Chorioretinal Lesions in Two Nonfatal Cases of West Nile
Ophthalmology
2003;135:1732–1736
Hershberger et al. report two cases of patients infected by the West Nile virus who presented with chorioretinal lesions.
Both patients were referred for blurred vision after experiencing an acute onset of a systemic febrile illness accompanied by myalgia, arthralgia, headache and a maculopapular rash.
Serologic testing for West Nile virus was positive in both patients. Ophthalmologic examination in each patient—one of whom was a 61-year-old woman, the other a 56-year-old man—revealed two unique features: unilateral iridocyclitis and very similar multifocal bilateral chorioretinal lesions with a “target-like” appearance resembling those reported in recent literature. The iridocyclitis in both patients was nongranulomatous, relatively mild and responded well to topical corticosteroids. One patient had mild disc edema in each eye. Both patients developed ocular symptoms seven to 14 days after onset of the systemic illness.
The authors conclude that while the association between the ocular findings and systemic illness remains presumptive, their observations demonstrate a strong likelihood that the ocular findings are directly related to West Nile virus.
Risk Extremely Low for Cataract Patients Using Anticoagulant or Antiplatelet Agents
Ophthalmology
2003;110:1784–1788
Should anticoagulant or antiplatelet agents be stopped prior to cataract surgery?
According to a study by Katz et al., the risks of medical and ophthalmic events associated with this procedure are so low that absolute differences in risk associated with these agents are minimal—despite the age of patients (72 years on average) and preexisting comorbidities such as angina, hypertension, a history of myocardial infarction and diabetes.
The prospective cohort study involved patients who were scheduled for 19,283 cataract surgeries at nine centers in the United States and Canada. All were at least 50 years old.
Rates of all adverse events were extremely low. Among those who routinely used anticoagulant or antiplatelet agents, there was no evidence to suggest that these patients were at increased risk of ocular hemorrhagic events, nor that those who discontinued use prior to surgery were at increased risk of medical events for which these medications are routinely prescribed.
The authors conclude that these data support the continued use of anticoagulants or antiplatelet agents among routine users.
Mathematical Models Chart the Changes in Corneal Curvature After Cataract Surgery Incisions
Ophthalmology
2003;110:1807–1813
To determine the effect of cataract surgery incisions on corneal curvature, Merriam et al. used analytic models of the magnitude and time course of change on the horizontal and vertical meridians of the cornea after five commonly used incisions in cataract surgery:
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extracapsular cataract extraction,
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6-millimeter superior scleral tunnel for phacoemulsification,
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3-mm superior scleral tunnel,
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3-mm temporal scleral tunnel and
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3-mm temporal corneal incision.
The models show that incisions on the superior meridian lead to an immediate steepening of the vertical meridian and flattening of the horizontal meridian, followed by a gradual flattening of the vertical meridian and steepening of the horizontal. Mean change on these meridians is coupled and symmetric, resulting in no significant change in mean spherical power.
In contrast, temporal incisions do not lead to measurable changes in the horizontal and vertical meridians.
The authors conclude that the average change in corneal curvature after cataract surgery incisions is predictable and can be described through a mathematical model.
Good Efficacy and Satisfaction With Transantral Orbital Decompression for Graves’ Optic Neuropathy
American Journal of Ophthalmology
2003;136:433–441
Soares-Welch et al. report the demographic characteristics, clinical features and long-term outcomes of patients with optic neuropathy of Graves’ disease after transantral orbital decompression.
In this retrospective noncomparative interventional case series, the investigators reviewed medical records and responses to two follow-up questionnaires concerning patient satisfaction.
Over a 20-year period, 215 patients underwent transantral orbital decompression for Graves’ optic neuropathy. In 205 eyes with visual acuity of 20/40 or worse before decompression, visual acuity improved by 3 Snellen lines or more in 110 (54 percent) of them. Of 291 eyes with visual field defects preoperatively, 120 (41 percent) had resolution, and 126 (43 percent) had improvement postoperatively. Proptosis was reduced in 350 eyes by 4.4 ± 2.3 millimeters. In 104 eyes, disk edema resolved in 72 (69 percent) and improved in 28 (27 percent).
Responses to questionnaires mailed in 1990 and 2000 showed that 76 percent and 88 percent of respondents, respectively, were subjectively satisfied with the results of orbital decompression.
The authors conclude that transantral orbital decompression appeared to be effective in treating optic neuropathy of Graves’ disease with patient satisfaction high at 10-year and 20-year follow-up.
