Ophthalmology Review

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February 28, 2005

Corneal nerves recover slowly after LASIK

After LASIK, both the subbasal and the stromal nerves in the corneal flap recover slowly, and they do not return to their preoperative densities by 3 years postop, a confocal microscopy study found. Following an initial rebound to near-preoperative levels, the subbasal nerves appeared to decrease in number and density again between 2 and 3 years after LASIK, researchers found.
At the Mayo Clinic College of Medicine used a confocal microscope to study 17 corneas of 11 patients that had undergone LASIK for the correction of myopia of –2 D to –11 D. The corneas were examined before surgery and at 1, 3, 6, 12, 24 and 36 months after surgery.
The number and density of subbasal nerves decreased by more than 90% in the first month after surgery. They began to recover by 6 months postop, and by 2 years had reached a level not significantly different from preoperative levels. Between the second and third years postop, however, the number and density decreased again, so that by year 3 they were less than 60% of pre-LASIK levels.
In the stromal flap, most nerve fiber bundles were also lost after LASIK, and these began recovering by the third month, the researchers found. But by 36 months they had not reached their original numbers (P < .001).
No significant changes were seen in nerve number or density in the stromal bed posterior to the LASIK flap interface.
The study is published in the November issue of Investigative Ophthalmology & Visual Science.
posted by Dr.M.taherzadeh fromosnsupersite

Posted by mtaherzadeh at 12:05 AM | Comments (0)

February 27, 2005

Endothelial cell loss after autologous rotational keratoplasty

Graefe's Archive for Clinical and Experimental Ophthalmology January 2005

Purpose To investigate whether it may be possible to ascertain the influence of immunological factors on chronic endothelial cell loss by comparing chronic endothelial cell loss after autologous rotational penetrating keratoplasty and after homologous penetrating keratoplasty.
Methods For six patients who had undergone autologous rotational penetrating keratoplasty the relative annual loss of endothelial cells was calculated by means of an exponential regression analysis. The findings were compared with those in a homogeneous historical control group (53 patients undergoing homologous penetrating keratoplasty for keratoconus).
Results After autologous rotational keratoplasty relative annual loss of endothelial cells was 1.1%±2.6% (mean ± standard deviation). Relative annual loss of endothelial cells in the control-group was 16.7%±20.8%.
Conclusions The results of the study lead to the assumption that immunological influences might be the main cause for chronic endothelial cell loss after homologous penetrating keratoplasty.

Posted by mmiraftab at 10:33 AM | Comments (0)

Laser In Situ Keratomileusis in Patients With Posterior Polymorphous Dystrophy

Cornea. 24(2):230-232, March 2005

Purpose: To report short-term results of LASIK in 4 eyes with the vesicular form of posterior polymorphous dystrophy (PPMD).
Method: A review was performed of 2 patients with PPMD who underwent bilateral LASIK. Patients were asymptomatic at the time of presentation and had no prior ocular history. Preoperative measurements were made of uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), corneal pachymetry, and endothelial cell density (ECD). All 4 eyes underwent uneventful LASIK. Postoperative measurements of UCVA and BSCVA were performed at follow-up visits 1 day, 1 month, 3 months, and 1 year after surgery, along with pachymetry and ECD measurements at the 3-month and 1-year visits. Results were analyzed.
Results: At 1 year, all eyes had an UCVA equal to or better than 20/25 and BSCVA equal to or better than 20/20. There was a small mean endothelial cell loss (2.3%) at 1 year. No adverse events were experienced.
Conclusions: Short-term results indicate efficacy and safety of LASIK on eyes with posterior polymorphous dystrophy. Further study is needed to assess long-term outcomes in a larger study population.

Posted by mmiraftab at 09:57 AM | Comments (0)

February 26, 2005

Lateral rectus resections in divergence palsy: Results of long-term follow-up

Journal of AAPOS,Feb,2005
Retrospective review of 29 patients (age 35–83 years) with divergence palsy. Five subjects underwent unilateral lateral rectus resection between 4.5 and 5.5 mm on adjustable suture and 24 subjects underwent bilateral lateral rectus resection between 3 and 7 mm on adjustable sutures. Preoperatively, all patients had diplopia at distance and an esodeviation, which was greater at distance (mean 14.7 ± 5.1Δ) than at near (mean 4.7 ± 3.5Δ). Postoperative follow-up period ranged from 6 to 96 months (mean 38.7 ± 27.3 months). The angle of deviation at distance was significantly reduced to −0.1 ± 3.2Δ postoperatively (P < 0.0001). The angle of deviation at near reduced significantly to −2.2 ± 3.3Δ postoperatively (P < 0.0001). No patient was overcorrected for near. Two patients experienced recurrent postoperative diplopia at distance subsequently at 1 and 4 years, which was corrected with prism glasses and lateral rectus re-resection.
Conclusion: Lateral rectus resection in patients with divergence palsy is an effective and stable procedure in patients with divergence palsy over long-term follow-up periods, with minimal risk of overcorrections at near.

Posted by afarahi at 12:33 AM | Comments (0)

February 25, 2005

Bilateral medial rectus muscle recession for divergence insufficiency pattern esotropia

Journal of AAPOS,Feb,2005
This is a retrospective consecutive case series of eight patients treated for divergence insufficiency pattern esotropia with bilateral medial rectus muscle recessions. Age at presentation was 44 to 77 years (mean age, 60) and symptoms of diplopia at distance had been present between 3 and 30 years . Each patient had a manifest esotropia at distance and smaller or no deviation at near. The mean preoperative esodeviation was 20.4 prism diopters (range, 12 to 35) at distance and 5.4 PD (range, 0 to 18) at near with a mean distance-near difference of 15.0 PD. Bilateral medial rectus muscle recession of 3.0 to 4.25 mm (mean 3.5) was performed on each patient. The mean postoperative esodeviation at distance was 3.4 PD (range 0 to 10) and the mean near deviation was 1.8 PD exophoria (range, 8 PD exophoria to 10 PD esotropia) with a mean distance-near difference of 5.1 PD. Conclusions: Bilateral medial rectus muscle recession is an effective treatment for slowly progressive divergence insufficiency pattern esotropia in elderly patients. The reduction in the difference between the distance and near magnitudes of esodeviation afforded by this treatment suggests that a subtle loss of medial rectus muscle elasticity is the etiology.

Posted by afarahi at 11:17 PM | Comments (0)

Prospective Randomized Comparison of 2 Different Methods of 5% Povidone-Iodine Applications for Anterior Segment Intraocular Surgery

Archive of Ophthalmology. Feb.2005
In this prospective controlled trial, 200 eyes undergoing anterior segment intraocular surgery were randomized to control and study groups. All patients from both groups received topical ofloxacin and a povidone-iodine scrub of the periorbital area before the surgical procedure. The eyes in the control group received 2 drops of povidone-iodine on the conjunctiva preoperatively, whereas eyes in the study group had irrigation of the fornices with 10 mL of povidone-iodine. Conjunctival cultures were obtained at 4 separate time points before and after surgery. Twenty (26%) of 78 eyes in the study group had positive conjunctival cultures immediately prior to surgery compared with 40 (43%) of 94 eyes in the control group (P = .02). At the conclusion of the surgery, 14 (18%) of 78 eyes and 30 (32%) of 94 eyes had positive cultures in the study and control groups, respectively (P = .05).
Conclusion : Irrigation of the fornices with 5% povidone-iodine was associated with significantly fewer positive conjunctival cultures at the time of surgery compared with the application of 2 drops on the conjunctiva.

Posted by afarahi at 08:45 PM | Comments (0)

Clinical Evaluation of the New TGDc-01 "PRA" Palpebral Tonometer: Comparison with Contact and non-Contact Tonometry

Optometry & Vision Science. 82(2):143-150, February 2005

Methods. Fifty-eight right eyes of 58 young subjects were measured with each of the tonometers. Noncontact tonometry was performed first, followed by Goldmann and Perkins applanation tonometer (in random order), digital Tono-Pen XL, and finally TGDc-01 tonometer (sitting and supine position). Correlation analysis was used to evaluate the relationship between the Goldmann tonometer and the remaining tonometers used in this study. Plotting the difference between the methods against mean was also done to compare the tonometers. The hypothesis of zero bias was examined by a paired t-test. The 95% limits of agreement (LoA) were also calculated.
Results. TGDc-01 showed no statistical difference between the IOP measurements obtained in sitting and supine positions. A poor relationship between the TGDc-01 and Goldmann tonometer was found (r2 = 0.173; p = 0.001). Although the mean differences between Goldmann and Tonopen XL, Xpert, and TGDc-01 IOP measurements were statistically significant, the wider 95% LoA was observed when comparing the Goldmann and TGDc-01 tonometers. Computation of the 95% LoA resulted in a wide bias range when comparing the TGDc-01 with all the tonometers used in this study.
Conclusions. The TGDc-01 "PRA" tonometer was not comparable with the other techniques used in the study. The wide dispersion range of the values obtained shows low repeatability of the TGDc-01 for screening purposes. These results could be because of the technique of measurement and/or interindividual variables.

Posted by mmiraftab at 06:14 PM | Comments (0)

A technique to harvest Descemet’s membrane with viable endothelial cells for selective transplantation

American Journal of Ophthalmology Volume 139, Issue 2 , February 2005, Pages 325-330

Corneoscleral buttons of seven human donor eyes were mounted endothelial side up on an artificial anterior chamber. Keeping the endothelial side with its usual concavity, a manual trephination was made on the posterior surface with a 9.0-mm trephine, inside the Schwalbe line and just past the DM in depth. The chamber was filled with air, causing the endothelial side of the donor cornea to assume a convex configuration. The DM along with its endothelium was separated from the posterior stroma using a blunt cyclodialysis spatula. Drops of trypan blue 0.3% and alizarin red S 0.2% (n = 6) were applied. The stained DMs were examined under a light microscope and photographed to calculate the percentage of endothelial cell damage. Histology was done on the unstained cornea.
Results
The DM carrying endothelium was successfully removed from the posterior stroma in all seven eyes. Although the DM appears to be very friable, all samples were removed in toto without rupture. Vital staining showed a mean endothelial cell loss of 8.46% (standard deviation (SD) 6.9). Direct light microscopy demonstrated the preservation of endothelial cell morphology.
Conclusions
This technique appears to be a safe and straightforward method to harvest DM for endothelial cell transplantation. Further studies are underway to determine the optimal method of insertion of the obtained healthy DM with endothelial cells through small corneal incisions.

