Ophthalmology Review

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May 29, 2005

Evidence for the Oxygen/Cataract Connection

Am J of Ophthalmol 2005;139:302-310
A study by a group at Washington University School of Medicine in St. Louis is shedding new light on the role oxygen plays in cataract development.As reported in the American Journal of Ophthalmology, they measured oxygen concentrations in the eyes of patients undergoing retinal surgery. “It’s fairly well-accepted in the field that anyone over the age of 50 who has vitrectomy surgery will develop a cataract within two years,” Just before surgery, Dr. Holekamp measured oxygen levels adjacent to the lens and near the center of the eye in the vitreous gel of 69 eyes. Before retinal surgery, oxygen concentrations were very low in both places. After surgery, oxygen levels in both locations were about eight times higher than normal.“It seems one of the important functions of the vitreous gel is to keep oxygen away from the lens,” When we remove the gel, we remove that protective mechanism A co-investigator, David C. Beebe, PhD, believes the same kind of mechanism may contribute to cataracts that form as people age. The difference is that in age-related cataracts, the gel breaks down over several years. In vitrectomy patients, the gel disappears all at once.They believe that when the gel separates from the retina or begins to break down and liquefy, it allows fluid to flow over the surface of the oxygen-rich retina and carry that oxygen to the lens. That’s true whether the cause is vitreous liquefaction or the vitreous gel has been removed.The work suggested that some retinal diseases may protect patients from cataracts. For example, patients who had retinal surgery for complications of diabetes had significantly lower levels of oxygen near the lens. They plan a follow-up study of whether diabetic patients are somehow protected from cataracts.They also note that researchers in Japan have performed retinal surgery without removing the vitreous gel. The surgery is more difficult to do, but the Japanese team found that when the vitreous gel remains intact, retinal surgery patients don’t develop nuclear cataracts to the same extent. Dr. Holekamp isn’t proposing that retinal surgeons stop doing vitrectomies, but she says lowering oxygen concentrations in the fluid that replaces the vitreous gel might help protect the lens. She and her colleagues plan to investigate methods to do so.....“Perhaps we could replace the vitreous gel with a gel polymer that would keep oxygen away from the lens,” he says. “Now that we’re beginning to get an idea of how the vitreous gel works, it may be possible to design interventions to protect the lens both in people who have had a vitrectomy and in those whose vitreous is degenerating as a part of normal aging.”

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Posted by mehdi khanlari at 11:58 PM | Comments (0)

Two Innovations Aid Post-Refractive Surgery

Review of Ophthalmology May 2005
Quantel Medical has introduced new Axis II PR, the latest offering in the company’s Precision A-Scan product line, addresses the preop cataract surgery biometry challenge posed by post-refractive surgery patients by providing six additional post-refractive formulas with clinical efficacy that’s equivalent to laser interferometry. The system also features IOL powers in 0.25-D increments. The company says that the Axis II PR includes formulas to meet the surgeon’s biometry needs whether or not the patient’s preoperative keratometry or refraction history is available.

Posted by mehdi khanlari at 11:40 PM | Comments (0)

Nystagmus can be the presenting sign of multiple sclerosis

Ophthalmology Times May 1, 2005
Multiple sclerosis (MS) can present to the ophthalmologist with visual loss (e.g., opticneuritis), diplopia (e.g., internuclear ophthalmoplegia [INO] or sixth-nerve palsy), or nystagmus.An INO is characterized by an ipsilateral adduction deficit and a contralateral abducting dissociated horizontal nystagmus on horizontal gaze. In a young patient, a new INO should be considered to represent MS until proven otherwise. The lesion involves the medial longitudinal fasciculus (MLF), the interneuron between the sixth- and third-nerve nuclei. Careful attention to the horizontal saccades might bring out a subtle INO.Jerk beating nystagmus is named for the fast phase (e.g., fast phase down = beating nystagmus). Downbeat nystagmus typically worsens in downgaze and lateral gaze and localizes to the cervicomedullary junction. Upbeat nystagmus localizes to the pontomedullary junction or in some cases the cerebellar vermis. Periodic alternating nystagmus (PAN) demonstrates a horizontal fast phase in one direction, followed by a slowing of the nystagmus, a null phase with minimal or no eye movement, and then the nystagmus alternates with the fast phase toward the opposite direction. Acquired pendular nystagmus has an equal amplitude and frequency in both directions and is a relatively common finding in MS Any acquired nystagmus in an adult should prompt a cranial MRI with contrast enhancement aimed at the clinical localization Ophthalmologists should be aware that nystagmus can be the presenting or only sign of MS. The abducting nystagmus of the INO and acquired pendular nystagmus are common nystagmus presentations.

Posted by mehdi khanlari at 11:32 PM | Comments (0)

Biomarkers of cardiovascular disease are possible risk factors for AMD

Ophthalmology Times May 1, 2005
...The results showed the CRP and homocysteine levels were elevated in the group with AMD when compared with the unaffected controls. The mean CRP level was 3.42 mg/l in the AMD group and 2.30 mg/l in the controls (p = 0.03). The mean homocysteine level was 11.72 µmole/l in the AMD patients and 8.88 µmole/l in the unaffected patients (p < 0.0001)."Our study supports the role of low-grade chronic inflammation in AMD. Low-grade chronic inflammation plays a pivotal role in atherosclerosis," .Elevated homocysteine in individuals with AMD supports the cardiovascular role in the pathogenesis of AMD. It remains unclear whether homocysteine is causative of atherosclerosis, or a marker of existing vascular disease," .

Posted by mehdi khanlari at 10:56 PM | Comments (0)

Preliminary Efficacy and Safety of Zero Diopter Lens Implantation in Highly Myopic Eyes

American Journal of Ophthalmology May 2005
Three highly myopic eyes with axial lengths greater than 30 mm were implanted with zero D Alcon model MA60MA 3-piece acrylic posterior chamber lenses at the time of cataract surgery.Uncorrected visual acuity improved from counting fingers to 20/20− and 20/40− in two eyes. Best-corrected visual acuity improved from 20/80 and 20/60+ to 20/20− in the same eyes. A third eye was at counting fingers before and after surgery, because of a staphyloma. The range of preoperative, intended postoperative, and achieved postoperative spherical equivalent refractive errors was −15.1 to −25.0 diopters, −0.20 to −1.44 diopters, and +0.13 to +0.50 diopters respectively.ConclusionsAll eyes experienced mild hyperopic refractive errors after surgery. No retinal detachments occurred during the follow-up interval.

Posted by mehdi khanlari at 10:52 PM | Comments (0)

The impact of cataract severity on measurement acquisition with the IOLMaster

Acta Ophthalmologica Scandinavica June 2005
Conclusions: The IOLMaster fails to acquire axial length measurement in approximately 20% of UK public hospital cataract patients. Failure is principally due to PSC, whereby the LOCS III score of p = 3.5 defines the limit of PSC severity that the IOLMaster can measure.

Posted by mehdi khanlari at 10:41 PM | Comments (0)

Green laser pointers can cause visible retinopathy

Archives of Ophthalmology, May 2005
The eye of a patient due for enucleation was exposed to the laser at different periods of time – 60 seconds, five minutes and 15 minutes. Exposure as short as 60 seconds discolored the retina. The authors conclude that green lasers are more damaging to the eyes than red lasers.

Posted by kjalali at 07:50 PM | Comments (0)

Balloon dilatation for congenital nasolacrimal duct obstruction appears safe, effective in children older than 3 yr

European Journal of Ophthalmology, May 2005
Initially, this procedure was successful 83.3 percent of time. After a second procedure, the success rate jumped to 87.5 percent. The authors suggest this treatment can be used as an alternative in older children and can be preferred to silicone intubation and dacryocystorhinostomy performed after unsuccessful probing.

Posted by kjalali at 07:47 PM | Comments (0)

Goldmann applanation tonometer calibration should be checked before each use

Journal of Glaucoma, June 2005
A prospective check of this tonometer revealed that it’s not as accurate as the manufacturer's recommended calibration error tolerance of +/-0.5 mm Hg would suggest. The authors suggest calibration error checks be carried out at least once monthly and, ideally, before each session. Additional checks should be made if tonometers suffer specific damage. Tonometers with a calibration error greater than +/-2.5 mm Hg should be returned to the manufacturer for re-calibration.

Posted by kjalali at 07:45 PM | Comments (0)

Novel index for predicting IOP reduction following cataract surgery

British Journal of Ophthalmology, May 2005
IOP reduction following cataract surgery was found to be positively related to preoperative IOP, and inversely related to preoperative anterior chamber depth. As a result, the authors suggest a novel index – the pressure to depth ratio – is strongly predictive for IOP reduction following cataract extraction and may prove useful in surgical decision making.

Posted by kjalali at 07:40 PM | Comments (0)

May 28, 2005

Selective Upregulation of the A3 Adenosine Receptor in Eyes with Pseudoexfoliation Syndrome and Glaucoma

(Investigative Ophthalmology and Visual Science. 2005;46:2023-2034.)
Adenosine is increasingly released in metabolic stress conditions, like hypoxia or ischemia, and regulates many physiologic processes, such as aqueous humor secretion and intraocular pressure, via activation of four adenosine receptors. In the current study, the role of the adenosine system in the pathophysiology of pseudoexfoliation (PEX) syndrome, which is typically associated with anterior chamber hypoxia and elevated intraocular pressure, was examined.All four adenosine receptor subtypes (A2A > A1 > A2B > A3) were coexpressed but differently distributed in the ciliary epithelium of control eyes, with the A3 receptor being localized to the basolateral membrane infoldings of the nonpigmented epithelial cells. A selective, approximately 10-fold upregulation of A3 receptor mRNA and protein was consistently found in the nonpigmented ciliary epithelium of all PEX eyes, with and without glaucoma, compared with the normal and glaucomatous control eyes. Significant upregulation of A3 receptor message in nonpigmented epithelial cells was induced by both hypoxia and oxidative stress in vitro, together with increased levels of inosine, hypoxanthine, and xanthine in the supernatants. Levels of adenosine and its catabolites, however, were not significantly elevated in the aqueous humor of patients with PEXCONCLUSIONS. Considering the known role of the A3 adenosine receptor in modulating aqueous humor secretion, its selective, probably hypoxia-induced upregulation in the ciliary epithelium may not only confer cytoprotection but also influence aqueous humor dynamics and may be accessible to therapeutic intervention in patients with PEX.

