Diagnostic accuracy of non-mydriatic fundus camera for screening of diabetic retinopathy: A hospital based observational study in Pakistan.

Objective: To determine the diagnostic accuracy of non-mydriatic fundus camera for the detection of diabetic retinopathy.
Methods: The cross-sectional study was conducted at Al Ibrahim Eye Hospital, Karachi, from January to May 2015, and comprised patients with type 2 diabetes who were screened for diabetic retinopathy. Single 45° fundus image focussed at macula was obtained and labelled using non-mydriatic fundus camera by a trained optometrist. Photos were labelled as positive (diabetic retinopathy present), negative (no diabetic retinopathy) or unreadable. The pupil was then dilated and fundi were examined by ophthalmologist with slit-lamp and fundus lens. Results of fundus examination were labelled as positive, negative or invisible/indecisive. Results of ophthalmologist were taken as the standard reference to evaluate sensitivity and speci?city for detecting diabetic retinopathy with non-mydriatic fundus camera. SPSS 20 was used for data analysis.
Results: Total eyes screened numbered 2970 related to 1485 patients. Diabetic retinopathy was found in 646(21.8%) eyes, 485(20.9%) photographs were unreadable and 1839(57.3%) were normal. Ophthalmologist on slit lamp bio-microscopy labelled 736(25%) eyes as positive for diabetes retinopathy, 335(15%) as indecisive and 1899(60%) as normal. The sensitivity of non-mydriatic fundus camera was 400/556 (72%) while specificity was 1548/1794 (86.3%). Positive predictive value and negative predictive value were 400/646 (62%) and 1548/1704 (90%) respectively. The level of agreement was moderate (k=0.0551) for optometrist compared to ophthalmologist. False positive diagnosis by optometrist numbered 78/1839 (4.24%) and false negative was 123/646(19%).
Conclusions: Non-mydriatic fundus camera was found to be a reliable screening tool for detecting and referral diabetic retinopathy cases to ophthalmologist for further evaluation and management.