Posted by mmiraftab at 05:49 PM | Comments (0)

New Use for Wavefront Technology

Ophthalmology mangement Feb 2005

This new use, developed by San Diego-based Ophthonix, allows doctors to treat patients' higher-order aberrations without surgery, and the company says it also saves chair time.Part of this new system is the Z-View Aberrometer, which measures sphere, cylinder and axis, and higher-order aberrations. It then analyzes that data and creates a prescription -- all in about 1 minute.The other part of the system is the unique Ophthonix manufacturing process, which allows the creation of eyeglasses and contact lenses based on the prescription generated by the aberrometer.The iZon glasses will be manufactured by Ophthonix, while its partner, Optical Connection Inc., will manufacture the contact lenses, with Ophthonix being the distributor. The contact lenses will be referred to as the "iZon Wavefront-Guided Contact Lenses by Definition." The entire process is broken up into three steps. The first step is the capture of the wavefront measurement. In about 1 minute the device determines the patient's low and higher-order aberrations and generates a prescription. The prescription comes out as a bar code. The prescription is then sent to an Ophthonix lab where the lens programmer reads the digital prescription created by the Z-View and manufactures the lenses.The lenses are not molded or grounded; the manufacturing process does not touch the surface of the lens or remove material, it changes the actual optical properties of Ophthonix's patented material on a point-by-point basis.The material is deposited between a front and base lens surface. After the polymer is cured, the lens is programmed with a patented process that is comparable to burning a CD. The final index lens is completely customized to the individual patient. After manufacturing, the glasses are sent to the doctor's office.Jarvis notes that it will take a few days to manufacture the lenses, apply the premium coatings, and send the glasses or contact lenses to the practice. Patients and practices will have the option to have them overnighted, at cost.

Posted by mehdi khanlari at 04:41 PM | Comments (0)

Corneal Reinnervation 3 Years after LASIK

Ophthalmology Management Feb 2005
A study conducted at the Mayo Clinic College of Medicine in Rochester, Minn., and published in the November issue of Investigative Ophthalmology & Visual Science, used confocal microscopy to examine 17 corneas of 11 patients who had undergone LASIK for myopia from -2D to -11D. In these patients it was found that after LASIK, both the subbasal and stromal nerves in the corneal flap recovered slowly. It was also found that the subbasal and stromal nerves did not return to their preoperative densities by 3 years postoperatively, and that after an initial return to near-preoperative levels, the subbasal nerves appeared to decrease in number and density again between 2 and 3 years after LASIK.Researchers found that in the stromal flap most nerve fiber bundles were lost after LASIK, but began to recover by the third month. In later patient examinations it was found that by month 36 these fibers had not reached their original numbers. Researchers did not find any noteworthy changes in nerve number or density in the stromal bed posterior to the LASIK flap interface.Ophthalmology Management asked Marguerite McDonald, M.D., "This study further reinforces the decision made by many surgeons, including myself, to switch back to 100% surface ablation," she said. "One reason for our switch is that dry eyes are made significantly worse by LASIK, especially in older patients. LASIK is very successful in the vast majority of patients, but this study should help us to weed out -- in advance -- those patients who cannot safely undergo the reduction in corneal nerve population caused by LASIK. This study should also influence LASIK surgeons to more readily consider surface ablation (PRK, LASEK, or epi-LASIK) in older patients and any patient with the signs and/or symptoms of dry eye disease."

Posted by mehdi khanlari at 04:28 PM | Comments (0)

Optic disk ovality as an index of tilt and its relationship to myopia and perimetry

American Journal of Ophthalmology Volume 139, Issue 2 , February 2005, Pages 247-252

The study included 150 randomly recruited male subjects with myopia. In all cases, one eye was randomly selected, and subjective refraction, slit-lamp examination, applanation tonometry, gonioscopy, A-scan ultrasonography, funduscopy, and color optic disk stereo photography were performed. Disk ovality was assessed using the ratio of minimum to maximum disk diameter (index of tilt). A ratio of ≤ 0.8 was considered as significant disk tilt. Visual fields were tested using static automated threshold perimetry with two methods of optical correction: trial lenses and contact lenses.
Results
Of the total sample, 137 subjects completed the study. Mean age was 21.2 ± 1.1 year, and mean spherical equivalent was -6.36 ± 3.56 diopters. Mean ovality ratio was 0.83 ± 0.09; 55 subjects (40.2%) had significant tilted optic disks. Greater optic disk ovality (tilt) correlated with greater myopia (P = .009) and longer axial length (P = .009); 95.6% of subjects had normal visual fields with both methods of optical correction. Using multiple linear regression analysis, greater tilt was independently related to a higher mean defect on testing with trial lenses (P < .01).
Conclusions
Increased optic disk tilt was associated with higher myopia and reduced sensitivity on field testing. These factors are important in the assessment of glaucoma in patients with myopia.

Posted by mmiraftab at 01:21 PM | Comments (0)

Ocular higher-order aberrations in eyes with supernormal vision

American Journal of Ophthalmology Volume 139, Issue 2 , February 2005, Pages 225-228

Methods
Ocular HOAs were examined across a naturally dilated pupil with a diameter ≥ 6.0 mm in 70 eyes of 35 subjects with ≥ 20/15 UCVA (mean age 24.3 years ± 7.7 [SD]) using the Nidek OPD scan wavefront aberrometer. Root-mean-square (RMS) values of HOA, total spherical aberration (TSA), total coma (TC), and total trefoil (TT) were analyzed. Correlation analysis was performed to assess the association between ocular HOAs and age and the correlation of HOAs between right and left eyes.
Results
Mean RMS values were 0.334 ± 0.192 μm for HOA, 0.110 ± 0.077 μm for TSA, 0.136 ± 0.081 μm for TC, and 0.268 ± 0.220 μm for TT. There were no significant differences in the mean values of HOA, TSA, TC, and TT between right and left eyes. The Pearson correlation coefficient between right and left eyes for TSA was 0.764 (P<.0001). No significant correlation was found between right and left eyes for HOA, TC, and TT. No significant correlation was found between each of the ocular aberrations and age.
Conclusions
The amount of ocular HOAs in eyes with natural supernormal vision is not negligible, and is comparable to the reported amount of HOAs in myopic eyes.

Posted by mmiraftab at 01:18 PM | Comments (0)

February 24, 2005

Two-Year Follow-up of a 6-Month Randomized Trial of Atropine vs Patching for Treatment of Moderate Amblyopia in Children

Arch Ophthalmol.Feb.2005
In a randomized, multicenter (47 sites) clinical trial, 419 children younger than 7 years with amblyopia (20/40 to 20/100 in the affected eye) were assigned to receive either patching or atropine eye drops for 6 months. Between 6 months and 2 years, treatment was at the discretion of the investigator.
At 2 years, visual acuity in the amblyopic eye improved from baseline a mean of 3.7 lines in the patching group and 3.6 lines in the atropine group. The difference in visual acuity between treatment groups was small: 0.01 logMAR (95% confidence interval, –0.02 to 0.04). In both treatment groups, the mean amblyopic eye acuity was approximately 20/32, 1.8 lines worse than the mean sound eye acuity, which was approximately 20/20.
Conclusions : Atropine or patching for 6 months followed by best clinical care until 2 years produced similar improvement of moderate amblyopia in children between 3 and 7 years of age at enrollment. However, on average the amblyopic eye acuity was still approximately 2 lines worse than the sound eye.

Posted by afarahi at 09:51 PM | Comments (0)

CZM femto laser patent

Eurotimes Jan 2005
Carl Zeiss Meditec AG, Germany, and IMRA America Inc, USA, filed an international patent application for a femtosecond fiber laser with potential for use in refractive surgery.The application describes a high-repetition rate femtosecond fiber laser coupled to a high-speed scanner. Currently, ultraviolet excimer lasers are often used to photoablate the eye.According to the applicants of the patent this is a relatively a crude process given the size of the laser spot.The use of femtosecond laser pulses allows the spot size to be drastically reduced, allowing for a smoother shape.With a repetition rate of at least 50,000 pulses per second and a pulse length of less than 1 picosecond, the femtosecond laser should reduce the procedure time.

Posted by mehdi khanlari at 06:05 PM | Comments (0)

Cellular waste implicated in RP

Eurotimes Jan 2005
University of Utah geneticists report the discovery of gene mutations that impair the ability of photoreceptor cells to properly dispose of waste - and as a result cause retinitis pigmentosa.The mutations inhibit the function of a protein complex made up of carbonic anhydrase 4 (CA4) and Na+/Bicarbonate Co-transporter1 (NBC1) from doing its job of controlling pH balance. Excessive acid build-up leads to the death of photoreceptor cells and the onset of RP.The finding should spur the search for a pharmaceutical intervention to counteract the effect of the gene mutations. However, the discovery also raises concerns that carbonic anhydrase inhibitors may adversely affect vision.

Posted by mehdi khanlari at 06:01 PM | Comments (0)

Not all pre-YAG assessment techniques

BMC Ophthalmology Dec 24 2004
Not all pre-YAG assessment techniques useful. Some of the common evaluation methods used prior to Nd:YAG capsulotomy have no clinical utility a new study concludes.T.Aslam MD and colleagues compared several simple pre-operative measures in estimating the potentia or a visually successful capsulotomy in 24 patients.These included pre-operative measures of glare with BAT tester, visibility of posterior pole and grading of posterior capsular pearls and fibrosis seen at slit lamp. Pearls at slit lamp and poor posterior pole visualisation did correlate with improvements in visual acuity and contrast sensitivity after capsulotomy. However, the amount of fibrosis visible at slit lamp and glare assessment were not correlated with vision improvements after laser.The researchers encourage clinicians to consider the implications of the study when considering the various preoperative tests used in assessing potential benefit from Nd:YAG lase capsulotomy.

Posted by mehdi khanlari at 05:37 PM | Comments (0)

February 22, 2005

Pre-loaded injection system makes cataract surgery easier and safer

OSN 2005
Being pre-loaded, the implant is completely sterile and it is delivered to the eye in perfectly aseptic conditions. There’s no contact with the lens during the procedure, and this eliminates the risk of contamination with bacteria or foreign bodies such as talc, dust or blood. The Premier pre-loaded, single-use injector manufactured by Corneal is a safe, easy-to-use and innovative system for IOL implantation. The Premier injector is pre-loaded with the Corneal ACR6D SE IOL.

