LAUSR

OBJECTIVE Early detection and treatment can prevent irreversible blindness from diabetic retinopathy (DR), which is the leading cause of visual impairment among working-aged adults worldwide. 80% of affected persons live in low- and middle-income countries, yet, lack of resources has largely prevented DR screening implementation in these world regions. Smartphone-based fundus imaging (SBFI) allows for low-cost mobile fundus examination using an adapter on a smartphone, however, key aspects such as image quality, diagnostic accuracy and comparability of different approaches have not been systematically assessed to date. DESIGN Evaluation of diagnostic technology PARTICIPANTS: Three hundred and eighty one eyes of 193 patients with diabetes were recruited at outreach eye clinics in South-India. METHODS We compared four technically different approaches of SBFI (three approaches based on direct and one approach based on indirect ophthalmoscopy) in terms of image quality and diagnostic accuracy for DR screening. MAIN OUTCOME MEASURES Image quality (sharpness, reflex artifacts, contrast and illumination), field-of-view, examination time, and diagnostic accuracy for DR screening were analyzed against conventional fundus photography and clinical examination. RESULTS SBFI based on indirect ophthalmoscopy yielded the best image quality (p<0.01), the largest field-of-view, and the longest examination time (111 vs. 68 - 86 seconds, p<0.0001). Agreement with the reference standard (Cohen's kappa 0.868) and sensitivity/specificity to detect DR were highest for the indirect SBFI approach (0.79/0.99 for any and 1.0/1.0 for severe DR, 0.79/1.0 for diabetic maculopathy). CONCLUSIONS SBFI can meet DR screening requirements in an outreach setting, however, not all devices are suitable in terms of image quality and diagnostic accuracy. SBFI might aid in alleviating the burden of DR screening in low- and middle-income countries and these results will allow for a better selection of SBFI devices in field trials for DR screening.