Posted by mehdi khanlari at 11:49 PM | Comments (0)

Intracorneal Hydrogel Lenses and Corneal Aberrations

JOURNAL OF REFRACTIVE SURGERY Vol. 21 No. 3 May/June 2005
A retrospective, nonconsecutive, observational study of the anterior corneal surface aberration profile of four hyperopic eyes previously implanted with an intracorneal hydrogel lens were studied by videokeratographic elevation maps before and 6 months after surgery.Intracorneal hydrogel lenses reduced the optical performance in all four eyes by increasing the spherical aberrations by a mean factor of 1.87 and 1.95, coma aberrations by a mean factor of 2.98 and 3.01, and total higher order aberrations by a mean factor of 2.6 and 2.17 at 3.0-mm and 6.5-mm pupils, respectively (P<.005 CONCLUSIONS Intracorneal hydrogel lenses decreased the optical performance of the cornea by significantly increasing spherical, coma, and total higher order aberrations. [J Refract Surg. 2005;21:247-252.]

Posted by mehdi khanlari at 11:43 PM | Comments (0)

Automated Lamellar Keratoplasty for Recurrent Granular Corneal Dystrophy After Phototherapeutic Keratectomy

JOURNAL OF REFRACTIVE SURGERY Vol. 21 No. 3 May/June 2005
We performed a prospective interventional noncomparative case study of nine eyes (seven patients) with severe recurrent granular corneal dystrophy after PTK. An automated microkeratome was used to cut partial-thickness sections through the anterior surface of the donor and host corneas. The donor disc was placed on the recipient bed with four or eight interrupted sutures. The sutures were removed between 4 and 6 weeks postoperatively. During a mean follow-up period of 18.9±4.1 months, all grafts were transparent without visible opacity at the interface, and no serious complications occurred. In all cases, the visual acuity improved: seven eyes had best spectacle-corrected visual acuity of ≥20/40; two eyes reached 20/25. At last follow-up >12 months postoperatively, the mean corneal refractive power had significantly increased by 2.34±0.93 diopters (D) (P<.001), and the corneal astigmatism significantly decreased by 0.91±0.98 D (P<.05). The mean corneal thickness was 477.4±26.9 µm preoperatively and 507.8±23.4 µm at last follow-up (P<.001). CONCLUSIONSOur findings suggest that automated lamellar keratoplasty for the treatment of recurrent granular corneal dystrophy is a safe and effective method of improving visual acuity, but recurrence remains a risk. [J Refract Surg. 2005;21:288-293.]

Posted by mehdi khanlari at 11:41 PM | Comments (0)

Prolonged Antiscarring Effects of Ilomastat and MMC after Experimental Glaucoma Filtration Surgery

Investigative Ophthalmology and Visual Science. 2005;46:2018-2022

In a randomized, prospective, masked-observer study, 21 New Zealand White rabbits underwent modified GFS. The animals were allocated to receive either intraoperative mitomycin-C (MMC) at a concentration of 0.2 mg/mL or postoperative subconjunctival injections of either ilomastat or phosphate-buffered saline (PBS).RESULTS. Ilomastat significantly improved surgical outcome compared with vehicle (P < 0.0163) and length of bleb survival was similar to the MMC group. The mean day of failure was 46.2 (range, 42–60) with ilomastat, 51.3 (range, 49–60) with MMC, and 16 (range, 15–21) with vehicle. IOP maintenance with ilomastat was similar to that in the MMC group. Histologically, minimal scar tissue was seen with MMC and ilomastat. MMC-treated tissue demonstrated subconjunctival hypocellularity associated with peripheral fibrosis. Ilomastat resulted in normal-appearing conjunctival morphology.CONCLUSIONS. Ilomastat successfully prolongs bleb survival. MMP inhibition may provide an additional, potentially safer method of controlling intraocular pressure, thus preventing failure of glaucoma surgery, and may also act as a potential adjuvant treatment when MMC alone is inadequate.

Posted by mehdi khanlari at 11:31 PM | Comments (0)

May 27, 2005

Comparison of Mydriatic Regimens Used in Screening for Retinopathy of Prematurity in Preterm Infants With Dark Irides

Journal of Pediatric Ophthalmology and Strabismus,May/June, 2005
This cross-sectional, randomized, double-masked clinical trial compared cyclopentolate 1% + phenylephrine 2.5%, tropicamide 1% + phenylephrine 2.5%, and a prepared combination of cyclopentolate 0.2% with phenylephrine 1% for pupillary dilation in preterm infants with dark irides. Thirteen infants were randomized to each regimen. All three mydriatic regimens provided adequate pupillary dilation at 45 minutes, with dilation sustained at 60 minutes. There was a significant increase in mean blood pressure in the cyclopentolate 1% + phenylephrine 2.5% and the tropicamide 1% + phenylephrine 2.5% groups. Although there was no significant change of abdominal girth in any of the three groups, a total of eight patients developed intolerance to feeds; four (50%) of these infants were from the cyclopentolate 1% + phenylephrine 2.5% group.
CONCLUSION:The prepared combination of cyclopentolate 0.2% + phenylephrine 1% appears to be the mydriatic of choice for preterm infants with dark irides as it provided adequate pupillary dilation with the least systemic side effects.

Posted by afarahi at 08:54 PM | Comments (0)

Three-Muscle Surgery for Infantile Esotropia in Children Younger Than Age 2 Years

Journal of Pediatric Ophthalmology and Strabismus,May/June, 2005
Surgical records of 10 patients with esotropia ≥ 55 prism diopters (PD) who underwent three-muscle surgery for large-angle infantile esotropia were reviewed.Mean age at initial surgery was 13 months. Mean preoperative deviation was 62.5 PD of esotropia. A single surgery was associated with satisfactory horizontal alignment in only three (30%) patients at last follow-up (mean, 37.1 months; range, 8-70 months). Esotropia was undercorrected in one (10%) and overcorrected in six (60%) patients, all of whom required additional surgery. One patient with satisfactory horizontal alignment required an additional procedure to correct a right hypertropia causing a left face turn.
CONCLUSIONS:In contrast to older children and adults, three-muscle surgery may be inappropriate for infants with large-angle esotropia due to a large overcorrection rate. This controversy may benefit from a prospective study.

Posted by afarahi at 08:31 PM | Comments (0)

Corneal Tattooing for the Treatment of Debilitating Glare in a Child With Traumatic Iris Loss

AJO,May,2005
A six-year-old girl underwent corneal tattooing (platinum chloride reduced by hydrazine) in the relevant scarred corneal sector.
Six months after the procedure, the child enjoyed a more normal corneal appearance and no longer suffered from glare. Postoperative epithelial healing, however, was slow and required vigilance.
Conclusions:Corneal tattooing can allow both cosmetic and therapeutic benefit when indicated in a child. However, postoperative healing may require management when using platinum chloride reduced by hydrazine.

Posted by afarahi at 08:23 PM | Comments (0)

May 26, 2005

Comparison of PCO rates between hydrophilic and hydrophobic single-piece acrylic intraocular lenses

JCRS APRIL 2005
United Kingdom.One hundred six eyes of 53 patients with bilateral cataract and no other ocular comorbidity were prospectively randomized to receive a hydrophobic acrylic or hydrophilic acrylic single-piece IOL in the first eye to have surgery. The alternate IOL was implanted in the fellow eye 4 to 6 weeks later. All surgery was performed by a single surgeon. Postoperative follow-up was 1 day, 1 and 6 months, and 1 year. At each visit, the best corrected high- and low-contrast visual acuities were assessed and a high-intensity digital retroillumination photograph was taken. Posterior capsule opacification was assessed from the digital images by a single operator using a dedicated software program and calculated as the percentage area of opacified capsule.
Conclusions
The rate of PCO was significantly higher with the hydrophilic IOL. However, the results cannot be attributed to the IOL material alone as they show the importance of both IOL material and design.

Posted by alireza habibollahi at 07:59 AM | Comments (0)

JCRS APRIL 2005
BCVA and photopic and mesopic contrast sensitivity in pseudophakic patients implanted either with the aspheric intraocular lens (IOL) designed to correct for corneal spherical aberration or with a conventional IOL.
Methods
Thirty eyes of 30 patients after aspheric lens implantation (Pfizer/Pharmacia Tecnis Z9000) were compared with 30 eyes of 30 age-matched patients after conventional lens implantation (Alcon AcrySof SA60AT). Two to three months after surgery, BCVAF was measured Contrast sensitivity was measured by sinusoidal grating charts for distance at photopic (85 cd/m2) and mesopic (6 cd/m2) luminance level with optical correction in place. Tested spatial frequencies were 1.5, 3, 6, 12, and 18 cycles per degree (cpd).
Conclusions
The aspheric Tecnis IOL yielded better BCVA and better distance contrast sensitivity than the conventional IOL. The differences were clinically significant for higher spatial frequencies. The results give some suggestions for further studies.

Posted by alireza habibollahi at 07:53 AM | Comments (0)

Assessment of central corneal thickness using optica ltomography coherence

JCRS APRIL 2005Purpose
To demonstrate the capability of model OCT3 evaluate CCT in normal human corneas in vivo and compare the results with the those of standard ultrasound (US) pachymetry and Orbscan
The CCT in 22 eyes of 11 subjects was determined with the OCT3 (Carl Zeiss Meditec), Orbscan (Bausch & Lomb, Inc.), and US pachymetry (DGH Technology, Inc.). Three central corneal scans of each eye were obtained using the OCT3. First, OCT3 data were processed using the standard OCT software program (OCT3std). Second, OCT3 raw data were exported and measurements were repeated using Scion Image for Windows program (OCT3sci). The OCT3 and Orbscan results were compared with the mean of 5 US pachymetry measurements in each eye.
Conclusion
Results show the OCT3 is an accurate, noninvasive, and reproducible technique for evaluation of CCT.

Posted by alireza habibollahi at 07:46 AM | Comments (0)

Pachymetric evaluation prior to laser in situ keratomileusis

JCRS Volume 31, Issue 4, Pages 701-706 (April 2005)
To determine whether deviations in the localization of the cornea's thinnest point or the magnitude and localization of posterior corneal ectasia is associated with deviations in the spherical equivalent, the astigmatism, or the magnitude of an anterior corneal ectasia and whether corneas at risk for iatrogenic keratectasia can be identified without a pachymetry map of the cornea.
volunteers with various refractive errors were examined with Orbscan II and The corneal thickness was registered at the fixation point, at the geometrical center, and at the thinnest point of the cornea.
Results
The thinnest point of the cornea was predominantly located in the inferotemporal quadrant, and was significantly thinner than the fixation point (539.6 ± 35.8 μm and 548.0 ± 35.4 μm, respectively, P<.001). Conclusions
The absence of a clear relationship between the shape of the anterior corneal surface or the refractive error, and the shape of the posterior corneal surface, necessitates a thorough pachymetric evaluation of the cornea before LASIK,with special attention to the inferotemporal area.