Posted by kjalali at 09:02 PM | Comments (0)

A new system for the automatic estimation of endothelial cell density in donor corneas

British Journal of Ophthalmology 2005;89:306-311

Aims: The problem of automatic estimation of endothelial cell density from microscopy images in donor corneas was addressed.
Methods: The spatial frequencies contained in digital endothelium images are extracted with a two dimension discrete Fourier transform (DFT) technique. A circular band in the DFT of the images is shown to contain the frequency information related to the cell density. An algorithm for reliably recovering this spatial frequency information and for extracting from it an estimate of endothelial cell density has been developed and implemented in a computer program. An evaluation was performed on a data set containing 100 donor corneas, by comparing automatic values with manual counts performed by three eye bank experts on two images for each cornea.
Results: The mean difference of automatic densities v manual ones was 14 cells/mm2 (0.9%), with a standard deviation of 119 cells/mm2 (5.1%) and mean absolute difference of 92 cells/mm2(3.9%). The ANOVA based overall inter-rater reliability was 0.935. The algorithm was also capable of identifying all non-processable images. Running times were in the order of 1–2 seconds per image.
Conclusion: A new algorithm was developed for the fully automatic estimation of endothelial cell density. The results of a clinical evaluation on 100 corneas suggest that it is capable of reliably estimating endothelium cell density in donor corneas.

Posted by mmiraftab at 08:59 PM | Comments (0)

Manual LASEK without the use of alcohol can be performed in selected cases

OSN 2005
Surface refractive surgical procedures such as LASEK and PRK have been regaining popularity in the past few years, as they seem better suited for custom treatment. LASEK has reduced the risk of the major concerns of PRK, namely haze and postoperative pain. However, the potentially toxic effects of the alcohol used to detach the epithelium have been a cause of concern for some surgeons. Hence, alternative methods of automated epithelial sheet separation, which use special epithelial microkeratomes such as the Centurion Epi-Edge epikeratome (Norwood Abbey Ltd.) and the Epitome epi-LASIK system (VisiJet), were developed. These systems do work, but they have the disadvantage of being extremely expensive. A technique, which have named LASEKSAM (LASEK sans alcohol manuel, in French), is simple, safe and inexpensive, and takes into account the variability of epithelial adhesion in patients’ eyes. Surgery begins with the surgeon marking the epithelium using a simple marker around the treatment area. The epithelial flap is cut along this line using a sharp microtip needle. With the same instrument, The surgeon tests the adherence of the epithelium along the edge. By testing epithelial adherence we can select the cases in which the flap can be performed without using the alcohol. We can start at the point where the epithelium is more loosely attached and lift the edge with a spatula. Then we penetrate under the flap with a larger spatula and progressively separate the epithelial flap from the stromal bed. The epithelial flap obtained with this method is thinner and more delicate than LASEK flaps. Once lifted, it dries up quickly, and it should be moistened and protected with a drop of viscoelastic. This maneuver can also be slightly cumbersome because the flap is very thin and might get torn. However, even if the flap is not perfect, it will give the cornea enough protection as long as the center is covered. At the end, a soft contact lens is applied and left in place for 4 days. The corneas treated with this method look clear and transparent at day 1. Compared with LASEK, there was less epithelial exfoliation, and the viability of the epithelial cells was apparent. At the beginning of the learning curve, this method of creating the flap manually and without alcohol takes 5 to 10 minutes. With more experience, 3 to 5 minutes is sufficient.In cases in which the epithelium is too tightly adherent to perform the LASEKSAM procedure, we can uses alcohol at a lower concentration than the usual 18% to 20%. A 10% concentration is sufficient to detach the epithelium, but you need to leave it in place for 1 minute rather than the usual 30 seconds. This is because the lower alcohol content makes the solution less capable of penetrating the tissues down to the stromal layer. On the other hand, a 10% solution causes no damage to the epithelium, which looks just like it does in the procedure without alcohol and very different from the epithelium which has been detached with an 18% alcohol solution. A clinical study comparing the results of LASEKSAM without alcohol or with a 10% alcohol solution to LASEK with 18% alcohol solution is currently ongoing.

Posted by kjalali at 08:47 PM | Comments (0)

Topographic and biomechanical differences between hyperopic and myopic LASIK

JCRS JAN 2005
USA,To evaluate the size, shape, and uniformity of the videokeratographic functional optical zone (FOZ) after laser in situ keratomileusis (LASIK) in 2 cohorts of patients with equivalent amounts of preoperative myopic or hyperopic astigmatism.
Eyes with M or H astigmatism (n=27 in each group) that had LASIK with the Visx Star S3 laser were retrospectively selected to match for level of preoperative refractive error. Slit-scanning videokeratography was performed preoperatively and 6 months postoperatively and analyzed using custom software. The FOZ was calculated by analyzing refractive power maps using a region-growing algorithm. Difference maps were generated from slit images and compared for interval change in corneal elevation, tangential curvature, and refractive power. The difference maps were also averaged (mean difference maps) for each target population. A Zernike decomposition of corneal first-surface elevation was performed to compare postoperative values with baseline parameters.

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Conclusions:Hyperopic eyes, on average, had larger topographic FOZs after LASIK, but with less uniformity of curvature and power change than myopic eyes.Hyperopic LASIK, which involves more transition points along the ablation diameter, produced a less uniform topographic FOZ than typical myopic treatments. Less predictable biomechanical changes from the circumferential release of tension on collagen bundles after midperipheral hyperopic ablation and greater variation in beam centration and the angle of incidence may contribute to the greater variability in corneal curvature and power in hyperopic LASIK than in myopic LASIK.

Posted by alireza habibollahi at 12:48 AM | Comments (0)

Differences in nasal and temporal responses of the cornea after PRK

JCRS JAN 2005
Italy;To examine the differences in the biomechanical response of the
peripheral regions of the cornea after PRK.
Preoperative and 1-, 3-, 6-, and 12-month postoperative corneal topographies of 70 eyes that had PRK with the Technolas 217C excimer laser (Bausch & Lomb) were obtained. The eyes were divided into 4 groups according to the preoperative spherical equivalent refraction. Preoperative and follow-up topographic data were imported into custom software that computed the average composite corneal map and difference maps in each group to scientifically evaluate the corneal response to the surgery. The software was also used to analyze regional corneal changes after the laser ablation. Corneal peripheries up to 9.0 mm were evaluated.
Conclusions
To refine modeling of the cornea, the different regional anatomic features and biomechanical responses must be considered. Modifying existing ablation algorithms to compensate for the differences between nasal and temporal corneal flattening of the preoperative corneal surface and between the nasal and temporal responses may improve the postoperative corneal shape and quality of peripheral optics.

Posted by alireza habibollahi at 12:35 AM | Comments (0)

Corneal power, thickness, and stiffness: Results of a prospective randomized controlled trial of PRK and LASIK for myopia

JCRS JAN 2005
Denmark,To compare the short-, medium-, and long-term changes in corneal optical power and corneal aberrations, central corneal thickness, and corneal “stiffness” assessed by pneumotonometry readings in patients having LASIK or PRK for myopia.
Conclusions
Differences between LASIK and PRK related to time-dependent events affecting corneal shape and structural integrity were present. Peripheral changes in flap hydration in LASIK eyes and epithelial and/or stromal thickening in PRK eyes appeared to be the most important factors in optical power changes in the first year after treatment. The changes in apparent IOP suggest that some interlamellar healing occurred during the first year after LASIK. After LASIK and PRK, corneal bending stiffness seemed permanently decreased, although some restiffening may occur in PRK eyes in the long term

Posted by alireza habibollahi at 12:14 AM | Comments (0)

February 21, 2005

Tissue damage at anterior capsule edges after continuous curvilinear capsulorhexis, high-frequency capsulotomy, and erbium:YAG laser capsulotomy

JCRS JAN 2004
Austria,To compare the effect of erbium:YAG laser photocapsulotomy (ELC), continuous curvilinear capsulorhexis (CCC), and high-frequency capsulotomy (HFC) on anterior capsule edges using light microscopy (LM) and transmission electron microscopy (TEM).
Conclusions: Of the 3 techniques, CCC produced the mildest tissue damage. The histological damage at ELC edges was relatively mild and intermediate compared with that seen at CCC and HFC edges. These observations suggest that ELC is an appropriate option for anterior capsulotomy in cataract surgery.

Posted by alireza habibollahi at 11:43 PM | Comments (0)

Photoelectric Dye-coupled Polyethylene Film as a Prototype of Retinal Prostheses
Artificial Organs
Volume 29 Issue 1 Page 53 - January 2005
doi:10.1111/j.1525-1594.2004.29010.x

Photoelectric dyes, which absorb light and convert photon energy to electric potentials, have been previously shown to stimulate retinal neurons in culture. In this study, a photoelectric dye was coupled to a polyethylene film surface and tested in vitro using retinal tissues from chick embryos at the 12-day embryonic stage, at which time outer segments of retinal photoreceptor cells have not yet developed. Carboxyl moieties were introduced to a polyethylene film surface by fuming nitric acid, and then a photoelectric dye, 2-[2-[4-(dibutylamino)phenyl]ethenyl]-3-carboxymethylbenzothiazolium bromide, was coupled to the film through amide linkage. Intracellular calcium elevation was observed with Fluo-4 in retinal tissues placed on the dye-coupled polyethylene film, in contrast to retinal tissues which had no contact with the film. The response was inhibited by calcicludine, a voltage-gated calcium channel blocker, and also by extracellular calcium depletion. The photoelectric dye, coupled to the polyethylene film surface, absorbed light under a dissecting microscope and stimulated neurons in retinal tissues, showing that the dye-coupled film could be used as a prototype of retinal prostheses.

Posted by saliakbari at 10:11 AM | Comments (0)

Biomechanical Characterization of Human Amniotic Membrane Preparations for Ocular Surface Reconstruction
Ophthalmic Research 2004;36:341-348

Low-dose electron beam-irradiated amnion appeared to maintain desirable elastic characteristics in transition from a dry to rehydrated state and may thus provide an easy-to-manipulate transplant tissue for ocular surface reconstruction. Moist nonirradiated and thawed medium-frozen tissues, however, may provide surgical advantages as they required greater forces to rupture.

