Abstract
Abstract: :
Purpose: The progress of visual acuity from time of identification of sight threatening diabetic retinopathy (STDR) in patients attending a systematic screening programme was examined. Methods: All patients with diabetes registered with enrolled general practices, excluding those concurrently attending an ophthalmologist, were invited for screening. Best VA was measured using 6m Snellen or 3.8m Bailey-logMAR charts. Patients in whom STDR was identified at screening (moderate preproliferative retinopathy or worse, circinate maculopathy or exudate within 1DD of foveal-centre) had ophthalmic follow-up. Visual impairment was defined as ≤20/80, partial-sight as ≤20/200 and blindness as ≤20/400 based on UK definitions. Results: Between 1991 and 2001, 11757 (926 type1, 10831 type 2) patients attended for screening. STDR was detected in 1045. Data were obtained for 92.5% (194 type 1- and 771 type 2). Cumulative incidences (95% confidence interval) were: visual impairment in better eye 1.1% (0.9-1.3) at 1 year and 1.9% (1.5-2.3) at 4 years, partial-sight and blindness 0% at 1 year rising to 1.4% (1.1-1.7) and 0.9% (0.7-1.1) respectively at 4 years, in type 1 diabetes; visual impairment in better eye 4.1%(3.8-4.4) at 1 year and 11.1%(9.6-12.6) at 4 years, partial-sight and blindness 1.2%(1.1-1.3) and 0.9%(0.8-1.0) in year 1 rising to 3.7%(3.2-4.2) and 2.5%(2.2-2.8) respectively in type 2 diabetes. STDR was the major/contributory cause in all type 1 patients with partial-sight / blindness, but in only 58.3% of blindness in type 2 patients. Visual impairment was significantly associated with the presence of clinically significant macular edema (CSME) at diagnosis of STDR in both groups. Conclusions: In a systematically screened population identified with STDR, a low incidence of visual impairment and blindness occurs in patients with type 1 diabetes, but remains high in patients with type 2 diabetes. STDR was the major cause of visual loss in both type 1 and type 2 diabetes, with other causes contributing significantly in patients with type 2 diabetes.
Keywords: clinical (human) or epidemiologic studies: pre • diabetic retinopathy • visual acuity