Posted by alireza habibollahi at 07:37 AM | Comments (0)

May 25, 2005

Superior Oblique Muscle Involvement in Thyroid Ophthalmopathy

Journal of AAPOS,April,2005
Rectus muscle involvement in thyroid ophthalmopathy is well documented. The inferior rectus is the most frequently involved, followed by the medial, superior, and infrequently the lateral rectus. This study reports involvement of the superior oblique muscle as a contributory cause of restrictive strabismus in patients with thyroid ophthalmopathy. This is a retrospective review of four patients with known thyroid ophthalmopathy who presented with incomitant vertical strabismus, A-pattern, overdepression in adduction, underelevation in adduction, and incyclotorsion. All patients underwent preoperative orbital imaging. Two of the four patients had previous orbital decompressions. All patients underwent surgery on the SO muscle. Preoperative scans showed enlargement of one or both SO muscles in all patients and intraoperative forced duction testing revealed restriction to elevation in adduction in all cases. Preoperative A-pattern ranged from to 6 to 22 prism diopters. All subjects had preoperative incyclotorsion, ranging from 2 and 14 degrees. Improvement of the versions, hypertropia, and cyclotorsion followed surgical weakening procedures on the SO muscle.
Conclusion: Thyroid ophthalmopathy may involve the SO muscle. Clinical manifestations include preoperative A-pattern strabismus, incyclotorsion, and restrictive limitation to elevation in adduction. Orbital imaging documents SO muscle enlargement. Awareness of SO involvement in thyroid ophthalmopathy assists the surgeon to develop a more precise surgical strategy to correct the hypotropia.

Posted by afarahi at 12:51 AM | Comments (0)

A Randomized Pilot Study of Near Activities Versus Non-Near Activities During Patching Therapy for Amblyopia

Journal of AAPOS,April,2005
The Pediatric Eye Disease Investigator Group*

Sixty-four children, 3 to less than 7 years of age, with anisometropic, strabismic, or combined amblyopia (20/40 to 20/400) were randomly assigned to receive either 2 hours of daily patching with near activities or 2 hours of daily patching without near activities. After 4 weeks of treatment, there was a suggestion of greater improvement in amblyopic eye visual acuity in those assigned to near visual activities (mean 2.6 lines versus 1.6 lines, P = 0.07). The treatment group difference in visual acuity was present for patients with severe amblyopia but not moderate amblyopia. Conclusions: The results suggest that performing near activities while patched may be beneficial in treating amblyopia.

Posted by afarahi at 12:04 AM | Comments (0)

May 23, 2005

Workup Guidelines for Managing Normal- Tension Glaucoma

Review of Ophthalmology

To help determine whether a patient has normal-tension glaucoma or a different physical or neurological problem, I recommend the following:

• Check the visual field. Normal-tension glaucoma often has a characteristic dense paracentral loss impinging on fixation (superiorly more than inferiorly).
• Examine stereo disc photos, and/or HRT/GDx scans. Eyes with the same amount of total visual field loss as a POAG patient will have a thinner neuroretinal rim, especially superiorly and inferiorly. They are also more likely to have peripapillary atrophy.
• Check corneal pachymetry. Rule out an IOP error caused by a thin cornea.
• Perform gonioscopy. This can rule out subacute angle closure.
• Review the big picture. Go over the history of any present illnesses and conduct a Review of Systems. Consider having an autoimmune workup done if the Review of Systems is positive.
• Have an internist perform a comprehensive physical examination. The focus should be on neurological and circulatory concerns.
• Consider other tests. These could include an electrocardiogram, a complete blood count, and a serologic test for syphilis.
• If appropriate, order 24-hour blood-pressure monitoring. This may reveal blood-pressure related problems.
• If appropriate, perform neuroimaging. This is useful if the Review of Systems is positive, or the disc and/or visual field are not characteristic of glaucoma. Cupping occurs with neurologic disease at the following rates: arteritic ischemic optic neuropathy—50 percent; non-arteritic ischemic optic neuropathy—10 percent; compressive lesions—5 percent; and optic neuritis—less than 5 percent.

Some general guidelines: 1) With early loss of color vision or central vision, or if a visual field defect obeys the midline, odds are good that the problem is neurologic. 2) Remember that glaucoma is a chronic disease—be suspicious of rapid visual acuity loss. 3) When the problem is neurologic, both vision and pallor tend to be worse than the cupping. Conversely, when the problem is glaucoma, the cupping tends to be worse than the vision problems or pallor. 4) Generally, if the problem is glaucoma, you should be able to predict the visual field results by looking at the disc.
Finally, if it’s clear that your patient really does have NTG, aim to reduce pressure by 40 percent, with surgery as a viable option.

Posted by mehdi khanlari at 11:32 PM | Comments (0)

Measuring CCT? Plan to Do It Again

Ophthalmology 2005; 112:225-228
Researchers at London’s Moorfields Eye Hospital recruited 51 patients from a glaucoma clinic and measured central corneal thickness using an ultrasonic handheld pachymeter by a trained observer three consecutive times over a three-month period. The readings showed clear fluctuation over the period, with a mean difference in CCT of 9.6 ±26.9 µm in the right eye and 19.0 ±29.2 µm in the left. In addition, there was a systematic bias towards increased CCT being recorded at the second reading in both eyes, reaching statistical significance in both the right eye (P=0.02) and the left (P=0.0003). The criteria used to categorize the risk of developing glaucoma in the OHTS were then applied to these results. On the basis of the second reading, 32 percent of eyes required recategorization in both the right and left eyes.They conclude that CCT measurements taken within a clinical setting by a trained observer may show significant variability. Failure to do more than one CCT reading may result in misclassification and, thus, an inaccurate assignment of risk.

Posted by mehdi khanlari at 11:23 PM | Comments (0)

Globe rupture following penetrating keratoplasty. How often, why, what can we do to prevent it?

American Journal of Ophthalmology May 2005, Page 958
This was a case-controlled study to compare the postsurgical rates of globe rupture after penetrating keratoplasty (PKP), phacoemulsification (PCE), and extracapsular cataract surgery (ECCE). The incidence of globe rupture after PKP (5.8%) was statistically significant higher than PCE (0%, P < .0001) and ECCE (0.45%, P = .005). The original indication for PKP did not influence the rupture rate. The period of greatest risk was during the first postoperative month, during which time 37.5% of all cases occurred, and during the first month after suture removal. Fifty percent of ruptured globes after PKP had a final visual outcome of hand movement or worse. Eyes with PKP have a lifetime increased risk of globe rupture.

Posted by mehdi khanlari at 11:18 PM | Comments (0)

Choosing the Location of Corneal Incision Based on Preexisting Astigmatism in Phacoemulsification

American Journal of Ophthalmology May 2005

A total of 574 patients in five stages were assigned to the following incisions: superior or temporal (n = 89), superior (n = 141), superior or superior plus relaxing (n = 102), nasal or temporal (n = 156), and incisions based on applying conclusions of preceding and current studies (n = 86). Visual acuity, refraction, biomicroscopy, keratometry, and videokeratography (Fourier analysis) were performed before and after phacoemulsification and intraocular lens implantation (3.5-mm incision). main outcome measures: Corneal refractive and surface regularity index change between preoperative and 6-month postoperative examination. Visual acuity at 6 months.ResultsIn patients without corneal astigmatism, corneal changes induced were greater in superior than temporal incision. After a superior incision (preoperative steep axis at 90 degrees), a shift of the axis 90 degrees away was less likely with at least 1.5 diopters of astigmatism. A perpendicular relaxing limbal incision decreased corneal changes. Nasal incision induced greater corneal change than temporal incision (preoperative steep axis at 180 degrees). A shift of this axis 90 degrees away was more likely with astigmatism < 0.75 diopters in temporal incision and < 1.25 diopters in nasal incision.ConclusionsSuperior incision is recommended with at least 1.5 diopters of astigmatism and steep axis at 90 degrees. Temporal incision is recommended with astigmatism < 1.5 diopters and steep axis at 90 degrees, negligible astigmatism, or astigmatism < 0.75 diopters and steep axis at 180 degrees. Nasal incision is recommended with at least 0.75 diopters of astigmatism and steep axis at 180 degrees.

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

Effect of cataract surgery incision location and intraocular lens type on ocular aberrations

JCRS April 2005
This study comprised 74 subjects; 17 were phakic with no ocular pathology, 20 had implantation of a Pharmacia 722C PMMA IOL through a scleral tunnel, 21 had implantation of an Alcon AcrySof IOL through a scleral tunnel, and 16 had implantation of an AcrySof IOL through a corneal incision. Visual acuity and contrast sensitivity testing, ocular optical quality measurement using Hartmann-Shack wavefront sensing, and corneal surface measurement with a videokeratoscope were performed in all cases.ResultsThere were significant differences between groups in the total root-mean-square (RMS) wavefront aberration over a 6.0 mm pupil (F = 3.91; degrees of freedom = 3,70; P<.05) mediated at the 4th-order RMS, specifically spherical and tetrafoil aberrations. The PMMA–scleral group had the least aberrations and the AcrySof-corneal group the most. For a 3.5 mm diameter pupil, the total higher-order RMS wavefront aberration was not significantly different between the groups (P>.05). There were no differences between groups in corneal shape, visual acuity, or contrast sensitivity.ConclusionsImplantation of the spherical PMMA IOL led to a slight reduction in total wavefront aberration compared to phakic eyes. AcrySof IOLs induced more aberrations, especially spherical aberration. Corneal-based incisions for IOL implantation compounded this increase. Studies of the optical performance of IOLs in vivo should use wavefront sensing as the main outcome measure rather than visual measures, which are readily confounded by multiple factors.