Posted by saliakbari at 10:07 AM | Comments (0)

February 20, 2005

Tissue response to laser ablation

Eurotimes Feb 2005
....SEVERAL new approaches to achieving optimal results in corneal refractive surgery are now emerging as a result of an improved understanding of tissue response to laser ablation and recent advances in aberrometry and laser technology. Prof Marshall noted that in the current understanding of corneal architecture, the corneal lamellae are composed of collagen fibres running from limbus to limbus.The collagen fibres are 30 nm in diameter and extend over 12 mm arcs.The structure ist he scale equivalent of cables 1.0 cm in diameter stretched over an arc of 4 km, he said.In the centre of the cornea, the fibres cross perpendicularly but towards the periphery they cross increasingly obliquely. When a cornea undergoes laser ablation the fibres are snapped, undermining the integrity of lamellar mesh and altering the shape of the cornea, independent of the ablation profile. In LASIK the microkeratome increases the number of fibres cut by around 50-fold, further undermining the cornea’s structural integrity, Dr Marshall pointed out. Following LASIK procedures, the flap is held to the surface of the cornea by fibronectin and tenascin.

Posted by mehdi khanlari at 08:12 PM | Comments (0)

Cortical cataracts have genetic link, posterior subcapsular cataracts do not

OSN Feb 2005
Genetics have a significant effect on the development of cortical cataracts, but not posterior subcapsular cataracts, a study by researchers at Johns Hopkins University suggests The researchers studied 321 participants already enrolled in the Salisbury Eye Evaluation (SEE) study and compared results with 453 of their siblings. The siblings had a mean age of 72.6, while the study participants had a mean age of 78 years. The difference in mean age was statistically significant.After adjusting for environmental factors such as use of tobacco and alcohol, use of medications such as estrogens and steroids, lifetime exposure to ultraviolet-B light, serum antioxidants, history of diabetes, blood pressure and body mass index, the researchers found that cortical cataract had a magnitude of heritability of 24%. The magnitude of heritability of PSC, 4%, was not statistically significant.Older age, female gender, history of diabetes and black race increased the odds of cortical cataract development; higher levels of provitamin A were found to be protective. Diabetic history and steroids increased the odds of PSC development.

Posted by mehdi khanlari at 03:56 PM | Comments (0)

February 18, 2005

5-year follow-up of LASIK for hyperopia

Ophthalmology,Feb,2005
Patients who had been treated for hyperopia (33 individuals, 47 eyes) attended follow-up 5 years after surgery. The preoperative mean spherical equivalent at the spectacle plane was +3.58 D (range, +0.75 to 7.00 D), and the attempted mean spherical correction at the corneal plane was +3.18 D (range, +1.00 to +6.00 D).At 5 years, for treatments between +1.00 to +3.00 D, 71.0% of eyes were within ±1.00 D of the intended correction, and for treatments between +3.5 to +6.0 D, 37.5% of eyes were within ±1.00 D of intended correction. From 12 to 54 months after surgery for all patients, there was a hyperopic shift of +0.53 D (range, −0.13 to +3.13 D), with 51.1% of eyes experiencing an increase of +0.50 D or more and 27.7% of eyes showing a hyperopic shift of more than +1.00 D. This hyperopic shift was +0.67 D (range, 0 to +1.125 D) for patients younger than 40 years of age and +0.44 D (range, −1.33 to +1.50 D) for patients between 43 and 55 years of age.
Conclusions:LASIK was moderately effective for the correction of low degrees of hyperopia. However, there was regression throughout the 5-year follow-up that was greater than would be expected as a result of aging. Long-term stability of hyperopic LASIK refractive corrections, therefore, is uncertain.

Posted by afarahi at 08:36 PM | Comments (0)

Intraocular pressure and systemic blood pressure: longitudinal perspective: the Beaver Dam Eye Study

BJO,March,2005
This was a population based study of people 43–86 years old living in Beaver Dam, Wisconsin. Measurements at baseline (1988–90) and 5 year follow up of systemic blood pressures, intraocular pressures, and history of use of blood pressure medications.
Intraocular pressures were significantly correlated with systolic and diastolic blood pressures at both baseline and follow up. There were significant direct correlations between changes in systemic blood pressures and changes in intraocular pressure. There was a 0.21 (95% CI: 0.16 to 0.27) mm Hg increase in IOP for a 10 mm Hg increase in systolic and 0.43 (0.35 to 0.52) mm Hg increase in IOP for a 10 mm Hg increase in diastolic blood pressure. Further adjustment for diabetes and medication use did not alter these associations. Decreased systolic or diastolic blood pressures of more than 10 mm Hg over 5 years were significantly associated with decreased IOP.
Conclusions: Reduced systemic blood pressure is associated with reduced intraocular pressure. This finding should be evaluated in other studies, especially with respect to the possibility of resultant decreased risk of open angle glaucoma.

Posted by afarahi at 08:27 PM | Comments (0)

Transpalpebral tonometry: reliability and comparison with Goldmann applanation tonometry and palpation in healthy volunteers

BJO,March,2005
TGDc-01 is a new, portable, transpalpebral tonometry device. The aim of this study was to evaluate the reproducibility of this method, including intraobserver and interobserver deviations, and to compare the results with those of Goldmann applanation tonometry and palpation of intraocular pressure (IOP).
Conclusion: Interobserver deviations using TGDc-01 tonometry and intraindividual deviations between TGDc-01 tonometry, Goldmann applanation tonometry, and palpation of IOP were found to be clinically relevant. Thus, according to our results TGDc-01 could not be established as a substitute or diagnostic alternative method for Goldmann applanation tonometry. But as deviations between TGDc01 and Goldmann turned out smaller than between palpation of IOP and Goldmann, TGDc-01 seems to provide a better choice for tonometry in patients, in whom Goldmann applanation tonometry is not possible.

Posted by afarahi at 08:19 PM | Comments (0)

The LaFaci Surgical System

Ophthalmology Management Jan 2005
The LaFaci Surgical System creates a sanitary environment and offers an alternative way to perform many of the steps involved in LASIK procedures.The system consists of a handpiece; a surgical cart that includes a pivoting instrument tray, a tubing swing arm, and a bottle hanger bracket; a guarded plume evacuation switch; a guarded air/irrigation/aspiration (AIA) foot control; sterile and nonsterile disposable tubing; and smoke/fluid collection accessories, which include a fluid canister and plume smoke filter.LaFaci, short for LASIK facilitator, was developed by Leon LaHaye M.D.,
LASIK With LaFaci
Surgery with LaFaci begins with the placement of the handpiece on the eye. This should be done directly following the keratotomy but prior to lifting the flap. The handpiece is kept in place by an anatomically supported platform and is manually applied by the surgeon. While it isn't necessary for anyone besides the surgeon to hold the handpiece during the procedure, a technician can hold it.

Once in place, the handpiece facilitates several functions:

► Its conformed fit provides a means of controlling eye movements relative to the handpiece.

► The handpiece can suppress stromal bleeding caused by the keratotomy. The handpiece is designed to provide 360 degrees of nontraumatic pressure on the limbal ciliary vessels therefore allowing for hemostasis.

► Once the flap is lifted, the system's handpiece provides a non-metallic platform to support the flap. The platform is made of an FDA-approved polymer that has passed laboratory reprocessing and sterility validation testing.

► During LASIK, when fluids start to build up, surgeons use sponges to dry the stroma. The LaFaci provides a foot-switch-activated evaporation feature that provides air to the surgical field. The system delivers a uniform, symmetrical, sterile, laminar airflow to the stromal bed at a rate of 0.5 ml/sec to remove excess fluid.

► During the excimer laser phase of the procedure, the LaFaci handpiece removes the laser plume and particles with a laminar vacuum flow through seven ports within the handpiece. This function minimizes vertical plume and particle exposure, alleviating potential health issues and toxic odors.

► As irrigation is used at various times throughout LASIK, the LaFaci system streamlines the process by having the ability to hydrate the surgical field and then simultaneously aspirate excess fluids. The irrigation system is linear-controlled and sterile. This feature is controlled by a foot pedal.

► The LaFaci aspiration ports are designed to remove fluids from the lowest point within the cylinder body of the handpiece. The design of the port will prohibit any obstruction from conjunctival
tissue.

► Upon completion of the laser treatment, the platform that supports the flap during surgery will pivot and rotate, essentially flipping over, so that the flap will reposition onto the stromal bed.

► Lastly, the system will aid with flap adherence through the release of air from the handpiece. This may decrease the amount of time traditionally used by surgeons to observe flap adherence from minutes to seconds according to Dr. LaHaye

Posted by mehdi khanlari at 07:21 AM | Comments (0)

Stem Cells Can Preserve Vision

Ophthalmology Management Jan 2005
In a groundbreaking study, researchers from Harvard's Schepens Eye Research Institute have shown that transplanted stem cells can preserve, and even improve, vision in eyes damaged by retinal disease.
The researchers said results of a mouse study demonstrated that transplanted stem cells can develop into new retinal cells, prevent the death of "at risk" retinal cells, and improve the vision of treated mice. The results were published in the November issue of Investigative Ophthalmology and Visual Science."These findings hold great promise for potential treatments for people suffering from macular degeneration, diabetic retinopathy and other retinal diseases," To test whether the mice with transplanted stem cells could see better, the team then placed them and a group of nontreated control mice in separate dark cages and flashed a series of increasingly lower level lights at both groups over a period of time. Being photophobic, mice stop their normal activity when they detect light. The researchers took advantage of this natural response and found that the mice with the transplanted cells continued to respond to the light as it reached its lowest levels. The control mice did not.The team is now investigating the use of stem cells in pigs, whose eyes are larger and more like human eyes.