Formulas to Determine IOL Power Calculations After Myopic LASIK
American Journal of Ophthalmology
2003;136:426–432
Shammas et al. describe and evaluate a refraction-derived method and a clinically derived method to calculate the correct corneal power for IOL power calculations after LASIK. They compare the results of these methods to the commonly used history-derived method.
In a retrospective consecutive series, 200 randomly selected eyes from 200 patients were evaluated before and after LASIK surgery. The cases were divided into two groups. The first group was used to derive two formulas; the second to validate those formulas.
The investigators obtained the pre-and post-LASIK spectacle refraction and the pre- (Kpre) and post-LASIK K (Kpost) readings. In each case, they calculated the pre- and post-LASIK refraction at the corneal plane and the amount of correction obtained by the refractive surgery (CRc).
They calculated the K values using the history-derived method (Kc.hd), in which Kc.hd=Kpre–CRc. They then compared Kc.hd to Kpost.
A value of 0.23 D for every diopter of myopia corrected at the corneal plane was used to calculate the corneal power using the refraction-derived method (Kc.rd), where Kc.rd=Kpost–0.23CRc.
A regression equation was also established by comparing on a scattergram the values of Kc.hd and Kpost in each case. This equation was used to develop a clinically derived method (Kc.cd), in which Kc.cd=1.14Kpost–6.8.
To validate the results, the authors compared the values obtained by the two methods with the Kc.hd values in the second group of cases. Kc.hd was used as the benchmark, and both Kc.rd and Kc.cd values correlated highly with Kc.hd when plotted on a scattergram, and there was no statistically significant difference between the mean keratometric values.
The authors conclude that the history-derived method is the standard and requires knowledge of the pre-LASIK K readings and of the amount of myopia corrected. The refraction-derived method can be used if the amount of myopic correction is known whether or not the pre-LASIK K readings are available. The clinically derived method depends only on the post-LASIK K readings and can be used when neither the pre-LASIK K readings nor the amount of correction is available.
Choroidal Neovascularization in Macular Degeneration: Predictors of Benefit From Verteporfin Therapy
American Journal of Ophthalmology
2003;136:407–418
What accounts for the variation in results found in different lesion compositions among prior placebo-controlled randomized clinical trials that evaluated photodynamic therapy with verteporfin (Visudyne) in patients with subfoveal choroidal neovascularization due to age-related macular degeneration? Investigators in this multicenter study tried to determine if those differences can be explained by variations in baseline lesion size and visual acuity.
Exploratory analyses were conducted in patients with predominantly classic or minimally classic lesions at enrollment in the Treatment of AMD With Photodynamic Therapy (TAP) Investigation and in AMD patients with occult with no classic CNV in the Verteporfin in Photodynamic Therapy (VIP) Trial.
At baseline, the mean size of predominantly classic lesions was smaller than that of minimally classic and occult with no classic lesions.
In a multiple linear regression model of individual lesion compositions, there was a significant treatment-by-lesion-size interaction for minimally classic and occult with no classic lesions, but not for predominantly classic lesions. Interaction between treatment and baseline visual acuity was not significant for any lesion composition. Small verteporfin-treated lesions lost less vision than large verteporfin-treated lesions in each lesion composition.
Lesion size was a more significant predictive factor for the magnitude of treatment benefit than either lesion composition or visual acuity. Smaller minimally classic and occult with no classic lesions had similar visual acuity outcomes to those observed in predominantly classic lesions.
Therefore, lesion size in the TAP Investigation and VIP Trial was an important predictor of the magnitude of treatment benefit with verteporfin therapy in occult with no classic and minimally classic lesion compositions.
In patients with AMD, treating smaller rather than larger neovascular lesions, regardless of lesion composition, may result in a better level of visual acuity.
Artisan Toric Phakic IOL for the Correction of High Astigmatism
American Journal of Ophthalmology
2003;136:442–447
Güell et al. researched the efficacy, predictability and safety of Artisan toric phakic IOL implantation to correct astigmatism higher than 2 D.
Twenty-seven eyes of 16 patients with a mean preoperative spherical equivalent of –11.78 ± 6.24 D and a mean preoperative astigmatism of –3.43 ± 0.81 D participated in this prospective study.
The Artisan phakic IOL was inserted into the anterior chamber through a posterior corneal incision, securing the lens in the correct axis. The main parameters evaluated in this study were uncorrected visual acuity, BCVA, refraction and endothelial cell count.
One year after the implantation of the Artisan toric phakic intraocular lens, 62.9 percent of the eyes were within
± 0.5 D of emmetropia and 96.2 percent were within ± 1 D; 70 percent of the eyes gained one or more lines from their preoperative BCVA; and 11.11 percent lost 1 Snellen line. Mean endothelial cell count increased in 2.9 percent and the mean of axis alignment error was 10.53 degrees. No serious complications were observed.