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

May 22, 2005

Pigment dispersion and Artisan phakic intraocular lenses: Crystalline lens rise as a safety criterion

JCRS April 2005

A comparative analysis of crystalline lens rise in 9 eyes with pigment dispersion and 78 eyes without dispersion was performed. All eyes had previous implantation of an Artisan IOL. Anterior segment imaging was done using an anterior chamber optical coherence tomography (AC OCT) prototype. Crystalline lens rise was defined by the distance between the anterior pole of the crystalline lens and the horizontal plane joining the opposite iridocorneal recesses.ResultsThe study confirmed that crystalline lens rise can be considered a safety criterion for implantation of Artisan-type phakic IOLs. The higher the crystalline lens rise, the greater the risk for developing pigment dispersion in the area of the pupil. This complication occurred more frequently in hyperopic eyes than in myopic eyes. Results indicate there is little or no risk for pigment dispersion if the rise is less than 600 μm; 67% of eyes with a rise of 600 μm or more developed pupillary pigment dispersion. In some cases in which the IOL was loosely fixated, there was no traction on the iris root and dispersion was prevented or delayed.Conclusions Crystalline lens rise should be considered a new safety criterion for Artisan phakic IOL implantation and should also be applied to other types of phakic IOLs. The distance remaining between the crystalline lens rise and a 600 μm theoretical safety level allows one to calculate how long the IOL can safely remain in the eye.

Posted by mehdi khanlari at 11:28 PM | Comments (0)

Cohort study of 27 cases of endophthalmitis at a single institution

JCRS April 2005
This retrospective cohort study consisted of patients who had surgery for cataract(s) at this eye hospital. A 10% sampling of all patients operated on for cataract surgery from January 1, 1996, to December 31, 2002, were compared with all cases of postcataract surgery bacterial endophthalmitis during this same time period at this institution. The main outcome measure(s) included surgical complication, first postoperative day wound leak, incision placement and location, intraocular lens material, whether a suture was placed, antibiotic used, collagen shield use, and whether the eye was patched.
Results A total of 1525 patients were in the control cohort, and there were 27 cases of endophthalmitis. In a multivariate regression analysis, the factors found to be statistically associated with endophthalmitis were (1) wound leak on the first postoperative day (odds ratio [OR] 44 ± 42; confidence interval [CI] 6.85 to 287; P<.001); (2) capsular or zonular surgical complication (OR 17.2 ± 14.2; CI 3.44 to 86.4; P = .001); (3) topical antibiotic started the day after surgery rather than the day of surgery (OR 13.7 ± 12.9; CI 2.17 to 90.9; P = .005); (4) use of ciprofloxacin rather than ofloxacin topically after surgery (OR 5.3 ± 3.6; CI 1.41 to 20.0; P = .014); (5) not patching after surgery (OR 7.1 ± 5.6; CI 1.47 to 36.4; P = .015); and (6) not placing a collagen shield soaked in antibiotic (OR 2.7 ± 1.3; CI 1.06 to 7.14 P = .037).ConclusionIn sutureless cataract surgery, surgical complications and wound leak on the first postoperative day were most strongly associated with endophthalmitis.

Posted by mehdi khanlari at 11:21 PM | Comments (0)

Comparison of tropicamide and cyclopentolate for cycloplegic refractions in myopic adult refractive surgery patients

JCRS March 2005
The study was prospective, single center, with randomized sequencing of cycloplegic agent; each patient received both agents. Thirty consecutive myopic adult refractive surgery patients (mean age 35.4 years) participated. A complete preoperative examination, including cycloplegic refraction, was obtained twice, 1 week apart. The patient and the examiner were masked to the medication. Main outcome measures included cycloplegic and manifest refractions, best corrected distance acuity, near-point accommodation, pupil diameters, and subjective appraisal of experience with cycloplegic agents.Twenty-eight of 30 patients completed both examinations. Both eyes were measured, but comparisons were limited to right and left eyes, independently. No statistically significant difference was found between the tropicamide and cyclopentolate cycloplegic refractions (ConclusionsThere was no statistically significant difference in mean cycloplegic refractions. Cyclopentolate was more effective than tropicamide in reducing accommodative amplitude in adult myopes (near-point testing). Patients strongly preferred tropicamide.

Posted by mehdi khanlari at 11:05 PM | Comments (0)

Regenera, Alcon enter licensing agreement

OSN March 2005
PERTH, Australia – Alcon has licensed a product “that is used to assist in visualization of the vitreous fluid” during vitrectomy, according to a press release from Regenera.

Posted by mehdi khanlari at 11:02 PM | Comments (0)

Implant for artificial vision nears clinical trial

OSN March 2005
A computer chip linked to a minicomputer camera mounted onto a pair of glasses may eventually offer limited “sight” to blind people, according to one of its developers. Human trials of this device will begin within the year Dr. Dagnelie said the camera transmits images to the chip, which translates them into impulses the brain can interpret, according to a BBC News report. Dr. Dagnelie described his work with the device at a Royal National Institute for the Blind conference in London, the BBC said.The images may not be crystal clear, he said, but they may allow someone who is blind to recognize faces.“The retinal implant contains tiny electrodes. If you stimulate a single electrode, the person will see a single dot of light,” he told BBC.An implant with a handful of electrodes has previously been tested, Dr. Dagnelie said, but the device should eventually include up to 100 electrodes.

Posted by mehdi khanlari at 10:58 PM | Comments (0)

Bausch & Lomb offers online calculator for toric contact lenses

OSN March 2005

ROCHESTER, N.Y. — Bausch & Lomb introduces a new, free online resource for eye care professionals designed to further streamline the simplified process of fitting astigmatic patients, according to a company press release.Professionals simply enter the patient’s best sphero-cylindrical refraction or spectacle prescription and appropriate vertex distance. The software then determines the most appropriate SofLens66 Toric lens and automatically adjusts the spherical equivalent when selecting the nearest available cylinder power in the toric range.The calculator delivers speedy and accurate results, which improve office efficiency and reduce chair time for patients.

Posted by mehdi khanlari at 10:51 PM | Comments (0)

Pigment dispersion and Artisan phakic intraocular lenses: Crystalline lens rise as a safety criterion

JCRS APRIL 2005France,To validate the theory that crystalline lens rise can be used as a safety criterion to prevent pigment dispersion in eyes with an Artisan phakic intraocular lens (IOL) (Ophtec BV).
A comparative analysis of crystalline lens rise in 9 eyes with pigment dispersion and 78 eyes without dispersion was performed. All eyes had previous implantation of an Artisan IOL. Anterior segment imaging was done using an anterior chamber optical coherence tomography (AC OCT) prototype. Crystalline lens rise was defined by the distance between the anterior pole of the crystalline lens and the horizontal plane joining the opposite iridocorneal recesses.
Conclusions
Crystalline lens rise should be considered a new safety criterion for Artisan phakic IOL implantation and should also be applied to other types of phakic IOLs. The distance remaining between the crystalline lens rise and a 600 μm theoretical safety level allows one to calculate how long the IOL can safely remain in the eye

Posted by alireza habibollahi at 10:48 PM | Comments (0)

floppy iris syndrome associated with tamsulosin(IFIS)

JCRS APRIL 2005
USA.A retrospective chart review of consecutive cataract surgeries performed in a 2-surgeon practice over a 12-month period (706 eyes; 511 patients) was used to assess the percentage of cataract patients on systemic sympathetic α-1 antagonist medications as well as the percentage of patients who manifested the IFIS.
Conclusion
Intraoperative floppy iris syndrome occurred in approximately 2% of a cataract surgery population and appeared to be caused by tamsulosin, a systemic sympathetic α-1A antagonist(Flomax) medication that is the most frequently prescribed medication for benign prostatic hypertrophy. Sphincterotomies and mechanical pupil stretching were ineffective in maintaining adequate pupil dilation in this surgical population.

Posted by alireza habibollahi at 10:39 PM | Comments (0)

Slitlamp biomicroscopy of the tear film of patients using topical Restasis and Refresh Endura

JCRS APRIL 2005
We describe a technique in which slitlamp biomicroscopy is performed to evaluate eyes in patients using a topical dry-eye agent; ie, topical cyclosporine A ophthalmic emulsion 0.05% (Restasis) or glycerin 1%–polysorbate 80 1% (Refresh Endura). Both are delivered in an oil-emulsion formulation. We also describe a previously unreported physical finding in the tear film of these patients. The examination technique can help confirm patient compliance and the tear-film stability of the 2 agents.

Posted by alireza habibollahi at 10:31 PM | Comments (0)

May 21, 2005

Conductive Keratoplasty and the Coupling Phenomenon

Eye & Contact Lens: Science & Clinical Practice. 31(3):111-116, May 2005

Purpose. To determine whether changes in corneal astigmatism with astigmatic conductive keratoplasty (CK) treatment obey Gaussian coupling (i.e., the steepening of the flat axis associated with the flattening of the steep axis) and to measure the coupling ratio and the coupling constant to determine the effect of astigmatic CK treatment on spherical equivalent.
Methods. Retrospective review of 33 eyes in 24 patients who had undergone CK for hyperopia and who were treated intraoperatively for induced astigmatism. Induced astigmatism was determined by comparison of keratometric readings before and after CK.
Results. The coupling ratio was calculated according to two equations: clinical coupling ratio (1.61 +/- 0.81 diopters) and coupling ratio of the surgically induced refractive change (1.57 +/- 1.16 diopters). Values of the coupling ratio between 0.72 and 1.88 indicate coupling.
Conclusions. The cornea does not behave according to Gauss's law of elastic domes. The targeted flat axis and steep axis 90[degrees] away are affected by CK in opposite but not equal amounts. Therefore, when correcting surgically induced astigmatism with CK, the overall spherical equivalent of the patient will change because the coupling ratio is not equal to 1.