Posted by mehdi khanlari at 07:14 AM | Comments (0)

February 17, 2005

ACCUPACH V

Accutome says the AccuPach V is extremely accurate and has several new and unique features. AccuPach V provides a corrected IOP based on corneal thickness measurements. It has a voice output. The AccuPach V automatically captures and stores up to nine measurements for each eye. It has a touch screen and an optional printer for ease of use. It displays measured corneal thickness, entered IOP, corrected IOP, and the average for all stored measurements

Posted by mehdi khanlari at 11:17 PM | Comments (0)

Albumin and Transthyretin as Risk Factors for Cataract

Archives of ophthalomology February 2005
Conclusions This study is suggestive of an association of protein undernutrition with increased risk of cataract. Low protein intake may induce deficiencies of specific amino acids that are needed to maintain the health of the lens, or other nutritional deficiencies, particularly niacin, thiamin, and riboflavin

Posted by mehdi khanlari at 10:55 PM | Comments (0)

Randomized prospective clinical study comparing induced aberrations with IntraLase and Hansatome flap creation in fellow eyes

Journal of Cataract & Refractive Surgery Volume 31, Issue 1 , January 2005, Pages 97-105

This randomized prospective study comprised 9 patients (18 eyes) treated with a 2-step LASIK procedure: lamellar keratectomy with a Hansatome microkeratome (Bausch & Lomb) or the IntraLase femtosecond laser in fellow eyes followed by non-wavefront-guided (standard) excimer laser treatment with the Technolas 217A (Bausch & Lomb) excimer laser 10 weeks later. Fellow eyes were matched to within 0.75 diopter (D) sphere and 0.50 D cylinder. Patients were followed for 3 months after excimer laser treatment. Preoperative and post-flap creation wavefront aberrometry using a Hartmann-Shack aberrometer and manifest refraction were compared between the 2 groups. The same tests were performed 3 months after excimer laser ablation.
Results
Statistically significant changes were seen in defocus wavefront aberrations after Hansatome (P = .004) and IntraLase (P = .008) flap creation. A hyperopic shift in manifest refraction was noted in the Hansatome group after the creation of the corneal flap (P = .04); no statistically significant changes in manifest refraction were seen in the IntraLase group. Statistically significant changes in total higher-order aberrations (HOAs) (trefoil and quadrafoil Zernike terms) were seen after flap creation in the Hansatome group (P = .02). No significant changes in HOAs were noted after flap creation in the IntraLase group. After the flap was relifted and standard excimer laser ablation was performed, a statistically significant increase in coma occurred in the Hansatome group (P = .008). Standard refractive outcomes in the 2 groups were similar.
Conclusions
The creation of the LASIK flap alone can modify the eye's optical characteristics in low-order aberrations and HOAs. A significant increase in HOAs was seen in the Hansatome group but not in the IntraLase group. This may have significant clinical implications in wavefront-guided LASIK treatments, which are based on measurements made before flap creation

Posted by mmiraftab at 08:38 PM | Comments (0)

Femtosecond laser versus mechanical keratome flaps in wavefront-guided laser in situ keratomileusis:Prospective contralateral eye study

Journal of Cataract & Refractive Surgery Volume 31, Issue 1 , January 2005, Pages 120-126

In a prospective contralateral-eye study performed under institutional review board supervision, 51 consecutive patients (102 eyes) had bilateral wavefront-guided LASIK for myopia using the Alcon LADARVision laser. One eye of each patient was randomized to have the flap created with the IntraLase femtosecond laser and the other flap using a standard compression head Hansatome microkeratome. All other treatment parameters were the same.
Results
The IntraLase group had significantly better mean uncorrected visual acuity (UCVA) at all intervals from 1 day to 3 months postoperatively. The mean spheroequivalent at 3 months was more myopic with the Hansatome (−0.34 diopter [D] ± 0.28 [SD]) than with the IntraLase (−0.19 ± 0.24 D) (P<.01). The mean residual astigmatism at 3 months was also significantly higher in the Hansatome group than in the IntraLase group (0.32 ± 0.25 D and 0.17 ± 0.20 D, respectively) (P<.01). The differences in UCVA persisted after spheroequivalent outcomes were controlled for but equilibrated when the analysis was modified to control for manifest postoperative astigmatism. Aberrometry showed significantly higher astigmatism and trefoil in the Hansatome group. Recovery of corneal sensation and epithelial integrity was similar between groups.
Conclusions
The statistically better UCVA and manifest refractive outcomes after LASIK with the IntraLase femtosecond laser may be the result of differences in postoperative astigmatism and trefoil. These findings are consistent with previous findings of better astigmatic outcomes with the IntraLase laser and may have clinical significance for wavefront-guided treatments.

Posted by mmiraftab at 08:35 PM | Comments (0)

Influence of corneal biomechanical properties on intraocular pressure measurement

Journal of Cataract & Refractive Surgery Volume 31, Issue 1 , January 2005, Pages 146-155

The model assumed an overall resultant pressure that was based on the summation of the applanation pressure, the true IOP, and the surface tension caused by the tear film to determine the final deformation of the corneal apex during IOP measurement. Corneal resistance was varied according to the cornea's biomechanical properties, thickness, and curvature, and the effect of each variable on the accuracy of IOP tonometry readings was examined quantitatively.
Results
The model demonstrated that tonometry readings do not always reflect true IOP values. They deviate when corneal thickness, curvature, or biomechanical properties vary from normal values. Based on the model, predicted IOP readings have a 2.87 mm Hg range resulting from the variation in the corneal thickness in the normal population and a 1.76 mm Hg range from the variation in the corneal radius of curvature. Considering that Young's modulus of the corneal varies from 0.1 to 0.9 MPa in the normal population, the model predicts tonometry IOP readings will have a range of 17.26 mm Hg because of the variation in this corneal biomechanical parameter alone.
Conclusions
The simulation based on the model demonstrated quantitatively that variations in each corneal variable cause errors in tonometry IOP readings. The simulation results indicate that differences in corneal biomechanics across individuals may have greater impact on IOP measurement errors than corneal thickness or curvature.

Posted by mmiraftab at 08:24 PM | Comments (0)

Corneal modeling of keratoconus by conductive keratoplasty

Journal of Cataract & Refractive Surgery Volume 31, Issue 1 , January 2005, Pages 190-197

We evaluated the effect of conductive keratoplasty (CK) applications for corneal modeling to treat keratoconus or post-laser in situ keratomileusis (LASIK) corneal ectasia in 3 patients. Treating keratoconus with CK applications resulted in more regular topography with visual improvement.

Posted by mmiraftab at 08:16 PM | Comments (0)

Transient keratectasia caused by intraocular pressure elevation after laser in situ keratomileusis

Journal of Cataract & Refractive Surgery Volume 31, Issue 1 , January 2005, Pages 202-204

Transient keratectasia developed in association with a marked intraocular pressure (IOP) elevation in a 26-year-old man who had laser in situ keratomileusis (LASIK) for myopia of −9.0 diopters. The keratectasia subsided promptly after the IOP was normalized by an intravenous administration of mannitol. Keratectasia did not recur. Intraocular pressure elevation can cause keratectasia in a structurally compromised cornea after LASIK.

Posted by mmiraftab at 08:03 PM | Comments (0)

February 15, 2005

Effect of 1-piece and 3-piece AcrySof intraocular lenses on the development of posterior capsule opacification after cataract surgery

JCRS NOV 2004
United Kingdom,To evaluate the effect of 1-piece and 3-piece hydrophobic acrylic IOLs on PCO after cataract surgery.
A series of 131 patients having cataract surgery had implantation of an acrylic 1-piece (SA30AL) or an acrylic 3-piece (MA30BA) IOL (AcrySof®, Alcon). Surgery was performed according to standardized protocol by a single surgeon at each hospital. Posterior capsule opacification was assessed using digital retroillumination photography. All images were analyzed at a single center according to a standard protocol. Data were analyzed 6 months and 1 year after surgery.
Conclusion: There was no evidence of a difference in the area of PCO after cataract surgery between 1-piece and 3-piece IOLs, which were otherwise matched for material and lens geometry.

Posted by alireza habibollahi at 11:19 PM | Comments (0)

Safety and efficacy of a dexamethasone anterior segment drug delivery system in patients after phacoemulsification

JCRS NOV 2004
UK,To compare the safety and efficacy of the Surodex® dexamethasone anterior segment drug delivery system (Oculex Pharmaceuticals, Inc.) and dexamethasone 0.1% eyedrops (Maxidex®) in patients with inflammation after cataract surgery.
Methods: This comparative single-masked parallel-group study comprised 1 eye of 19 patients having phaco-IOL. The Surodex group had the dexamethasone drug delivery system inserted into the anterior chamber (AC) angle during surgery and was treated with saline eyedrops (Isopto Plain®) for 4 weeks. The control group had no drug delivery system or a placebo inserted at surgery and were treated with dexamethasone 0.1% eyedrops for 4 weeks. A Kowa FM-500 laser flare meter was used to objectively measure AC flare, the main outcome measure. Slitlamp biomicroscopy to grade AC flare and cells, intraocular pressure measurement, and corneal endothelial specular microscopy, performed up to 60 days after surgery, were the secondary outcome measures. The Surodex group had safety follow-ups after completion of the initial study period.
Conclusion: Surodex appeared to be as effective as dexamethasone 0.1% eyedrops in controlling intraocular inflammation after cataract surgery by phacoemulsification, and both methods had a similar safety profile.

Posted by alireza habibollahi at 11:12 PM | Comments (0)

Macular alterations after small-incision cataract surgery

JCRS NOV 2004

Portugal,To characterize macular edema that occurs after uneventful cataract surgery.
32 eyes of 32 patients had uneventful phacoemulsification with implantation of a foldable intraocular lens. Postoperatively, patients were examined at 3, 6, 12, and 30 weeks. The examinations included retinal leakage analysis (Zeiss CSLO), optical coherence tomography (Humphrey Instruments), and retinal thickness analysis (Talia Technology, Ltd.). Results were compared with those in a control group comprising healthy subjects.
Conclusion: Macular edema after cataract surgery occurred primarily in the central region of the macula and was associated with the presence of leaking sites, which were located predominantly in the vascular regions of the central macula.

Posted by alireza habibollahi at 10:55 PM | Comments (0)

‘Essential’ allergy protein found in conjunctiva

OSN 2/14/2005

A protein found in the eye may play a critical role in how the initial early allergic response develops, researchers at the University College London said.Prof. Santa Jeremy Ono and colleagues have determined that macrophage inflammatory protein-1a (MIP-1a), found in the conjunctiva, plays a crucial role in first 24 hours of an allergic response, as well as in the later inflammatory phase.Prof. Ono’s study concluded that MIP-1a is “essential in the initial stages of development of an allergic response” in the conjunctiva, according to a press release from University College.Medications that block the protein from binding to its receptors might help treat ocular allergy and other allergic diseases, the team suggested in the online edition of Journal of Clinical Investigation.

Posted by mmiraftab at 02:36 PM | Comments (0)

February 13, 2005

New technique for cataract surgery

Pulsatome from visijet
The Pulsatome creates a heated pulse of saline solution that emulsifies cataracts, breaking them into small pieces. The Pulsatome simultaneously flushes out the emulsified tissue thereby removing it from the eye.

This process ensures quick and safe removal of the crystals that form on the eye that create the cataract. The Pulsatome is easier to use than current ultrasound cataract devices, and unlike current methods, does not require a needle to be inserted into the lens. FDA approval is expected for the Pulsatome in early 2005.

Posted by saliakbari at 12:05 PM | Comments (0)

Rate of axial growth after congenital cataract surgery
American Journal of Ophthalmology
Volume 138, Issue 6 , December 2004, Pages 915-924

Rate of axial growth is higher in children ≤ 1 year and increases until the second year after surgery. Unilateral pseudophakia revealed accelerated growth compared with bilateral pseudophakia. Visual axis obscuration does not influence rate of axial growth.