The authors conclude that the Artisan toric phakic IOL implantation appears to be a safe and predictable method for the correction of high levels of astigmatism.
Staining With Various Concentrations of ICG
American Journal of Ophthalmology
2003;136:223–230
Kwok et al. performed a prospective, randomized clinical trial to determine the effective minimal concentration of indocyanine green for staining the internal limiting membrane under air in macular surgeries.
Consecutive cases of macular hole (17 cases) and epiretinal membrane (11 cases) were randomized to receive one of the three concentrations of ICG: 0.25 milligrams per milliliter, 0.5 mg/ml and 1.25 mg/ml. The number of ICG injections, visual quality of the stained ILM and time used for ILM peeling were recorded. ILM specimens were subsequently examined under electron microscopy. Pre- and postop clinical data with fluorescein angiography were recorded.
There was a significantly smaller number of eyes with poor ILM staining in the 1.25 mg/ml group. There was no significant difference in the time required for ILM peeling among the three concentration groups or between the macular hole and ERM group. No ICG toxicity was found clinically or angiographically, except in one suspected case with ERM formation at the edge of ILM peeling. Electron microscopy of ILM specimens did not reveal any retinal elements.
The authors conclude that 1.25 mg/ml ICG under air stains the macular ILM consistently well for its removal in macular surgeries, but they cautioned that the safety of ICG-stained ILM peeling needs further evaluation.
Betaxolol for Persistent Macular Edema After Epiretinal Membrane Removal
American Journal of Ophthalmology
2003;136:244–251
Kobayashi et al. performed a prospective randomized clinical trial to determine the efficacy and safety of topical betaxolol (Betoptic) for treatment of persistent macular edema after epiretinal membrane removal.
Nineteen eyes of 19 patients received betaxolol twice daily and 18 eyes of 18 patients received placebo as a randomized comparison group. The patients were followed for six months, and investigators evaluated the effect of betaxolol on BCVA and area of macular edema, which was digitally measured on serial fluorescein angiograms.
Baseline mean BCVA and mean area of macular edema in the treatment and control group were not significantly different. Mean changes in log of minimal angle resolution of visual acuity for three- and six-month follow-up were significantly better statistically in the treatment group. Treated patients showed a significantly larger reduction in areas of macular edema than untreated patients at each examination. No complications associated with treatment or placebo were discovered. Topical betaxolol appears to have a favorable treatment effect in eyes with macular edema that remained after vitrectomy and removal of epiretinal membrane.
Endophthalmitis After Cataract Surgery: Clear Corneal vs. Scleral Tunnel Incisions
American Journal of Ophthalmology
2003;136:300–305
Cooper et al. performed a retrospective case control study of endophthalmitis following cataract surgery with a clear corneal incision (with or without placement of a suture) vs. scleral tunnel incision.
There were 38 patients treated for culture-positive, acute postcataract surgery endophthalmitis and 371 randomly selected control patients who underwent uncomplicated cataract surgery. Incision type and use of suture during cataract surgery of endophthalmitis cases were compared with the controls. The data were analyzed using logistic regression methods.
Of the 38 cases of endophthalmitis, 45 percent had clear corneal incisions and 55 percent had a scleral tunnel incision. In 371 controls, 20 percent had clear corneal incisions and 80 percent had scleral tunnel incisions. Clear corneal incision was associated with a threefold greater risk of endophthalmitis than was scleral tunnel incision. A clear corneal incision was more frequently associated with endophthalmitis. A subgroup analysis revealed that the presence or absence of a suture was not significant.
The authors conclude that there was a statistically significant higher risk of acute postcataract surgery endophthalmitis with clear corneal incisions compared with scleral tunnel incisions.
Dry Eye Syndrome Among Women
American Journal of Ophthalmology
2003;136:318–326
Although dry eye syndrome is common, there are few studies describing the magnitude of the problem in women and how this may vary with demographic characteristics.
Schaumberg et al. performed a cross-sectional prevalence survey of 39,876 U.S. women participating in the Women’s Health Study. For the survey, the syndrome was defined as the presence of clinically diagnosed dry eye syndrome or severe symptoms (both dryness and irritation constantly or often). The authors calculated the age-specific prevalence of the syndrome and adjusted the overall prevalence to the age-distribution of women in the U.S. population. They used logistic regression to analyze the data.
The prevalence of the syndrome increased with age, from 5.7 percent among women who are younger than 50 to 9.8 percent among women at least 75. Hispanic and Asian women were, compared with whites, more likely to report severe symptoms, but not clinically diagnosed dry eye syndrome. There were no significant differences by income, but more educated women were less likely to have the syndrome. Women from the South had the highest prevalence of the syndrome, though the size of geographic differences was modest.