Posted by mmiraftab at 10:29 PM | Comments (0)

Lisch Corneal Dystrophy

Cornea. 24(4):494-495, May 2005

Lisch established in his article in 1992 some clinical and histologic features that distinguish these cases from other epithelial dystrophies. These clinical findings and histopathologic results were characteristic of this new band-shaped microcystic epithelial dystrophy.
The lesions always have a gray, band-shaped, and feathery pattern and appear also sometimes in a whorled form. Slit-lamp examination reveals these opacities to consist of densely crowded clear intraepithelial microcysts, which are better seen with retroillumination. No fluorescein or rose bengal staining can be observed. No epithelial erosions are present.
Symptoms are usually gradual worsening of visual acuity (especially when the visual axis is affected), blurry vision, and sometimes monocular diplopia; in some cases, patients are asymptomatic and lesions are found incidentally. No concomitant alterations of palpebral conjunctivae or physical factors that suggest a mechanical pathogenesis have been described.
Light microscopy shows a bubbly vacuolization at all levels of the epithelial cytoplasm, most evident at the wing cell layer, with a sharp delineation from non affected areas.1 No periodic acid-Schiff nor Alcian blue acid mucopolysaccharide staining is present.3
Electron microscopy reveals intracytoplasmic vacuoles that look optically empty or containing weakly osmophilic, partly homogeneous, and partly lamellar material.The vacuoles tend to coalesce, finally resulting in a structureless transparent cytoplasm.
Lisch dystrophy should be distinguished from other corneal diseases that would have a similar appearance.
Meesmann dystrophy shows also small, discrete, grayish intraepithelial bubbles that appear as clear microcysts with retroillumination. These epithelial cysts present in a bilateral diffuse distribution that is more prominent in the interpalpebral area in contrast to the asymmetric, densely crowded pattern of Lisch dystrophy. The intracystic cellular debris in Meesmann disease stains Alcian blue and PAS positive. These patients report recurrent ocular pain because of epithelial erosions caused by rupture of superficial cysts, which does not occur in Lisch dystrophy. A recent genetic study also concluded that Lisch and Meesmann dystrophies are genetically distinct and mapped to different chromosomal loci.

Posted by mmiraftab at 10:08 PM | Comments (0)

May 20, 2005

After-cataract in children having cataract surgery with or without anterior vitrectomy implanted with a single-piece AcrySof IOL

journal of Cataract April 2005,

Cataract surgery was performed in 66 children aged 3 to 15 years. They were randomized to surgery with or without anterior vitrectomy. All eyes were implanted with the single-piece AcrySof SA30AL IOL (Alcon). During the study, the patients who needed surgery for after-cataract had a second surgical procedure. Two years after surgery, the surgical method was evaluated using exact logistic regression. Also, the Evaluation of Posterior Capsule Opacification (EPCO) score was compared between the patients who had surgery for after-cataract and the patients who did not need this. The presence of posterior synechias and centration of the IOL were assessed.ResultsChildren in the younger age group (≤62 months at surgery) had surgery for after-cataract more often than children in the older age group (P<.01). Patients who did not receive an anterior vitrectomy had surgery for after-cataract more often (P<.01). Age at surgery and whether an anterior vitrectomy was performed did not significantly affect the EPCO score. The patients who had surgery for after-cataract had a significantly higher EPCO score (P<.001). The IOL remained centered in all eyes; no eye developed posterior synechiasConclusionsThis prospective study shows that cataract surgery with anterior vitrectomy is advantageous in younger patients concerning after-cataract formation. The AcrySof SA30AL maintains good centration, produces minimal inflammation, and is well tolerated in the pediatric eye.

Posted by mehdi khanlari at 08:53 PM | Comments (0)

Cataracts in children

JCRS,April,2005
Bilateral congenital cataract is the most common cause of treatable childhood blindness. Nuclear cataract is usually present at birth and is nonprogressive, whereas lamellar cataract usually develops later and is progressive. Surgery must be performed promptly in cases with dense congenital cataract; if nystagmus has developed, the amblyopia is irreversible. A treatment regimen based on surgery within 2 months of birth combined with prompt optical correction of the aphakia and aggressive occlusion therapy with frequent follow-up has been successful in unilateral and bilateral cases. Both anterior and posterior capsulorhexes are performed in most children. Intraocular lens implantation can be performed safely in children older than 1 year. Anterior dry vitrectomy is recommended in preschool children to avoid after-cataract. Opacification of the visual axis is the most common complication of cataract surgery in children. Secondary glaucoma is the most sight-threatening complication and is common if surgery is performed early. Life-long follow-up is essential in these cases.

Posted by afarahi at 08:37 PM | Comments (0)

Discoid Lupus Erythematosus Masquerading as Chronic Blepharoconjunctivitis

Ophthalmology , May, 2005
Records of 5 patients with biopsy-proven DLE were reviewed.
Clinical features included meibomian gland dysfunction, blepharitis, chalazia, trichiasis, madarosis, conjunctivitis, chronic eyelid edema, and eyelid plaques. Histopathology showed hyperkeratotic epithelium, degeneration of the basal cell layer, and a perivascular lymphocytic infiltrate. There was delayed diagnosis in all cases, ranging from 4 months to 25 years. All of the patients responded to systemic hydroxychloroquine therapy.
Conclusions:Heightened awareness of eyelid DLE may lead to earlier detection and specific therapy for this chronic disorder.

Posted by afarahi at 08:25 PM | Comments (0)

Corneal thickness not associated with eye length

Eyeworld March 2005
Thin corneas are not associated with long eyes, a study found. Central corneal thickness and axial length are independent occurrences and have no statistical association with each other, according to the study authors.Mitsugu Shimmyo, MD, and Paul Orloff, MD, of the Manhattan Eye, Ear and Throat Hospital, performed the study to investigate whether a thin cornea, which has been identified as a risk factor for glaucoma, might be associated with a weak sclera, an anatomic trait that might contribute to the vulnerability of the lamina cribrosa.The researchers reviewed the charts of 1,084 eyes of 546 patients to determine correlations between central corneal thickness and axial length. The mean age of the patients was 66 years, ranging from 9 to 93 years. The review included 540 eyes of Hispanic patients, 215 eyes of Asian patients, 212 eyes of white patients and 117 eyes of black patients. Fewer than 10% of the eyes had glaucoma. All the eyes had central corneal thicknesses and axial length measured by ultrasonic pachymetry.The mean central corneal thickness of all eyes was 543.1 µm, and the mean axial length was 23.44 mm.The total patient study group showed no statistically significant association between central corneal thickness and axial length. A subgroup analysis by age, gender and race also failed to support an associative relationship.

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

Spiral design in aspiration cannula may stabilize chamber during MICS

Eyeworld March 2005
A new cannula design for aspirating cortical material during phacoemulsification can improve fluidics by limiting aspiration during use of high vacuum settings “Intelligent tubing will allow our bimanual microincision phaco to become safer and more efficacious by increasing flow in the aspiration cannula without compromising chamber stability,” The cannula tubing proposed by Dr. Barrett is different from conventional tubing because it has a fluted, spiraling interior lumen, rather than the traditional cylindrical interior. The design creates more resistance to flow at higher rates of vacuum keeping the chamber stable during surgery.Dr. Barrett proposed other modifications of bimanual microincision phacoemulsification (MICS) that he said would add to the procedure’s safety and efficacy. He said a coaxial irrigation cannula with an elastic sleeve could enhance fluidics, while a coaxial phaco tip with a titanium sleeve might prevent wound burn. Additionally, creating a microincision of 2.6 mm or smaller would help reduce leakage at the surgical site and reduce astigmatism, he said.

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

Two-step technique better for post-PKP patients with astigmatism

Eyeworld March 2005
To determine whether it might be preferable to do the LASIK procedure in two stages, investigators launched a prospective observational study in which they divided 22 consecutive eyes into two groups.Those in group one underwent traditional one-step LASIK, while those in group two underwent the procedure in two steps — first the flap was cut and then one month later, the patient was re-evaluated and underwent the ablation.Results showed that those that underwent traditional LASIK did not fare as well as those in the other group.“They achieved less visual acuity and their visual performance was significantly decreased due to the induction of some amount of irregular astigmatism,” Dr. Alio said. “This irregular astigmatism was indeed created by the ablation on an unstable refraction that was changing just immediately after the cut.”One patient in the two-step group with 5 D of astigmatism was corrected by the LASIK cut alone.When the patient was evaluated before the ablation, there was less than 2 D of astigmatism remaining, making the ablation unnecessary.“In this case, an ablation would have changed the refractive outcome of the patient to a worse situation and indeed could have induced irregular astigmatism for sure To use the two-step approach in the clinical setting, Dr. Alio recommends first cutting the LASIK flap and then allowing the patient to stabilize before proceeding with the ablation.“I usually put in a contact lens for two or three days to assist the recovery of the corneal surface — loss of epithelium is frequent in these cases,” Dr. Alio said.He then waits a month before examining the patient’s topography and refraction again.After that follow-up visit, he waits another two weeks to ensure that the cornea is indeed stable.

Posted by mehdi khanlari at 07:41 PM | Comments (0)

Newest antibiotics no match for MRSAs

Eyeworld March 2005
Corneas infected with methicillin-resistant Staph aureus (MRSA) may not improve with application of either currently available fourth-generation fluoroquinolone alone, if recent cases are any indication.
The retrospective case series consisted of four corneal infections treated with the newest fluoroquinolones, which all cultured positive for gram-positive micro-organisms. Three of the four were positive for MRSA, and three of the four cases (including two with MRSA) resulted in corneal perforation. Also, two patients required emergent tectonic surgery Of these patients, the one with a stubborn ulcer eventually healed, another needed an emergency patch graft, and the third ultimately required an emergency central graft.
You can’t just assume these new medications are a magic bullet and once you start patients on moxifloxacin or gatifloxacin or any medication that they are not going to perforate or not going to have problems if not clinically managed carefully.”.....He recommends Gram and Giemsa vital staining along with culturing everyone with serious corneal ulcers, instead of not knowing whether they have an MRSA or some other bacteria. Depending on the findings of the patient cultures, Dr. Soukiasian said vancomycin (Vancocin, Eli Lilly, Indianapolis) and tobramycin (Tobrex, Alcon) are alternative drugs to the fourth-generation fluoroquinolones.In the general community, about 20% of corneal ulcers have MRSA, so patients Read more

Posted by mehdi khanlari at 04:19 PM | Comments (0)

Newest antibiotics no match for MRSAs

Eyeworld March 2005
Corneas infected with methicillin-resistant Staph aureus (MRSA) may not improve with application of either currently available fourth-generation fluoroquinolone alone, if recent cases are any indication.
The retrospective case series consisted of four corneal infections treated with the newest fluoroquinolones, which all cultured positive for gram-positive micro-organisms. Three of the four were positive for MRSA, and three of the four cases (including two with MRSA) resulted in corneal perforation. Also, two patients required emergent tectonic surgery Of these patients, the one with a stubborn ulcer eventually healed, another needed an emergency patch graft, and the third ultimately required an emergency central graft.
You can’t just assume these new medications are a magic bullet and once you start patients on moxifloxacin or gatifloxacin or any medication that they are not going to perforate or not going to have problems if not clinically managed carefully.”.....He recommends Gram and Giemsa vital staining along with culturing everyone with serious corneal ulcers, instead of not knowing whether they have an MRSA or some other bacteria. Depending on the findings of the patient cultures, Dr. Soukiasian said vancomycin (Vancocin, Eli Lilly, Indianapolis) and tobramycin (Tobrex, Alcon) are alternative drugs to the fourth-generation fluoroquinolones.In the general community, about 20% of corneal ulcers have MRSA, so patients Read more