Posted by saliakbari at 11:47 AM | Comments (0)

Degree of angle closure and the intraocular pressure–lowering effect of latanoprost in subjects with chronic angle-closure glaucoma

Ophthalmology Volume 112, Issue 2 , February 2005, Pages 267-271

To examine the relationship between the configuration of the drainage angle and intraocular pressure (IOP)–lowering efficacy of latanoprost in subjects with chronic angle-closure glaucoma (CACG).
Design
Prospective observational case series.
Participants
One hundred thirty-seven Asian subjects with CACG.
Methods
Study subjects had participated in a 12-week, randomized, double-masked study that assessed the IOP-reducing effect of latanoprost. Chronic angle-closure glaucoma was defined as optic neuropathy with or without a visual field defect, an anterior chamber angle in which the trabecular meshwork was not visible for at least 180° on gonioscopy, and evidence of peripheral anterior synechiae (PAS) in association with a chronically elevated IOP. Static and dynamic gonioscopy was performed at baseline. The angles were graded in each quadrant according to the Shaffer scheme, and the number of clock hours of PAS was recorded. The change in daily IOP (defined as the mean of the 9:00 AM and 5:00 PM IOP time point values) from baseline to week 12 was analyzed and correlated with mean angle width and extent of PAS.
Results
One hundred thirty-seven Asian subjects with CACG completed the study in the latanoprost-treated group. Most subjects were female (75%), and the mean age was 62.6±9.4 years. At baseline, the mean angle width was 0.84±0.55, and the mean number of clock hours of PAS was 4.67±2.95. After 12 weeks of treatment, latanoprost reduced IOP from 25.0±5.5 mmHg to 17.5±5.0 mmHg (P<0.001). The percent change in IOP produced by latanoprost was not associated with mean angle width (Spearman's r = 0.04, P = 0.64) or the number of clock hours of PAS (Spearman's r = −0.15, P = 0.08).
Conclusions
In subjects with CACG, the IOP-reducing efficacy of latanoprost was not affected by the degree of angle narrowing or extent of synechial angle closure.

Posted by mmiraftab at 11:16 AM | Comments (0)

Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes

Ophthalmology Volume 112, Issue 2 , February 2005, Pages 208-218

Design
Prospective, double-masked, randomized clinical trial.
Participants
Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
Results
Mean follow-up was 18 months (range, 12–36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4±0.48 and 0.5±0.53 (P = .03) in mitomycin C–treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C–treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
Conclusion
Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.

Posted by mmiraftab at 11:12 AM | Comments (0)

5-year follow-up of LASIK for hyperopia

Ophthalmology Volume 112, Issue 2 , February 2005, Pages 191-199

Results
At 5 years, for treatments between +1.00 to +3.00 D, 71.0% of eyes were within ±1.00 D of the intended correction, and for treatments between +3.5 to +6.0 D, 37.5% of eyes were within ±1.00 D of intended correction. From 12 to 54 months after surgery for all patients, there was a hyperopic shift of +0.53 D (range, −0.13 to +3.13 D), with 51.1% of eyes experiencing an increase of +0.50 D or more and 27.7% of eyes showing a hyperopic shift of more than +1.00 D. This hyperopic shift was +0.67 D (range, 0 to +1.125 D) for patients younger than 40 years of age and +0.44 D (range, −1.33 to +1.50 D) for patients between 43 and 55 years of age.
Conclusions
LASIK was moderately effective for the correction of low degrees of hyperopia. However, there was regression throughout the 5-year follow-up that was greater than would be expected as a result of aging. Long-term stability of hyperopic LASIK refractive corrections, therefore, is uncertain.

Posted by mmiraftab at 11:09 AM | Comments (0)

Treating Hyperopia Secondary to RK

CRST Jan 2005
In order of complexity, the therapeutic options for treating post-RK hyperopia are pilocarpine drops, the Grene encircling suture, PRK and variants thereof, LASIK, IntraLASIK, a phakic IOL, and refractive lens exchange.PRK and its variations are clearly the most predictable and safest option, as I will explain later. By contrast, LASIK risks corneal instability and irregular corneal astigmatism, and relifting the flap will produce “pizza-pie slices.” IntraLASIK presents the same challenges as LASIK in post-RK cases. The problem is not creating an excellent flap despite the presence of RK incisions, but rather it is the healing and relifting of the flap.To perform hyperopic PRK on a cornea with a history of RK, surgeons should first verify the astigmatic corneal meridia with a manual keratometer. Automated topography is notoriously inaccurate when reading a post-RK cornea, because the machine summates portions of the cornea instead of providing the most accurate astigmatic meridia over the visual axis. If the refraction and the manual keratometry are in agreement, disregard the information from the automated keratometer.Next, surgeons should remove the epithelium by any means desired, but they should not attempt to remove the epithelium within the depth of the RK incisions. Third, surgeons should reduce the goal of the surgery by 30%. For example, a +1.50D distance refraction with a goal of emmetropia should be treated as +1.00D.I still recommend constricting the pupil with 1% pilocarpine, because I believe that miosis allows for optimal centration of the ablation and offers even greater treatment accuracy than an eye tracker. No mitomycin C is necessary for treatments of less than +3.00D, but I recommend applying mitomycin C 0.02% for 2 minutes during all post-RK myopic PRK cases.

Posted by mehdi khanlari at 07:34 AM | Comments (0)

NONALCOHOL LASEK RETREATMENTS

CRST Jan 2005The technique that follows is mainly applicable to myopic LASEK retreatments; its efficacy in hyperopic retreatments cannot be guaranteed. The key to a successful myopic procedure lies in the correct realization of the Epi-Test without alcohol. If the test is negative (no folding of the epithelium is observed), diluted alcohol must be used
TechniqueI prepare an eye as per a LASEK procedure, and cut the epithelium with a trephine (rotated approximately 5° to both sides), and exert sufficient pressure to ensure a neat groove. Next, I dry the treatment surface area, while enhancing the visibility as much as possible. With the tip of a dry sponge, I perform an Epi-Test as previously described while covering the area limited by the groove. The folding of the epithelium must be clearly visible (Figure 1). With the help of a microhoe (Figure 2) or a bent needle, I confirm the cutting of the epithelium at the groove, beginning at the 6-o’clock position, and complete its separation until the hinge is reached. Normally, the flap will detach easily after this point (Figure 3), and, with the help of a spatula, I gather the flap at the 12-o’clock position. I keep the flap moist. After performing the laser ablation, I carefully reposition the epithelial flap and protect it with a contact lens.

Posted by mehdi khanlari at 07:28 AM | Comments (0)

FDA Clearance for First Cornea Laser Microscope

Review of ophthalmology Feb 2005
Heidelberg Engineering received Food and Drug Administration clearance for the Rostock Cornea Module, the key component for the company’s confocal laser microscope. The new product can image and measure corneal structures and diseases that were previously difficult, or even impossible, to see. The Heidelberg product is the first FDA cleared microscope using laser scanning technology for directly imaging a patient’s cornea. The new product displays magnified images of the internal structures of the cornea, enabling the clinician to directly view the cell layers and individual cells in real-time. This may prove especially important for recognizing parasitic infections which are affecting long term contact lens wearers in increasing numbers. The module connects directly to the HRT II, the company’s laser imaging instrument for glaucoma.

Posted by mehdi khanlari at 06:58 AM | Comments (0)

February 11, 2005

Results of the application of intraoperative mitomycin C in dacryocystorhinostomy

Eur J Ophthalmol 2004; 14: 461 - 463
To improve the success rate of DCR, the authors used MMC as an adjunct to surgery in 130 patients with nasolacrimal duct obstruction undergoing lacrimal surgery. They were assigned randomly into a MMC DCR group and a regular DCR group (control group).
Six patients in the mitomycin group were symptomatic after 6 months’ follow-up; probe and irrigation showed non-patency of lacrimal system. The success rate in the MMC group was therefore 90.5% (59/65), and in the conventional group it was 92.4% (60/65). No significant difference between the two groups was present (p=0.75).
CONCLUSIONS. The authors conclude that the use of intraoperative MMC in DCR surgery does not change the success rate of this procedure.

Posted by afarahi at 12:21 AM | Comments (0)

February 10, 2005

Intraorbital Surgery for Trigeminal Neuralgia.

Ophthalmic Plastic & Reconstructive Surgery. January,2005
First-division trigeminal neuralgia, or tic douloureux refractory to medications, presents problems to the surgeon because of the desirability of preserving corneal sensation. A new operation is described that may provide longer duration of pain relief than conventional supraorbital neurectomy, with preservation of the corneal reflex.Four patients underwent resection of the supratrochlear and supraorbital nerves within the orbit accessed from an upper eyelid skin crease incision.Three patients with typical idiopathic trigeminal neuralgia involving branches of the frontal nerve are without pain 22 to 25 months after surgery. The final patient with atypical pain had no improvement after the procedure. Frontal nerve distribution anesthesia is present in all patients. Postoperative ptosis resolved in all patients within 4 months of surgery.
Conclusions: This procedure should be added to the treatment options for patients with first-division trigeminal neuralgia. By avoiding injury to the trigeminal root and ganglion, this surgery carries no risk of facial motor dysfunction, dysthesia, and/or anesthesia in the other trigeminal branches including corneal anesthesia.

Posted by afarahi at 11:51 PM | Comments (0)

Retinal prosthesis development continues on positive path

Ophthalmology Times Jan 1, 2005

The prosthesis consists of an extraocular microelectronic device connected by an implanted multiwire cable to an epiretinal electrode array. Images are acquired by a small video camera worn externally on glasses and sent wirelessly to the extraocular microelectronic receiver and then via the cable to the epiretinal implant. The implant transmits electrical impulses to stimulate underlying healthy retinal neurons. Limited vision testing has also been conducted and has yielded promising findings as its results indicate the device has been able to restore some sight. Patients with the implants have been able to detect light, locate and count objects, and distinguish between common, simple objects in forced-choice tests,

Posted by mehdi khanlari at 06:34 PM | Comments (0)

What clinicians learned from OHTS, EMGT

Ophthalmology Times Jan 1, 2005
...."The function change was noted to be non-linear with respect to the pressure change," Dr. Heatley said. "This is evidence that every change of 1 mm Hg does matter, but not necessarily to the same degree across the range of pressure."Dr. Heatley suggested that perhaps there is a threshold pressure and above that pressure, the risk of retinal ganglion cell death is increased. If this is true, then the time in terms of hours or days above the threshold pressure would correlate with progression, he said. The time that the eye spent at or below the threshold would not "count" towards risk of cell death."If this model is true, then the work to be done is to find out the threshold pressure. Perhaps a multifocal or pattern ERG can be applied to find the threshold pressure, and methods of monitoring pressure more continuously may allow practitioners to calculate the number of IOP days above the threshold," he said. In this model, every "IOP day" would count, but not every mm Hg.

