Original Articles
Causes of severe visual loss in the early treatment diabetic retinopathy study: ETDRS report no. 24

https://doi.org/10.1016/S0002-9394(98)00309-2Get rights and content

Abstract

PURPOSE: To describe the causes of and risk factors for persistent severe visual loss occurring in the Early Treatment Diabetic Retinopathy Study (ETDRS).

METHODS: The ETDRS was a randomized clinical trial investigating photocoagulation and aspirin in 3,711 persons with mild to severe nonproliferative or early proliferative diabetic retinopathy. Severe visual loss, defined as best-corrected visual acuity of less than 5/200 on at least two consecutive 4-month follow-up visits, developed in 257 eyes (219 persons). Of these 257 eyes, 149 (127 persons) did not recover to 5/200 or better at any visit (persistent severe visual loss). Ocular characteristics of these eyes were compared with those of eyes with severe visual loss that improved to 5/200 or better at any subsequent visit. Characteristics of patients with severe visual loss that did and did not improve and those without severe visual loss were also compared.

RESULTS: Severe visual loss that persisted developed in 149 eyes of 127 persons. In order of decreasing frequency, reasons recorded for persistent visual loss included vitreous or preretinal hemorrhage, macular edema or macular pigmentary changes related to macular edema, macular or retinal detachment, and neovascular glaucoma. Compared with all patients without persistent severe visual loss, patients with persistent severe visual loss had higher mean levels of hemoglobin A1c (10.4% vs 9.7%; P = .001) and higher levels of cholesterol (244.1 vs 228.5 mg/dl; P = .0081) at baseline. Otherwise, patients with persistent severe visual loss were similar to patients with severe visual loss that improved and to those without severe visual loss.

CONCLUSIONS: Persistent severe visual loss was an infrequent occurrence in the ETDRS. Its leading cause was vitreous or preretinal hemorrhage, followed by macular edema or macular pigmentary changes related to macular edema and retinal detachment. The low frequency of persistent severe visual loss in the ETDRS is most likely related to the nearly universal intervention with scatter photocoagulation (either before or soon after high-risk proliferative diabetic retinopathy developed) and the intervention with vitreous surgery when clinically indicated.

Section snippets

Patients and methods

From April 1980 to July 1985, the ETDRS enrolled 3,711 patients with diabetes whose eyes met the following criteria: (1) no macular edema, visual acuity of 20/40 or better, and moderate or severe nonproliferative diabetic retinopathy or early proliferative diabetic retinopathy, or (2) macular edema, visual acuity of 20/200 or better, and mild, moderate, or severe nonproliferative or early proliferative diabetic retinopathy. Patients with favorable prognosis for survival and follow-up for at

Results

A total of 257 eyes (219 persons) developed severe visual loss. In 149 eyes (127 persons), severe visual loss persisted, and in 91, visual acuity improved. Seventeen of the 257 eyes with severe visual loss had insufficient follow-up and were not included in our analysis (Table 1). The Figure 1 shows the distribution of visual acuity 1 to 5 years after the first occurrence of visual acuity less than 5/200. After the occurrence of severe visual loss, about one third of eyes recovered to 5/200 or

Discussion

Vitreous or preretinal hemorrhage was the most common cause of severe visual loss in the ETDRS, accounting for 125 of 240 eyes. Perhaps surprisingly, no recovery from severe visual loss was observed in 61 of these 125 eyes. One explanation for persistence of severe visual loss in these eyes may be coexistent disease in addition to the hemorrhage. Review of fundus photographs by one of us (D.S.F.) showed that 17 (27.9%) of these 61 eyes harbored a coexistent retinal detachment and three

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