Posted by mehdi khanlari at 04:19 PM | Comments (0)

Rezoom Approval

Posted by mehdi khanlari at 04:18 PM | Comments (0)

ASCRS Glaucoma Day News briefs

Eyeworld March 2005
Identifying glaucoma: Functional or structural changes?
Various studies have found structural changes occurring first in 17% to 55% of glaucoma patients, while other studies have identified functional damage occurring before structural damage in 18% to 86% of glaucoma patients. “It points out the necessity of performing both kinds of exams,”
Drainage device deemed helpful
A device designed to relieve the symptoms of glaucoma promises to become more useful as surgeons develop more advanced methods of glaucoma treatment. The Eyepass Glaucoma Implant (GMP Companies Inc., Fort Lauderdale, Fla.) will enable surgeons to “basically do whatever they want,” said Reay Brown, M.D., Atlanta. Dr. Brown said he is convinced that once the implant becomes a regular method applied to glaucoma patients, technology will be developed to make it a more effective drainage tool. The implant has advanced to the third and final round for approval from the Food and Drug Administration.
Basic online glaucoma risk calculator developed
The Devers Eye Institute, Portland, Ore., has developed and launched an online ocular hypertension-to-glaucoma risk calculator The calculator, located through Dever’s Web site (www.discoveriesinsight.org), uses data from the Ocular Hypertension Treatment Study (OHTS) to allow ophthalmologists to identify specific patients’ risk for developing glaucoma. The Web site allows input of various patient parameters, including age, diabetes status, corneal thickness, and IOP. There are many additional “art of medicine” factors the calculator does not take into account, such as life expectancy, Dr. Cioffi said, which could further refine a diagnosis.
Variety of IOP measurements needed
Ophthalmologists likely are not identifying their patients’ peak IOP spikes because recent research has found patients’ highest IOP measurements typically occur overnight, shortly before a patient awakens, said Dr. Weinreb. The finding that 67% of peak IOP measurements are obtained outside of normal office hours contradicts the long-held belief that the highest IOP occurs in the early morning. The research also has identified that supine IOP measurements are invariably higher than those taken from a sitting patient, regardless of the time of day. The finding is significant, because other research has linked IOP variation to increased risk of progression. Dr. Weinreb said ophthalmologists can better determine their patients’ IOP through 24-hour monitoring, which may be impractical, or a predictor with supine office management.
Goldmann’s accuracy uncertain
The accuracy of Goldmann applanation tonometry (GAT, Haag Strait, Mason, Ohio), the gold standard of IOP measurement, has been called into question by recent research, said James D. Brandt, M.D., The reason is the expanded understanding of the significant impact of central corneal thickness (CCT) on IOP measurements. The GAT system design was based on a CCT of 500 microns, and varies for deviations from that value. However, research has shown CCT varies greatly from the 500-micron “patient average.” Dr. Brandt advised ophthalmologists to filter their IOP measurements through an understanding of which general category of CCT — thick, thin or average — that patient fits.
LTP benefits highlighted
Laser trabeculoplasty (LTP) is the best initial therapy for pseudoexfoliation It’s more effective than other treatments to lower IOP, and it’s usually more cost effective, said Dr. Berlin. The treatment also has few post-op complications. If necessary, physicians can follow up with more therapy after LTP. With the advent of selective laser trabeculoplasty, there’s an even greater indication for LTP, said Dr. Berlin. Although Kuldev Singh, M.D., M.P.H., associate professor of ophthalmology, Stanford (Calif.) University Medical Center, agrees that LTP is effective, but he doesn’t think it’s the best initial treatment for pseudoexfoliation. “The IOP decreases with LTP but the [IOP] fluctuations aren’t decreased,” said Dr. Singh. A better treatment is to start with prostaglandins and then try LTP, said Dr. Singh.
Beware “Glaucoma Bermuda Triangle”
Remove a pseudoexfoliation cataract as early as possible, said Reay Brown, M.D., Atlanta. When you remove the cataract, you’ll see a softer nucleus, stronger zonules, less advanced glaucoma, and a decreased risk for IOP spikes. You also can help avoid what Dr. Brown calls the “Glaucoma Bermuda Triangle,” where you perform a trabeculectomy for IOP spikes, followed by a worsened cataract for which phacoemulsification and IOL implantation are performed, and then a repeat trabeculectomy for bleb failure.

Posted by mehdi khanlari at 12:11 PM | Comments (0)

FDA aprroved Restore Lens

Eyeworld March 2005

Posted by mehdi khanlari at 12:07 PM | Comments (0)

May 19, 2005

Retinal stem cell research has yielded ‘spectacular progress,’ but challenges lie ahead

OSN 2005
The field of retinal stem cell research has seen great advances in the past decade, but work still lies ahead. There are spectacular seeks to replace degenerated photoreceptor cells with healthy cells. When photoreceptors die, they don’t come back. One problem with culturing stem cells is that, at present, there is “no magic bullet” to turn progenitor cells into mature synaptically connected photoreceptors. What we need is a growth factor that would speed up the transformation. Stem cells used in retinal research are often taken from the ciliary marginal zone of the retina. The advantage of stem cells is their “multipotentiality” and “self-renewal,” which makes them ideal tools for ocular tissue regeneration. In culture, one human stem cell can proliferate to 10,000 stem cells in just a week. Cell integration and biocompatibility is crucial to success whether dealing with stem cells or with implanted artificial tissue. Speaking about retinal prostheses, improving the “interface” of foreign material implanted in diseased or degenerative tissue may be achieved through therapeutic adjuncts. Drug delivery may be helpful in fighting off rejection of retinal prostheses and will improve the biocompatibility of the prosthesis.

Posted by kjalali at 06:57 PM | Comments (0)

Visual field changes after laser in situ keratomileusis

Journal of Cataract & Refractive Surgery Volume 31, Issue 4 , April 2005, Pages 687-693

This nonrandomized clinical trial comprised 14 normal patients (27 eyes) scheduled to have LASIK for myopia or myopic astigmatism. Automated static perimetry was performed before and 6 months after surgery using the Octopus 1-2-3 perimeter and the Dynamic-32 test strategy. Patient data included sex, age, preoperative and postoperative refractive errors, preoperative and postoperative best corrected visual acuity, preoperative corneal thickness, programmed optical zone, programmed total ablation diameter, and duration of microkeratome suction. All surgery was performed using the same Alcon LADARVision 4000 excimer laser. The main outcome measures were the mean sensitivity (MS) change in the central 15-degree visual field and the MS change in the 15- to 30-degree visual field. A multivariate analysis of the MS change as a function of preoperative clinical parameters was performed.
Results
There was no significant change in the MS in the central 15-degree visual field; between 15 and 30 degrees, there was a statistically significant decrease of −0.82 dB ± 1.40 (SD) (P = .01, 2-tailed t test). The decline in MS was positively correlated with refractive error and corneal thickness; it was negatively correlated with the programmed optical zone diameter.
Conclusions
Automatic static perimetry can detect decreased sensitivity in the midperipheral visual field after myopic LASIK. It may be a useful quantitative subjective test for measuring the effects of future improvements in surgical technique on vision quality.

Posted by mmiraftab at 06:53 PM | Comments (0)

Pigment dispersion and Artisan phakic intraocular lenses :Crystalline lens rise as a safety criterion

Journal of Cataract & Refractive Surgery Volume 31, Issue 4 , April 2005, Pages 674-680

Georges Baïkoff MD,
A comparative analysis of crystalline lens rise in 9 eyes with pigment dispersion and 78 eyes without dispersion was performed. All eyes had previous implantation of an Artisan IOL. Anterior segment imaging was done using an anterior chamber optical coherence tomography (AC OCT) prototype. Crystalline lens rise was defined by the distance between the anterior pole of the crystalline lens and the horizontal plane joining the opposite iridocorneal recesses.
Results
The study confirmed that crystalline lens rise can be considered a safety criterion for implantation of Artisan-type phakic IOLs. The higher the crystalline lens rise, the greater the risk for developing pigment dispersion in the area of the pupil. This complication occurred more frequently in hyperopic eyes than in myopic eyes. Results indicate there is little or no risk for pigment dispersion if the rise is less than 600 μm; 67% of eyes with a rise of 600 μm or more developed pupillary pigment dispersion. In some cases in which the IOL was loosely fixated, there was no traction on the iris root and dispersion was prevented or delayed.
Conclusions
Crystalline lens rise should be considered a new safety criterion for Artisan phakic IOL implantation and should also be applied to other types of phakic IOLs. The distance remaining between the crystalline lens rise and a 600 μm theoretical safety level allows one to calculate how long the IOL can safely remain in the eye.

Posted by mmiraftab at 06:51 PM | Comments (0)

Effectiveness of intravitreal triamcinolone acetonide for cystoid macular edema in central retinal vein occlusion is short-lived

American Journal of Ophthalmology, May 2005
The injection is very effective in reversing cystoid macular edema and improving visual acuity in recent-onset nonischemic central retinal vein occlusion in the first six months of treatment. But the improvement deteriorated at one year. The drug did not prevent collateral circulation formation, which was seen in 10 of the 18 patients studied.

Posted by kjalali at 06:51 PM | Comments (0)

Surodex effective in phacotrabeculectomy surgery

American Journal of Ophthalmology, May 2005
Patients with primary open-angle glaucoma who underwent surgery augmented by intra-scleral placement of Surodex had good IOP control (20.1 percent decrease) and a low postoperative complication rate (8.1 percent), compared to patients who underwent surgery augmented with 50 mg/ml of intraoperative 5-fluorouracil (5-FU), who experienced a 28.5 percent decrease in IOP and a complication rate of 19.3 percent. Surodex is a drug delivery system incorporating 60 micrograms of dexamethasone in a pellet.

Posted by kjalali at 06:49 PM | Comments (0)

Intralesional triamcinolone acetonide injection appears effective in treating primary and recurrent chalazia

Ophthalmology, May 2005
The drug reduced lesion size by at least 80 percent in most patients. Most cases resolved with an average of one to two injections. Chalazia that fail to respond to two or three injections are more likely to benefit from surgical excision. The authors suggest injections be considered a first treatment in straightforward cases.

