generated. Adenovirus-mediated delivery of REP-1 rescued the defective cells as assessed through protein and enzymatic assays. Ultimately, it may be possible to use virusmediated delivery of REP-1 to evaluate disease intervention in vivo.
Posted by mmiraftab at 12:57 AM
View the grand prize winners video about higher order aberrations
Posted by mmiraftab at 12:48 AM
New type of cone cell identified
OSN May2003
Researchers believe they have found a new type of cone photoreceptor in the human retina, which may play a role in regulating circadian rhythms and other nonvisual but light-dependent mechanisms. None of the melanopsin-positive cones contain any of the other known types of opsins, such as SW or MW/LW opsins, The melanopsin was detected by performing anti-melanopsin immunohistochemistry on free-floating sections of retina obtained from human cadaver eyes. Previous studies have shown that melanopsin is expressed in a subpopulation of human retinal ganglion cells that are intrinsically photosensitive. The task remains to “define the presence of melanopsin-positive neurons in human retina in order to determine the involvement of this pigment in human circadian photoreception, Melanopsin expressing ganglion cells are considered to play a role in a broad range of nonvisual irradiance-detection processes due to their intrinsic photosensitivity and projections to structures mediating circadian rhythms, pupillary reflex and seasonal rhythms. A similar role can be hypothesized for melanopsin in the human retina,
Posted by mmiraftab at 12:06 AM
May 07, 2003
ASCRS Ophthalmology Image Library
Eyeworld May 2003 
Having trouble finding just the right ophthalmic image for your slide show? Is there a particular image you want to help illustrate a lecture for your students? ASCRS has the answer in the latest addition to its new, growing member service — ASCRS Ophthalmology Image Library. Log on and select a category and subcategory from which to upload or download. The idea for the library was a response to discussions among ASCRS members who participate in the EyeMail listserv. The library is linked to the ASCRS and ASOA member Web sites. To gain access, members of those organizations must log on. Once on, they can select to upload or download images from one of six major categories: Cataract, cornea, glaucoma, pediatric, refractive, and retina. Within those categories, there are some 30 subcategories from which to choose.
Uploading or downloading images is relatively simple. Those who upload an image must agree to give permission to the Library and ASCRS members who use the image, to use the image for noncommercial scientific, medical, or educational purposes. A photo credit is permanently attached to the image. Similarly, those who download images must agree to use them in the manner previously described. Downloaded images can be printed, mailed electronically, or kept in the member’s “my images” location on the Web site.
Posted by mehdi khanlari at 02:13 AM
Systane:another new dry eye therapy
Eyeworld May 2003
Systane Dry Eye Therapy (HP-Guar) is a novel sterile aqueous tear solution. HP-Guar forms a soft network with a gel-like consistency by the molecule binding to hydrophobic surfaces on the ocular epithelium and also by the molecules binding to each other in the tear film, in effect creating an ocular shield. This cross-linking preferentially adheres to disrupted epithelial cells and enhances tear film stability and integrity. This allows for the formation of a microenvironment that protects the surface of the eye while epithelial repair occurs. The ‘soft’ gel that is formed also increases viscosity of the drop in the eye, which prolongs ocular retention and protection.
Understanding how therapy affects both signs and symptoms is increasingly important as new therapies are introduced with different mechanisms of actions. A therapy may relieve symptoms, however if the signs of dry eye, such as tear film break-up time (TFBUT) or corneal staining, are not addressed and treated then symptoms will return. It is thought that Systane, due to the formation of a matrix with components of the ocular surface and tear film to form a contiguous shield over the surface of the eye, may extend TFBUT by increasing the stability of the tear film
Posted by mehdi khanlari at 02:04 AM
Infectious organism found in late capsular block syndrome
Eyeworld May 2003
A new study indicates that an infectious organism may be at the root of some late capsular block syndrome cases. In the recent investigation, two cases of late capsular block syndrome cultured positive for Propionibacterium acnes (P. acnes), Late capsular block syndrome is marked by accumulation of milky fluid in a distended capsular bag, typically occurring years after phacoemulsification. Traditionally, practitioners have attributed this to different causes. “Some propose that the milky fluid behind the intraocular lens is due to proliferating lens epithelial cells, collagen, and extracellular matrix causing an osmotic gradient with secondary aqueous flow into the capsule, Dhaliwal said. When this has been studied previously, cultures have all been negative
Posted by mehdi khanlari at 01:41 AM
The wavefront and tear film breakup connection
Eyeworld May 2003
Because changes in total and corneal aberrations during tear film breakup in human eyes can affect wavefront measurements, I now recommend that measurements be taken within five seconds after a blink for accuracy. It’s clear that in any attempt to use customized ablation to minimize higher order ocular aberrations, care will need to be taken in selecting the time interval after a blink at which the initial aberration measurement is made.It has been suggested that tear film quality continues to improve and videokeratographic surface irregularity and surface indices begin to reduce over the first six seconds after a blink and deteriorate thereafter. Therefore, there may be a minimum in higher order aberrations a few seconds after a blink rather than immediately after the blink.
Posted by mehdi khanlari at 01:29 AM
May 06, 2003
Latest study results on the Implantable Miniaturized Telescope
Eyeworld May 2003 
Lane offered up 12-month interim results from the U.S. Phase I clinical trials. The trial included 15 patients enrolled at four centers. In one case, however, involving a patient with a ruptured capsule and vitreous loss, the IMT was not implanted. By the 12-month mark, 12 patients were available for follow-up.At 12 months, 10 of 13 (77%) of patients experienced a gain of 2 lines or more in either distance or near BCVA and 8 of 13 (62%) gained 3 or more lines in either distance or near BCVA. Mean ECD decreased by 7%, 13%, and 13% at 3, 6, and 12 months, respectively... At 12 months, ADL improved most in those patients who experienced an improvement in either distance or near BCVA of 2 or more lines “In terms of activities of daily living, there were statistically significant improvements in activities of daily living for all tasks,” For all tasks, including mobility, distance, and near acuity, there was more than a 60% mean improvement compared to baseline. The device has also proven very safe. “Endothelial cell counts have been essentially similar to what one would expect with an extracapsular cataract extraction,” “It’s going to be higher than phaco alone because we’re working with a much bigger incision.”Currently, a Phase II/III study of the IMT is under way at 30 centers throughout the country.
Posted by mehdi khanlari at 10:57 PM
New Haag-Streit pachymeter
Eyeworld May 2003
Posted by mehdi khanlari at 10:48 PM
Dislocated toric IOL : AChallenging Case
Eyeworld May 2003
One day postop, his vision was 20/60. At one week, it was 20/40. His refraction at that time showed a residual 1 D of cylinder at 30 degrees. “At 21 weeks postsurgery, he was referred by his optometrist to consider a YAG laser capsulotomy,”At the time of referral, the patient had variable visual acuity. His refraction showed 3 D of cylinder at 50 degrees with almost 4 D of myopia. “When we rechecked his refraction just a moment later, he had 1 D less of myopia and almost no cylinder. The cylinder axis of the lens rotated, there was movement of the lens in the vertical and horizontal planes, and there was complete nonfixation of the toric lens,Rivera decided to place a plano piggyback rep