A small number of older type 2 diabetic patients end up visually impaired despite regular photographic screening and laser treatment for diabetic retinopathy

Abstract

Purpose: The present study describes the prevalence of visual impairment and blindness in a geographically defined population 8 years after the introduction of a screening programme in 1987 for early detection of sight-threatening diabetic retinopathy. Methods: Of 374 patients with diabetes, comprising 2.6% of the population in the study community, 72% were examined with fundus photography or biomicroscopy during 1994-95. These patients form the basis of this study. The screening programme was fulfilled by 93% of subjects, all of whom underwent ophthalmic examinations at least every other year. A total of 79 eyes in 52 patients received photocoagulation for macular oedema alone or in combination with severe non-proliferative or proliferative retinopathy. Results: Eight years after the implementation of the programme, only three patients, all with type 2 diabetes (diabetes diagnosed at or after 30 years of age), had visual acuity ≤0.1. The total number of eyes with visual acuity ≤0.5 was higher in insulin-treated type 2 diabetic patients (n = 20) than in those on oral treatment (n = 5) or diet treatment only (n = 1) (p=0.006 in both cases). The only independent risk factor for visual impairment in eyes with sight-threatening retinopathy was age. Conclusion: A small number of older type 2 diabetic patients end up with visual impairment due to unsuccessful photocoagulation of macular oedema.