Thomas S. Stevens

Photocoagulation Treatment of Proliferative Diabetic Retinopathy: The Second Report of Diabetic Retinopathy Study Findings

Data from the Diabetic Retinopathy Study (DRS) show that photocoagulad inhibited the progression of retinopathy. These beneficial effects were noted to some degree in all those stages of diabetic retinopathy which were included in the Study. Some deleterious effects of treatment were also found, including losses of visual acuity and constriction of peripheral visual field. The risk of these harmful effects was considered acceptable in eyes with retinopathy in the moderate or severe retinopathy in the moderate or severe proliferative stage when the risk of severe visual loss without treatment was great. In early proliferative or severe nonproliferative retinopathy, when the risk of severe visual loss without treatment was less, the risks of harmful treatment effects assumed greater importance. In these earlier stages, DRS findings have not led to a clear choice between prompt treatment and deferral of treatment unless and until progression to a more severe stage occurs.

Immunostaining of Preretinal Membranes for Actin, Fibronectin, and Glial Fibrillary Acidic Protein

The frequency and extent of immunostaining for actin, fibronectin (FN), and glial fibrillary acidic protein (GFAP) were determined in 37 preretinal membranes (PRMs) obtained at vitrectomy from 35 patients with proliferative diabetic retinopathy (PDR) (n = 16), proliferative vitreoretinopathy (PVR) (n = 18), or idiopathic macular pucker (MP) (n = 3). All three proteins were detected in the vast majority of specimens (actin, 86%; FN, 95%; GFAP, 96%), although the extent of staining varied for each. Actin-FN co-localization was observed in all diagnostic groups on comparison of adjacent sections and in double-labeled sections. The extent of actin staining did not correlate with clinical grading of PRM contraction. In PDR membranes, FN staining was low overall, but proportional to the vascular content of the PRM. Fibronectin staining of PVR membranes was greater, and extensive even in avascular specimens. In MP membranes, most cells were GFAP-positive, whereas in PDR and PVR specimens, GFAP staining was variable. The lack of correlation of clinical contractility and membrane composition, as studied in this article by immunostaining, indicates that other factors must play significant roles in determining membrane behavior.

Diagnosis and pathogenesis of retinal pigment epithelial tears

Ten cases of retinal pigment epithelial tears were observed in eight patients with serous pigment epithelial detachments associated with age-related macular degeneration. Eight of the ten tears were spontaneous and all occurred at the detachment margin. The resulting area of exposed choroid was sometimes initially mistaken for pigment epithelial atrophy. In two cases it was misdiagnosed as choroidal neovascularization and treated with laser photocoagulation. All but two patients suffered severe visual loss.

Laser treatment in fellow eyes with large drusen: Updated findings from a pilot randomized clinical trial

PURPOSE To update the findings from the Choroidal Neovascularization Prevention Trial (CNVPT) with respect to resolution of drusen, incidence of choroidal neovascularization, and visual function. DESIGN A multicenter, randomized, controlled, pilot clinical trial. PARTICIPANTS The 120 patients enrolled in the CNVPT. Patients had signs of choroidal neovascularization or retinal pigment epithelial detachment in 1 eye and had >/=10 large (>63- micro m) drusen in the contralateral, or fellow, eye. INTERVENTION The fellow eye of 59 patients was assigned randomly to argon green laser treatment consisting of multiple 100- micro m spots at least 750 micro m from the center of the fovea. The fellow eye of the remaining 61 patients was assigned randomly to observation. MAIN OUTCOME MEASURES Change in visual acuity was the primary outcome measure. Incidence of choroidal neovascularization, resolution of drusen, change in contrast threshold, change in critical print size for reading, and incidence of geographic atrophy were secondary outcome measures. RESULTS Throughout 4 years of follow-up, there were no statistically significant differences in change in visual acuity, contrast threshold, critical print size, or incidence of geographic atrophy. With additional follow-up, the large increase in the incidence of choroidal neovascularization observed within 18 months of treatment was maintained; however, by 30 months, the incidence in the two treatment groups was the same. Most drusen resolution in treated eyes occurred within 24 months of the initial treatment. Treated eyes that received higher-intensity laser burns had an increased risk of choroidal neovascularization. Among eyes developing choroidal neovascularization in each treatment group, most lesions (two thirds or more) were composed of occult neovascularization only. CONCLUSIONS Laser treatment as applied in the CNVPT caused an excess risk of choroidal neovascularization in the first year or so after treatment. The increased early incidence of choroidal neovascularization was not associated with either a harmful or beneficial effect in this pilot study.

Immunocytochemical study of an eye with proliferative vitreoretinopathy and retinal tacks.

After an eye-wall resection for a choroidal melanoma, a 32-year-old woman had subsequent retinal detachment with proliferative vitreoretinopathy (PVR), and an unsuccessful attempt at repair with retinal tacks. Gross and light-microscopic examination of the globe revealed a total retinal detachment with extensive preretinal and subretinal membranes. The membranes surrounded the tack heads and extended in taut bands to form a tractional detachment of the pars plana. The membranes contained glial and nonglial cells. The glial cells immunolabeled for glial fibrillary acidic protein (GFAP), carbonic anhydrase-C (CA-C), vimentin, and glutamine synthetase (GS), thus suggesting that they were Müllers cells. While the tacks did not seem to cause PVR, in this case they may have provided an anchoring point from which membranes were able to exert traction on the retina and pars plana.

Normal EOG Values of Young Subjects

Electro-oculograms were recorded from fifty normal subjects between fifteen and thirty years of age, 25 males and 25 females. Refractive error distributions were the same in both sex groups. Average EOG ratio for the male subjects was 2.28, for the females 2.49; this difference was statistically significant. Twenty subjects were retested on another day to establish limits on the intersession variability of the tests. 95% of the eyes retested were found to have an intersession variability of less than 0.6.