Posted by mehdi khanlari at 06:33 PM | Comments (0)

Stenting may help treat previously inoperable lesions

Ophthalmology TimesJan 1, 2005
A new approach to treating ocular ischemic syndrome—percutaneous carotid artery stenting—may be useful to treat previously inoperable lesions and provide subsequent visual and intracranial benefits, said Jeffrey L. Marx, MD.Common findings in ocular ischemic syndrome are rubeosis, peripheral retinal hemorrhages, and venous dilation without tortuosity. The syndrome is usually secondary to atherosclerotic coronary artery stenosis of greater than 90%, which results in a reduction of the ipsilateral perfusion pressure of about 50%The treatments available for ocular ischemic syndrome include panretinal photocoagulation for proliferative disease, carotid endarterectomy for lesions below the second cervical vertebra when stenosis is less than 100%, and angioplasty and stenting for lesions above the second cervical vertebra.To date, only one reported case of ocular ischemic syndrome has been treated with stenting for a lesion in the cervical carotid artery, but no cases of stenting to treat ocular ischemic syndrome in the intracranial circulation have been reported

Posted by mehdi khanlari at 06:11 PM | Comments (0)

February 09, 2005

Recent Premarket Approvals

OSN Jan 2005
¤ Bausch & Lomb has received FDA approval for an enhanced fitting guide for its Vision Shaping Treatment, a vision correction method that uses custom-fit gas permeable contact lenses worn overnight to temporarily reshape the cornea to correct nearsightedness and low amounts of astigmatism.
¤ CIBA Vision announced that its Aquify long-lasting comfort drops have received clearance from the FDA to add a specific indication for use to prevent and remove protein build-up on soft contact lenses.
¤ D.O.R.C. International received FDA approval for Vision Blue, a trypan blue ophthalmic solution for staining the anterior lens capsule during cataract surgery.
¤ Eyetech Pharmaceuticals and Pfizer Inc. received FDA approval for Macugen (pegaptanib sodium injection) for the treatment of wet age-related macular degeneration.
¤ The Food and Drug Administration granted marketing approval to Visx’s CustomVue laser vision correction procedure for the treatment of hyperopia and astigmatism.

Posted by mehdi khanlari at 07:58 AM | Comments (0)

Visual field ‘sum of slopes’ can predict VF progression

OSN Jan 2005
A visual field index called the sum of slopes can be used to estimate the probability of visual field worsening, according to a group of researchers.Kouros Nouri-Mahdavi and colleagues at the Jules Stein Eye Institute analyzed data from 161 participants in the Advanced Glaucoma Intervention Study to determine the probability of future glaucomatous visual field progression using clinical and perimetric data. Patients enrolled in the AGIS trial and chosen for this study had at least 8 years of follow-up and a baseline visual field score of less than 16. Visual field progression at 8 years was determined with point-wise linear regression (PLR) analysis.The course of VF progression over the first 4 years was quantified by an index, the sum of slopes, which was derived from the sum of all slopes of VF thresholds with P < 0.05 when PRL was performed on 4-year data.After 8 years, 64 eyes (40%) progressed as determined by PLR analysis. Two parameters emerged as predictive of subsequent visual field progression: a more negative sum of slopes (that is, a faster or more extensive deterioration), and older age at the 4-year mark. When the sum of slopes alone was used to predict outcomes, it had the same predictive power

Posted by mehdi khanlari at 07:54 AM | Comments (0)

Sclerothalamotomy ab interno a minimally invasive surgical option for glaucoma

OSN Feb 2005
Sclerothalamotomy ab interno is a surgical option for glaucoma that is as effective as trabeculectomy in lowering IOP but with fewer potential complications, according to Bojan Pajic“In all ab externo surgical techniques, penetrating and nonpenetrating, there is a possibility that fibroblasts from the conjunctiva migrate into the scleral tissue and proliferate there, blocking filtration. Sclerothalamotomy (STT), which is penetrating surgery with an ab interno, transcameral approach, prevents this risk and restores effective internal filtration through the internal episcleral and uveoscleral channels,”Similar to other surgical methods, STT ab interno circumvents the trabecular meshwork resistance by creating a drainage canal in the sclera, but the site of perforation is reached from the inside, and four sclerectomy sites are created using a special high-frequency diathermy probe. These sites are called “thalami,” from the Latin for “inner chamber,”

Posted by mehdi khanlari at 07:38 AM | Comments (0)

Manual LASEK without the use of alcohol can be performed in selected cases

OSN Feb 2005
PARIS – Laser epithelial keratomileusis can be performed manually but without the use of alcohol in selected cases,“The adherence of the epithelium to the stroma is extremely variable, and I found that there are quite a few eyes from which it can be detached easily with simple instruments. I test epithelial adherence at the beginning of the procedure, and if it is too tight, I use a mild 10% alcohol solution,” said Thierry Bour, MD.According to Dr. Bour, surgery begins with the surgeon marking the epithelium using a simple marker around the treatment area. The epithelial flap is cut along this line using a sharp microtip needle. With the same instrument, Dr. Bour tests the adherence of the epithelium along the edge.“By testing epithelial adherence we can select the cases in which the flap can be performed without using the alcohol. I start at the point where the epithelium is more loosely attached and lift the edge with a spatula. Then I penetrate under the flap with a larger spatula and progressively separate the epithelial flap from the stromal bed,” Dr. Bour explained.He noted that the epithelial flap obtained with this method is thinner and more delicate than LASEK flaps. Once lifted, it dries up quickly, and it should be moistened and protected with a drop of viscoelastic, he said.

Posted by mehdi khanlari at 07:07 AM | Comments (0)

February 08, 2005

LASEK innovator gives epi-LASIK high marks

OSN 2/8/2005

Epi-LASIK with the Centurion epikeratome from Norwood Eyecare is a beneficial innovation of laser epithelial keratomileusis, according to Massimo Camellin, MD, who developed the LASEK technique in 1999.At first I wasn’t sure that mechanical separation could be an advantage, especially in eyes with a strongly adherent epithelium,” said Dr. Camellin, here at the winter meeting of the European Society of Cataract and Refractive Surgeons. “Now that I have tried it, I must say that the mechanical device facilitates epithelial detachment in all eyes and makes surgery easier and more predictable also for beginner surgeons.Postoperative results in terms of patient comfort, recovery time and vision are comparable in the two techniques, but the epi-LASIK flap is easier to replace, smoother and more integral than the manually created LASEK flap, he added.I am going to introduce this innovation in my routine laser procedures,Dr. Camellin said, “although I think there is still some scope for alcohol separation in some cases. In patients with retinal problems, suction is better avoided, and also re-treatment with LASEK will continue to be performed with alcohol. The two techniques can be quite complementary.Dr. Camellin is currently finishing a study comparing the mechanical and alcohol separation techniques in 80 patients. Each patient will be treated with standard LASEK in one eye and epi-LASIK in the fellow eye.

Posted by mmiraftab at 07:58 PM | Comments (0)

Hyperopic Laser in situ Keratomileusis With 5.5-, 6.5-, and 7.0-mm Optical Zones

Journal of Refractive Surgery Vol. 21 No. 1 January/February 2005

PURPOSE
To evaluate the results of laser in situ keratomileusis (LASIK) for the correction of hyperopia and hyperopic astigmatism using a large 7.0-mm optical zone and to compare them with treatments using a 5.5- and 6.5-mm optical zone.
METHODS
One hundred sixty-one eyes of 89 patients with a mean preoperative spherical equivalent refraction of +2.44±1.32 diopters (D) (range: +0.00 to +5.62 D, cylinder 5.25 to 0.00 D) were treated for hyperopia and hyperopic astigmatism using a 7.0-mm optical zone and were analyzed retrospectively. Postoperatively, patients were examined after 1 day, 1 week, 1 month, 3 months, and 1 year. Eyes treated previously at the same center by the same surgeons with 5.5- and 6.5-mm optical zone applications were used as controls. All treatments were performed with the Nidek EC 5000 CXII excimer laser system (Nidek, Gamagori, Japan). A nasal hinged flap was created using the Nidek MK 2000 microkeratome in all cases.
RESULTS
The mean postoperative spherical equivalent refraction after 1 month (n=89) was +0.12±0.72 D (range: -1.75 to +2.75 D), +0.13±0.74 D (range: +1.88 to -1.62 D) at 3 months (n=70), and +0.20±0.69 D (range: -1.62 to +1.12 D) at 1 year (n=33). Regression between 1 month and 1 year was 0.08 D in the 7.0-mm optical zone group. Regression was 0.25 D in the 5.5-mm group and 0.02 D in the 6.5-mm optical zone group between 1 month and 1 year. In both the 5.5- and 6.5-mm optical zone groups, 13% of eyes lost one line in visual acuity (2% in the 7.0-mm optical zone group). The gain of one or more lines in visual acuity was 19% in the 5.5-mm group, 17% in the 6.5-mm group, and 27% in the 7.0-mm optical zone group. All data represent primary cases without retreatment.
CONCLUSIONS
Increasing the optical zone size from 5.5 mm to 6.5 mm and to 7.0 mm seems to improve refractive results, stability, and safety of hyperopic and hyperopic-astigmatic LASIK treatments. Although some hyperopic and astigmatic eyes are endangered by loss of lines in best spectacle-corrected visual acuity, more eyes gain one or more lines.

Posted by mmiraftab at 07:44 PM | Comments (0)

Simulation of Eye-tracker Latency, Spot Size, and Ablation Pulse Depth on the Correction of Higher Order Wavefront Aberrations With Scanning Spot Laser Systems

Journal of Refractive Surgery Vol. 21 No. 1 January/February 2005

PURPOSE
The aim of this theoretical work was to investigate the robustness of scanning spot laser treatments with different laser spot diameters and peak ablation depths in case of incomplete compensation of eye movements due to eye-tracker latency.
METHODS
Scanning spot corrections of 3rd to 5th Zernike order wavefront errors were numerically simulated. Measured eye-movement data were used to calculate the positioning error of each laser shot assuming eye-tracker latencies of 0, 5, 30, and 100 ms, and for the case of no eye tracking. The single spot ablation depth ranged from 0.25 to 1.0 µm and the spot diameter from 250 to 1000 µm. The quality of the ablation was rated by the postoperative surface variance and the Strehl intensity ratio, which was calculated after a low-pass filter was applied to simulate epithelial surface smoothing.
RESULTS
Treatments performed with nearly ideal eye tracking (latency ~ 0) provide the best results with a small laser spot (0.25 mm) and a small ablation depth (250 µm). However, combinations of a large spot diameter (1000 µm) and a small ablation depth per pulse (0.25 µm) yield the better results for latencies above a certain threshold to be determined specifically. Treatments performed with tracker latencies in the order of 100 ms yield similar results as treatments done completely without eye-movement compensation.
CONCLUSIONS
Reduction of spot diameter was shown to make the correction more susceptible to eye movement induced error. A smaller spot size is only beneficial when eye movement is neutralized with a tracking system with a latency <5 ms.