Posted by kjalali at 06:47 PM | Comments (0)

Hyaluronidase may prevent diplopia after peribulbar anesthesia for cataract surgery

Ophthalmology, May 2005
No cases of diplopia occurred in patients undergoing surgery with hyaluronidase in the anesthetic solution, compared to 27 cases in the group receiving anesthesia without the drug. Diplopia involved the inferior rectus (40 percent) and the external rectus (37 percent) muscles, and was persistent in 54 percent of the cases.

Posted by kjalali at 06:46 PM | Comments (0)

Role of Hyaluronidase in Diplopia after Peribulbar Anesthesia for Cataract Surgery

Ophthalmology Volume 112, Issue 5 , May 2005, Pages 879-882

Seven thousand two hundred five patients were studied. During P1, 3582 patients received peribulbar anesthesia, and no cases of diplopia occurred. During P2, 3623 patients received peribulbar anesthesia, and 27 cases of diplopia occurred (incidence, 0.75%; P = 0.0002 vs. P1). Diplopia involved the inferior rectus (40%) and the external rectus (37%) muscles. Diplopia was persistent in 54% of the cases.
Conclusions
Peribulbar anesthesia-related diplopia was significantly more frequent when hyaluronidase was not added to the anesthetic solution.

Posted by mmiraftab at 06:46 PM | Comments (0)

Nanotechnology may one day deliver gene therapy to treat degenerative eye disease

Eurotimes May 2005
One of the biggest challenges facing the gene medicine industry is the problem of delivery.A technology may be wonderfully effective in vitro but unless it can be delivered to the specific tissues and cells where it is required, all the success in the test tube may amount to nothing. Consequently, there is enormous activity in the field of delivery technologies.
Although this column has often reported findings from researchers who have used viruses to deliver genes, French researchers have scored a major victory for a non-virus technique. If further research proves successful, the researchers believe that combining DNA with so-called “nanoparticles” may provide an alternative delivery system for gene therapy that is as good – if not better – than the standard virus-based delivery technique.
Researchers at the Institut National de la Santé et de la Recherche Médicale(INSERM) in Paris, led by Dr Riad Antoine Bejjani, revealed earlier this year that they had delivered DNA to retinal pigmentepithelium cells using nanotechnology.

Posted by mmiraftab at 06:37 PM | Comments (0)

May 17, 2005

Caution on tetracyclin usage

Eyeworld March 2005
......As we all know, we’ve been using tetracyclines for a long time now for meibomitis, and I used to feel very comfortable with this method of treatment. I used to write tetracycline prescriptions like water, but there was a paper in February 2004 issue of The Journal of the American Medical Association that looked at antibiotic risk and antibiotic use in relation to the risk of breast cancer. The investigators found that with the tetracyclines, that those women who cumulatively were on tetracycline for longer than seven weeks doubled their risk of getting breast cancer and doubled their risk of dying from breast cancer. The effect was related specifically to cumulative dose. Well, today there is a one in eight risk that a women will get breast cancer, so with chronic tetracyclines we are potentially increasing that risk to one in four — a real concern.As that paper came out, what I started doing was putting people with mild to moderate meibomitis or posterior blepharitis on omega-3 supplementation alone, and those with severe disease on low-dose doxycycline, 50 mg a day, along with omega-3 supplementation. What I’m able to do in those more severe patients is stop the doxycycline at four weeks and then maintain them on omega-3 supplementation alone.

Posted by mehdi khanlari at 10:58 PM | Comments (0)

May 16, 2005

Enucleation with Reverse Replacement of Sclera as an Alternative to Conventional Evisceration

Orbit,March,2005

Ten patients who underwent combined enucleation and evisceration with 3 to 36 months of follow-up were identified . The technique involved enucleation followed by evisceration of the eye contents. Implants, either coral or acrylic, were wrapped in the eviscerated sclera and replaced in the orbit with the posterior pole of the sclera facing anteriorly. The rectus muscles were then resutured onto the sclera. No complications were encountered, in particular no implant extrusions. Cosmesis was graded good in 9 out of 10 patients. Conclusion: Combined enucleation and evisceration allows the selection and placement of an appropriately large-sized implant to achieve good volume replacement with no extrusions in our series. This technique is particularly pertinent as an alternative to standard evisceration in phthisical eyes.

Posted by afarahi at 12:41 AM | Comments (0)

Repair of Medial Orbital Wall Fracture: Transcaruncular Approach

Orbit,March,2005
The aim of this paper is to demonstrate the safety and the use of the transcaruncular approach as a surgical technique for managing a medial wall fracture. This approach was used in 40 patients with a isolated medial or a combined medial and inferior orbital wall fracture. Conclusion: This approach provides a safe, rapid, and cosmetically pleasing surgical approach for managing a isolated medial wall fracture. When combined with the inferior transconjunctival approach, a combined medial and inferior orbital wall fracture can be successfully repaired

Posted by afarahi at 12:27 AM | Comments (0)

May 15, 2005

A novel method for diagnosis of dry eye

Eyeworld March 2005
In a related presentation at the ASCRS•ASOA Symposium & Congress, Dr. Latkany and Dr. Speaker presented a functional test that may help detect dry eye.Titled “Functional Test to Detect Dry Eye Syndrome,” the presentation highlighted the results of a study that compared the best corrected distance visual acuity of 40 dry eyes, and 40 eyes that were not dry.The goal was to improve how practitioners detect dry eye, which is often misdiagnosed and underdiagnosed. Dr. Latkany calls the test the Tear Normalization Test.Practitioners may be able to determine if a patient has dry eye by testing uncorrected distance visual acuity before and after instillation of an artificial tear drop, Dr. Latkany said. If the drop helps improve visual acuity, the patient most likely has dry eye.As part of the study, patients filled out an Ocular Surface Disease Index questionnaire form to determine the extent of their dry eye. All patients had a detailed slitlamp examination and Schirmer testing.Eighty-three percent of the time, the test was able to detect dry eye. The best dry-eye indicator was two lines or more of visual acuity improvement after artificial tear drop was instilled, said Dr. Latkany. “The test is simple and helps nail down a diagnosis,” he said.

Posted by mehdi khanlari at 11:15 PM | Comments (0)

Punctal plugs may help presbyopic dry-eye patients

Eyeworld March 2005
Punctal plugs may help improve the uncorrected near visual acuity of presbyopic dry-eye patients .Results included 34 eyes with plugs and 16 control eyes. The study focused on testing uncorrected and best-corrected near visual acuity in patients over the age of 40 with mild to severe dry eye.After plug insertion, 20.6% of patients had zero or one line of visual acuity improvement, 59% had two lines of improvement, and 20.6% had three lines of improvement or greater. The P value of the results was .0001.The uncorrected and best-corrected near visual acuity were tested before and after punctal plug placement. They were also measured when an artificial tear drop was placed in the eye after the punctal plugs were inserted.Visual acuity was reassessed every minute until it returned to its pre-tear drop acuity. The artificial tear drops also helped extend how long patients’ visual acuity improved.The punctal plugs and artificial tear drops help decrease aberrations on the optical tear film, which improves image quality

Posted by mehdi khanlari at 10:50 PM | Comments (0)

Mitomycin C found to decrease corneal haze after PRK

Eyeworld March 2005
A recent study has found that topical mitomycin C (MMC) significantly decreases corneal haze formation in rabbits after photorefractive keratectomy (PRK) for high myopia. The study also found that decreased keratocyte density in the anterior stroma to be a possible warning sign for future complications.Researchers, led by Marcelo Netto, M.D., Cole Eye Institute and the Cleveland Clinic Foundation, Beachwood, Ohio, had sought to determine the effectiveness of MMC in stopping corneal haze after PRK by performing the procedure to correct –9.0 D in 64 New Zealand rabbits.The rabbits were divided into two groups: PRK plus BSS (Group 1) and PRK plus MMC (Group 2) for two minutes. They were then given a slitlamp analysis and haze grading.The slitlamp analysis showed significant differences in haze formation between Groups 1 and 2, with Group 2 – treated with MMC – realizing a significant reduction in keratocyte density in the anterior stroma (92.4 + 24), compared with Group 1 (141.8 + 28) at four weeks post-op.

Posted by mehdi khanlari at 10:45 PM | Comments (0)

Dry Eye and Pregnancy

Eyeworld March 2005
An extremely important factor in maintaining an adequate ocular surface is the presence of normal androgen levels, which are found in both sexes albeit in far higher concentration in male With aging, all hormone levels decrease and androgens reach critically low levels in females at a far younger age than males. Thus, the remarkably earlier onset of dry eye in the female population.As stated before, pregnancy markedly elevates hormone levels. This is generally a very healthy state, full of anticipation and very important bodily changes.The high levels of hormones that circulate during pregnancy — particularly in the last trimester — can create relative deficiencies in androgen levels and marked alterations in the estrogen to androgen ratio, effectively decreasing androgen effects upon the ocular surface. Androgens may actually be severely decreased during pregnancy and lactation thereafter.First trimester nausea and vomiting, seen more commonly in first pregnancies, may lead to dehydration. In addition, anti-emetics considered safe for pregnancy may also induce ocular surface drying by decreasing aqueous tear production.Thus, yet another precautionary warning is in order for expectant women that experience the misery of persistent nausea accompanied by fluid loss, poor fluid intake, and medications that dry mucous membranes. This situation is particularly concerning in contact lens wearers.Certainly, the pregnant female should be well aware of dry eye symptoms, particularly if she has had dry eye before or suffers from any of the other risk factors for dry eye. The greatest danger may occur in contact lens wearers, who are already at increased risk of corneal infections. Further drying due to pregnancy may add to this infection risk.

Posted by mehdi khanlari at 10:33 PM | Comments (0)

The New Ladar 6000

JCRS Today May 2005
The technology is easy to use and allows Customcornea to treat more patients.Soon to be approved by the FDA, the Ladar 6000 excimer laser is the newest addition to the Ladarvision System (Alcon Laboratories, Inc., Fort Worth, TX). The Ladar 6000 excimer laser exceeds the significant technological advances of the company’s Ladarvision 4000, which improved visual outcomes.the Ladar 6000 excimer laser is better technology that is easier to use, and it will immediately be able to treat the full range of patients that can be treated on the Ladarvision 4000 today. All of the improvements to its design aim to save time, improve patient flow, and enhance procedural accuracy. The automatic registration process introduces an even greater level of precision to the already excellent outcomes surgeons are achieving with the Ladarvision 4000 excimer laser system.

