Two-field photography can identify patients with vision-threatening diabetic retinopathy: a screening approach in the primary care setting.

Abstract

To compare the effectiveness of two 45 degrees photographic fields per eye in the screening for diabetic retinopathy with the routine ophthalmologist's examination and to study the effectiveness of visual acuity measurement in the detection of diabetic macular edema. Type 1 and 2 diabetic patients without a known history of more than minimal retinopathy (n = 469) had a routine examination by an ophthalmologist, including visual acuity measurement, indirect retinoscopy, and biomicroscopy. At the same time, two-field nonstereoscopic retinal photographs were made of both eyes and assessed in a masked fashion by a retinal specialist. The results were compared. The prevalence was 4.3% for vision-threatening retinopathy and 24% for any retinopathy. The sensitivity of two-field photography in identifying diabetic patients with sight-threatening retinopathy was 95% (specificity 99%) and sensitivity for detecting any retinopathy was 83% (specificity 88%). The percentage of referrals to an ophthalmologist was 6.2%. All patients with macular edema detected by biomicroscopy were classified as having vision-threatening retinopathy on the photographs. Two-field retinal photography is a promising alternative to the routine ophthalmologist's examination in the screening for diabetic retinopathy. Visual acuity measurement is not a sensitive tool for the detection of macular edema. Screening for diabetic retinopathy using two-field retinal photography is feasible in a primary care setting and can substantially lower the number of ophthalmic referrals.