Posted by mmiraftab at 05:39 PM | Comments (0)

Hydrogel Plug to Fit Any Size, Shape

Review of ophthalmology,Feb,2005
Oasis Medical announces FDA approval of its new Form Fit long-term intracanalicular plug. The Form Fit plug is made of a hydrogel material that conforms to fit all patients with a single size. This material, upon contacting tear film, expands into a soft, pliable, gelatinous plug. It takes approximately 10 minutes to become completely hydrated and fill the vertical canalicular cavity.
There is no anchor or cap. It can be easily removed by flushing saline solution through the punctal opening. Form Fit comes preloaded on an inserter. The dry plug measures 3 mm in length and 0.3 mm in diameter and expands to 20 times the volume of its original size.

Posted by afarahi at 11:33 AM | Comments (0)

What’s new in ophthalmic surgery

Journal of the American College of Surgeons , January, 2005
Ophthalmic surgery, like all surgical disciplines, has evolved tremendously over the past 50 years. Technologies improve, and so do the procedures that implement them. Ophthalmology is a field that continues to look for improved methodologies to remove cataracts, to change refractive errors, to remove retinal pathologies, and to decrease intraocular pressure more efficiently. In this review, I will break down the various subspecialty areas and elucidate how they have changed over the past 12 months and talk briefly of the new frontiers that relate to them.Read more.....

Posted by afarahi at 11:14 AM | Comments (0)

February 07, 2005

A Genetic Contribution to Intraocular Pressure: The Beaver Dam Eye Study

Investigative Ophthalmology and Visual Science. 2005;46:555-560

PURPOSE. To investigate a potential genetic contribution to intraocular pressure (IOP), we performed a complex segregation analysis on 2337 individuals in 620 extended pedigrees ascertained through a population-based cohort, the Beaver Dam Eye Study (BDES). IOP is a principal risk factor for primary open-angle glaucoma (POAG) a leading cause of blindness worldwide.
METHODS. Segregation analysis is an analytical method that provides statistical evidence supporting the involvement of a major gene or polygenes in a particular phenotype. Detailed medical histories and eye examinations were performed on all participants. From the two eyes, the higher IOP measurement was used as a continuous trait after adjustment for covariates. A genome-wide scan (GWS) using affected sib pair linkage analysis was performed on 218 sibling pairs.
RESULTS. In this segregation analysis the model that allowed for an unmeasured major environmental effect plus a polygenic/multifactorial effect provided the best fit and was the most parsimonious model. The lack of an adequate fit for the Mendelian single-gene models is consistent with a multifactorial model of inheritance that may include multiple genes and environmental factors that contribute to IOP. The results of the GWS yielded two novel loci as potential linkage regions for IOP on chromosomes 6 (P = 0.008) and 13 (P = 0.0007). Neither of these regions has previously been identified in GWS of POAG.
CONCLUSIONS. The segregation and familial correlation analyses of IOP suggest a polygenetic component with environmental influences. The pilot linkage study further confirms the heterogeneity of IOP with the identification of two novel genetic loci.

Posted by mmiraftab at 09:50 PM | Comments (0)

Support for Polygenic Influences on Ocular Refractive Error

Investigative Ophthalmology and Visual Science. 2005;46:442-446

PURPOSE. Refractive errors, myopia, and hyperopia are common conditions requiring corrective lenses. The familial clustering of myopia has been well established. Several chromosomal regions have been linked to high myopia (12q, 17q, and 18q), to quantitative refraction among twins (3q, 4q, 8p, and 11p), and to families with moderate myopia (22q). This study examined the familial aggregation and pattern of inheritance of ocular refraction in an adult population, by using data from the Beaver Dam Eye Study.
METHODS. Familial correlations were examined and segregation analysis was performed on the average refractive error measurements in the right and left eyes after adjustment for age, sex, and education. Analyses were based on 2138 individuals in 620 extended pedigrees with complete data on age, sex, education, and spherical equivalent.
RESULTS. Substantial positive correlation was found between siblings (0.33), parents and offspring (0.17), and cousins (0.10) and lower correlation among avuncular pairs (0.08) after adjustment for age, sex, and years of education. The results of this segregation analysis do not support the involvement of a single major locus throughout the entire range of refractive error. However, models allowing for familial correlation, attributable in part to polygenic effects, provided a better fit to the observed data than models without a polygenic component, suggesting that several genes of modest effect may influence refractive error, possibly in conjunction with environmental factors.
CONCLUSIONS. These results support the involvement of genetic factors in the etiology of refractive error and are consistent with reports of linkage to multiple regions of the genome

Posted by mmiraftab at 09:38 PM | Comments (0)

Comparison of higher-order aberrations after LASEK with a 6.0 mm ablation zone and a 6.5 mm ablation zone with blend zone

JCRS MARCH 2004
Seoul, Korea,To compare the higher-order aberrations (HOAs) after laser-assisted subepithelial keratectomy (LASEK) using a conventional optical zone and a larger zone with a blend zone.
In this prospective study, 19 patients with a manifest refraction of −3.00 to −8.25 diopters (D) were treated with LASEK using a conventional (6.0 mm) optical zone in 1 eye and a larger (6.5 mm) zone with 8.0 mm blend zone in the other eye. The patients were followed for 3 months. Pupil size, best corrected visual acuity (BCVA), uncorrected visual acuity (UCVA), manifest refraction, corneal topography, pachymetry, and wavefront aberration were examined preoperatively; BCVA, UCVA, manifest refraction, and wavefront aberration were measured 1 and 3 months postoperatively. The Hartmann-Shack aberrometer (WaveScan®, Visx) was used to measure the overall wavefront aberrations in scotopic pupils.
Conclusions:In the scotopic condition, HOAs after LASEK using a large optical zone with blend zone ablation were smaller than those associated with conventional ablation zone treatment. The larger zone with blend zone treatment may be a good surgical alternative for better visual outcomes in scotopic conditions

Posted by alireza habibollahi at 03:36 PM | Comments (0)

Chronic dry eye and regression after myopic LASIK

JCRS MARCH 2004
Australia,This study was based on a retrospective analysis of a clinical database and a case study series. Data (N = 565 eyes) were collected before and after(2 weeks and 1, 3, 6, and 12 months) LASIK.
Conclusion:The risk for refractive regression after LASIK was increased in patients with chronic dry eye

Posted by alireza habibollahi at 03:29 PM | Comments (0)

Comparison of Nagahara phaco-chop and stop-and-chop phacoemulsification nucleotomy techniques

JCRS MARCH 2004
Seventy patients were evaluated prospectively in 2 groups. The Nagahara phaco-chop nucleotomy technique was performed in Group 1 (35 eyes) and the stop-and-chop technique in Group 2 (35 eyes). There were no significant between-group differences. The mean phaco time, phaco power, effective phaco time, time to achieve maximum vision, corneal thickness increase relative to the preoperative values, and time to return to the preoperative values were determined. All parameters in both groups were statistically compared using the chi-square test and the independent-samples t test.
Conclusions:
The Nagahara phaco-chop technique had fewer negative effects on the corneal endothelium as less ultrasonic energy was used. This accelerated the functional healing process and the return to preoperative physiologic values

Posted by alireza habibollahi at 03:21 PM | Comments (0)

Visual field changes after cataract extraction: The AGIS experience

American Journal of Ophthalmology
Volume 138, Issue 6 , December 2004, Pages 1022-1028

To test the hypothesis that cataract extraction in glaucomatous eyes improves overall sensitivity of visual function without affecting the size or depth of glaucomatous scotomas.

One hundred fifty-eight eyes (of 140 patients) from the Advanced Glaucoma Intervention Study with at least two reliable visual fields within a year both before and after cataract surgery were included. Average mean deviation (MD), pattern standard deviation (PSD), and corrected pattern standard deviation (CPSD) were compared before and after cataract extraction. To evaluate changes in scotoma size, the number of abnormal points (P < .05) on the pattern deviation plot was compared before and after surgery. We described an index (“scotoma depth index”) to investigate changes of scotoma depth after surgery.

Cataract extraction caused generalized improvement of the visual field, which was most marked in eyes with less advanced glaucomatous damage. Although the enlargement of scotomas was statistically significant, it was not clinically meaningful. No improvement of sensitivity was observed in the deepest part of the scotomas.

Posted by saliakbari at 09:54 AM | Comments (0)

Effect of optic material on posterior capsule opacification in intraocular lenses with sharp-edge optics
Department of Ophthalmology, Medical University of Vienna, Vienna, Austria
Received 5 May 2004; accepted 16 July 2004. Available online 25 November 2004

One hundred six eyes of 53 patients with age-related bilateral cataract enrolled in this study.
Each patient had cataract surgery in both eyes and received a silicone IOL in one eye and a hydrophobic acrylic IOL in the fellow eye. Follow-up examinations were at 1 and 3 years after surgery. Standardized high-resolution digital retroillumination images of the posterior capsule were taken. The amount of PCO was assessed subjectively at the slit lamp and objectively using automated image analysis software.
At 1 and 3 years after surgery, PCO did not differ between the silicone (1.6 and 1.9 [image analysis scores, 0–10 scale], respectively) and acrylic IOLs (1.7 and 2.2) (P > 0.24). Furthermore, there was no significant difference in best-corrected VA, rhexis/IOL overlap, capsular folds, and amount of anterior capsule opacification during the follow-up period. In each group, one neodymium:yttrium–aluminum–garnet (YAG) laser capsulotomy was performed during the entire study duration.
Conclusion
Silicone and hydrophobic acrylic are similarly effective in inducing the PCO-inhibiting effect of a rectangular, sharp optic edge. Three years after surgery, the PCO intensity and the YAG rate were low with both IOL models.

Posted by saliakbari at 09:34 AM |