Dry eye syndrome leading to a clinical diagnosis or severe symptoms is prevalent, affecting more than 3.2 million middle-aged and older American women. Although the condition is more prevalent among older women, it also affects many in their 40s and 50s.
Round-Up of Other Journals
Effect of 1 Percent Dorzolamide on Corneal Endothelium
Japanese Journal of Ophthalmology
2003;47:129–133
Inoue et al. have found that while topical 1 percent dorzolamide three-month treatment for patients with glaucoma increases central corneal thickness, it does not affect corneal endothelial morphology.
This trial involved 21 glaucoma patients (29 eyes). After three months of treatment, one patient experienced increased IOP from 13 mmHg to 19 mmHg, while the others showed a mean IOP decrease of 3.4 mmHg. The central corneal thickness increase after treatment was statistically significant, yet it is uncertain whether this difference is clinically significant.
Based on the short follow-up period in this study, the researchers recommend that the corneal endothelium continue to be observed in patients treated with topical 1 percent dorzolamide. They plan to evaluate next the influence of topical 0.5 percent dorzolamide treatment on endothelial morphology and corneal thickness.
Treating Severe Ocular Injuries
Retina
2003;23:48–56
Roters et al. retrospectively reviewed records of 34 severely injured eyes of 31 patients who underwent a combined procedure (penetrating keratoplasty with vitreoretinal surgery) to determine which factors impact corneal transplant success rates.
Penetrating keratoplasty was performed in 10 eyes within eight weeks of trauma and in 24 eyes as a secondary procedure. Initial improvement in visual acuity was achieved in 47 percent of eyes, and by the 12-month mark, 74 percent of the eyes had attained equal or better visual acuity than the initial postsurgical visual acuity. Poor final visual acuity was attributed to hypotony or phthisis and recurrent retinal detachment. In 65 percent of eyes, the corneal grafts remained clear for one year, with long-term graft survival dependent on the performance of keratoplasty later than two months after the injury, absence or removal of silicone oil with surgery, an attached retina, a minimum preoperative visual acuity of hand motions and the absence of further surgery.
The authors conclude that a study involving a larger number of patients is required to better understand the factors that influence corneal transplant success.
Vigabatrin vs. Tiagabine
Journal of Neurology, Neurosurgery and Psychiatry
2003;74:286 and 339–343
It has been well documented that the antiepileptic drug vigabatrin, an irreversible inhibitor of gamma-aminobutyric acid transaminase, has a tendency to produce visual field constriction by a toxic effect on the retina in about 40 percent of treated patients.
In contrast, according to new findings from a study by Krauss et al., tiagabine treatment, which blocks reuptake of glial and neuronal GABA, is associated with normal electroretinography and visual fields and ophthalmological function similar to patients taking other antiepilepsy drugs.
The study included adult volunteers with epilepsy (12 tiagabine, 32 vigabatrin and 14 control patients). The investigators found that while vigabatrin caused retinal electrophysiological changes in all patients treated, with visual function deficits occurring in a large proportion of patients, no evidence for similar visual disturbance in tiagabine patients occurred. This suggests that vigabatrin retinal toxicity is attributable to a specific effect on the retina. In an accompanying editorial, M.C. Lawden comments that a class effect of GABAergic drugs that causes retinal damage seems unlikely given the results from this study.
Excision Margins for Cutaneous Eyelid Skin Melanoma
Ophthalmic, Plastic and Reconstructive Surgery
2003;23:14–23
The Collaborative Eyelid Skin Melanoma Group conducted a retrospective survey of 44 patients with malignant melanoma of the periocular skin who had been treated by ophthalmic plastic and reconstructive surgeons in Europe and the United States.
They found that the size of excision margins was not related to the risk of local or regional recurrence or distant metastasis. In addition, the incidence of local or regional recurrence was not significantly higher among patients who had margins of 5 millimeters or less than among those who had larger excision margins. They cautioned, however, that the majority of patients in the study had thin melanomas and smaller excision margins.
The authors conclude that margins of at least 5 mm should be used when excising melanomas less than or equal to 1 mm thick, adding that individuals with tumors greater than or equal to 1 mm thick should be closely monitored for local or regional recurrence.
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Ophthalmology previews are written by Lori Baker Schena and edited by John Kerrison, MD. American Journal of Ophthalmolgy reviews are edited by Thomas J. Kiesegang, MD. Round-Up is written by Lori Baker Schena and edited by Jose S. Pulido, MD, MS, MBA.
