Sensitivity and specificity of digital retinal images in grading diabetic retinopathy

Abstract

Purpose: To assess three novel digital fundus cameras for diabetic retinopathy (DR) screening.

Methods: Digital colour and red-free retinal imaging (Topcon TRC 50 IA, Canon CR6-45NM, and MediTell) was used to capture 427 images of 70 diabetes patients and control subjects. The images were graded for DR by three readers in a randomized and masked manner using a modified Early Treatment Diabetic Retinopathy Study classification. The reference standard was based on mydriatic ophthalmoscopy and colour and red-free images.

Results: Digital 50 degrees red-free imaging had sensitivity of 97.7%, two-field 50 degrees colour imaging 94.0%, and two-field 45 degrees colour imaging sensitivity of 88.9%. The specificity of these imaging modalities was 98.9-100%, and ungradeable images represented 1.2-1.6%. The hand-held digital colour videocamera (MediTell) showed a sensitivity of 6.9% and ungradeable images represented 92.3%.

Conclusion: Digital 50 degrees red-free and two-field 50 degrees or 45 degrees colour imaging were suitable for DR screening, whereas the hand-held digital videocamera did not fulfil the needs of DR screening.