Posted by mmiraftab at 12:04 PM | Comments (0)

Ocular Vasodynamic Changes in Light and Darkness in Smokers

Investigative Ophthalmology and Visual Science. 2005;46:1698-1705

CONCLUSIONS. The normal capacity for increased blood flow velocity in the central retinal artery in darkness was markedly reduced in smokers. This finding may explain the reduced dark vision after recent smoking reported in several studies and probably reflects the combined effects of an increased blood viscosity, the vasoconstrictive action of nicotine, and a reduced capacity of the blood to transport oxygen, as the hemoglobin is partly occupied by carbon monoxide.

Posted by mmiraftab at 11:46 AM | Comments (0)

Repeatability of Corneal Topography Measurement in Keratoconus with the TMS-1

Optometry & Vision Science. 82(5):405-415, May 2005

Purpose. The purpose of this study was to report the test-retest variability of simulated indices derived from the TMS-1 topography instrument (Tomey Technology, Waltham, MA) in keratoconus subjects enrolled in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study.
Methods. Four images were taken at an initial visit and at a repeat visit several weeks later. From these images, 17 indices were simulated from published formulas. Mixed-model analysis was used on test-retest data from the TMS-1 videokeratography instrument during the baseline year. This analysis yields estimates of within- and between-visit variability.
Results. Repeatability analysis revealed that within-visit standard errors were 1.0 to 5.9 times greater in keratoconus eyes than in normal controls when two images were analyzed from each visit. These values changed only slightly when more images were used. The ratio of between-visit standard errors of the indices were nearly equally greater than normal controls for (0.9-4.6 and 0.9-4.3) two images per eye and all images per eye, respectively.
Conclusions. These results suggest that the repeatability of simulated indices derived from TMS-1 topography in keratoconus subjects is poorer than in normal controls.

Posted by mmiraftab at 11:43 AM | Comments (0)

Image Metrics for Predicting Subjective Image Quality

Optometry & Vision Science. 82(5):358-369, May 2005

Purpose. Despite the proliferation of wavefront sensors to characterize the optical quality of individual eyes, there is not yet an accurate way to determine from a wave aberration how severely it will impact the patient's vision. Some of the most commonly used metrics, such as RMS wavefront error and the Strehl ratio, predict subjective image quality poorly. Our goal is to establish a better metric to predict subjective image quality from the wave aberration.
Methods. We describe three kinds of experiments designed to compare the effectiveness of different metrics in determining the subjective impact of the wave aberration. Subjects viewed a visual stimulus through a deformable mirror in an adaptive optics system that compensated for the subject's wave aberration. In the first experiment, we show that some Zernike modes such as spherical aberration and defocus interact strongly in determining subjective image quality. In the second experiment, the subject's wave aberration was replaced by the wave aberration corresponding to an individual Zernike mode. The subject then adjusted the coefficient of the Zernike mode to match the blur of a standard stimulus. In the third experiment, the subject viewed the same stimulus through the wave aberration of one of 59 different postoperative patients who had undergone LASIK and matched the blur by adjusting defocus. We then determined which among many image quality metrics best predicted these matching data.
Results. RMS wavefront error was a poor predictor of the data, as was the Strehl ratio.
Conclusions. The neural sharpness metric best described the subjective sharpness of images viewed through the wave aberrations of real eyes. This metric can provide a single number that describes the subjective impact of each patient's wave aberration and will also increase the accuracy of refraction estimates from wavefront-based autorefractors and phoropters.

Posted by mmiraftab at 11:39 AM | Comments (0)

Intraocular Pressure Measurements After Conductive Keratoplasty

Journal of Refractive Surgery Vol. 21 No. 2 March/April 2005

To determine the possible impact of conductive keratoplasty (CK) on intraocular pressure (IOP) measurements.
METHODS
A prospective, single-center, noncomparative interventional case series was performed. Baseline and postoperative IOPs were measured by Goldmann applanation tonometry in 32 eyes of 18 patients who underwent CK for hyperopia correction. Mean follow-up was 11.9 months (range: 8 to 18 months).
RESULTS
After CK, a statistically significant decrease in the measured IOP was observed (before CK: 14.22±1.64 vs after CK: 12.66±2.21, P<.001). The change in IOP readings postoperatively was not correlated with age, sex, keratometric readings, or attempted correction.
CONCLUSIONS
Despite the limitations due to the small number of patients enrolled in this study, the applanation tonometer appears to underestimate the true IOP after CK.

Posted by mmiraftab at 11:34 AM | Comments (0)

World Cornea Congress V News briefs

Eyeworld March 2005
Age may affect success of cornea transplant
The study is key to determine what pre-op factors influence endothelial function after PK. Typically, current donor recipients live longer and many young donors are lost, which results in donor shortages. Future studies on endothelial function are needed to improve the long-term outcomes.
PKP offers enormous benefits
In a cohort study of 217 patients, 75 patients had visual improvement one year after PKP. One gauge of the success was the report of reading fine print: 21 could read it pre-op; 44 could read it after one year; and 46 could read it after two years.
Organisms may plague punctal plugs
Pathogenic organisms may invade punctal plugs through the forming of biofilm, thus modifying the microbial flora of the lid margin, and/or conjuctiva
Glue works in failed PKP cases
A modified sclerokeratoplasty using fibrin glue instead of sutures allowed fast post-op recovery, with low complications and good visual results, according to a study of 24 cases. The surgery was performed on patients previously submitted for complicated intraocular surgery and failed PKP, with heavy immune reaction and poor prognosis. “We think this facilitates the prognosis of lamellar sclerokeratoplasty,” he said. The lack of sutures and the total replacement of a diseased limbal recipient area seem to avoid the early rejection rate observed in this type of case
Ectasia patients provide pre-op clues
A retrospective evaluation of 4,350 consecutive eyes undergoing LASIK found all post-op ectasia cases displayed recognizable pre-op risk factors. The review found seven cases, or 0.16%, of progressive post-LASIK keratectasia. Dr. Murta said critical evaluation of Orbscan (Bausch & Lomb, Rochester, N.Y.) videokeratography is important to find the recognizable risk factors, including correlations to pre-op myopia and residual bed thickness.
Intrastromal ring reduces immune reaction
Performing PKP with an intrastromal ring designed to decrease post-op astigmatism reduced immune reaction in its recipients much more than in a non-ring PKP group, according to Jorg H. Krumeich, M.D., Bochum, Germany. The study compared 160 eyes that received an 8-mm cobalt-molybdenum-titanium alloy ring sutured into the PKP wound with 240 PKP patients without the ring. It unexpectedly found only two immune reactions, or 1.1%, in the ring group compared to 18, or 7.2%, in the non-ring group. “The ring protects severely damaged eyes by helping to stabilize them,” said Dr. Krumeich, who added that more research was needed to determine why it had an immunosuppressive reaction. The ring failed to meet its intended goal of reducing astigmatism in such patients.
Injected aquosous (aqueous) triamcinolone treats corneal rejection well
One intracamerular injection of 4 mg of aquosous (aqueous) triamcinolone is an effective way to treat corneal endothelial rejection after penetrating keratoplasty,studied 29 eyes in 29 patients with acute endothelial rejection (ER). Sixteen eyes had diffuse ER. Twelve presented with 2/3 of their corneas with ER. One presented with 1/3 of the cornea with ER. According to Dr. Sousa’s scientific poster at the World Cornea Congress V, 81.5% of patients showed an improvement in corneal edema and at least two Snellen lines within 15 days. However, three patients presented with a recurrence of endothelial rejection after 30 days.
Mitomycin C may work well for treating PAM with atypia
Mitomycin C may be a superior alternative to surgical management of primary acquired melanosis (PAM) with atypia, one researcher said. All 12 patients with PAM experienced complete or partial disappearance of PAM. Prior to treatment, six patients had diffuse PAM and six had localized PAM. Patient ages ranged from 12 to 78, and half were female.
Fibrin glue possibly better than sutures
Fibrin glue (Tisseel VH, Baxter Healthcare, Deerfield, Ill.) increases patient comfort and shortens the duration of pterygium surgery compared to sutures Average surgical time was 13 minutes for the glue group, which was significantly less time than the 21 minutes for the suture group. In a second long-term study of 98 eyes using fibrin glue during pterygium surgery, all grafts survived. However, one had 1 mm of central necrosis which epithelialized soon thereafter.

Posted by mehdi khanlari at 07:27 AM | Comments (0)

World Cornea Congress V News briefs

Eyeworld March 2005
Age may affect success of cornea transplant
The study is key to determine what pre-op factors influence endothelial function after PK. Typically, current donor recipients live longer and many young donors are lost, which results in donor shortages. Future studies on endothelial function are needed to improve the long-term outcomes.
PKP offers enormous benefits
In a cohort study of 217 patients, 75 patients had visual improvement one year after PKP. One gauge of the success was the report of reading fine print: 21 could read it pre-op; 44 could read it after one year; and 46 could read it after two years.
Organisms may plague punctal plugs
Pathogenic organisms may invade punctal plugs through the forming of biofilm, thus modifying the microbial flora of the lid margin, and/or conjuctiva
Glue works in failed PKP cases
A modified sclerokeratoplasty using fibrin glue instead of sutures allowed fast post-op recovery, with low complications and good visual results, according to a study of 24 cases. The surgery was performed on patients previously submitted for complicated intraocular surgery and failed PKP, with heavy immune reaction and poor prognosis. “We think this facilitates the prognosis of lamellar sclerokeratoplasty,” he said. The lack of sutures and the total replacement of a diseased limbal recipient area seem to avoid the early rejection rate observed in this type of case
Ectasia patients provide pre-op clues
A retrospective evaluation of 4,350 consecutive eyes undergoing LASIK found all post-op ectasia cases displayed recognizable pre-op risk factors. The review found seven cases, or 0.16%, of progressive post-LASIK keratectasia. Dr. Murta said critical evaluation of Orbscan (Bausch & Lomb, Rochester, N.Y.) videokeratography is important to find the recognizable risk factors, including correlations to pre-op myopia and residual bed thickness.
Intrastromal ring reduces immune reaction
Performing PKP with an intrastromal ring designed to decrease post-op astigmatism reduced immune reaction in its recipients much more than in a non-ring PKP group, according to Jorg H. Krumeich, M.D., Bochum, Germany. The study compared 160 eyes that received an 8-mm cobalt-molybdenum-titanium alloy ring sutured into the PKP wound with 240 PKP patients without the ring. It unexpectedly found only two immune reactions, or 1.1%