Screening for diabetic retinopathy in primary care: Retinal photography alone can be used efficiently and effectively to exclude those with sight threatening lesions

Abstract

Background - Good screening performance of retinal photography and ophthalmoscopy together in screening for diabetic retinopathy in primary care have been reported. This study reanalysed the data to evaluate the screening performance of photography alone. Methods - One thousand and ten patients screened by fundal photography and ophthalmoscopy were studied retrospectively. Fundal photographs were quality graded with poor quality pictures being excluded from the analysis. Each patient was reviewed initially by both retinal photographs and ophthalmoscopy by an ophthalmologist, the 'gold standard'. Six months later the fundal photographs were reviewed and reported in a blinded manner by the ophthalmologist. Results - Two thousand and fourteen photographs were obtained, of which 162 (8%) had to be excluded because of poor quality. On review of the remaining 1852 photographs in isolation, of 77 cases of severe retinopathy as determined by the 'gold standard', 67 had severe changes on photography- detection rate 87%. Of the 1775 cases without sight threatening retinopathy only five were judged to have sight threatening changes on photography-false positive rate 0.3%. Considering sight threatening and background retinopathy together, the detection rate was 69% (257 of 375) and the false positive rate 1.6% (23 of 1477). Conclusion - Good quality fundal photographs alone seem specific enough to screen for sight threatening diabetic retinopathy, but will underdetect background retinopathy.