Early detection and treatment can prevent irreversible blindness from diabetic retinopathy (DR), which is the leading cause of visual impairment among working-age adults worldwide. Its prevalence continues to rise alarmingly, most markedly in middle-income countries where the cost of care and limited access to eye specialists are the major barriers to sufficient eye care. Smartphone-based fundus imaging (SBFI) allows for low-cost mobile fundus examination using an adapter on a smartphone.
Four different SBFI devices in terms of various image quality criteria, field-of-view, examination time, and diagnostic accuracy to detect DR in outreach eye clinics in South-India were compared. SBFI based on indirect ophthalmoscopy yielded the best image quality, the largest field-of-view, and the longest examination time (111 vs. 68 - 86 seconds,). 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)
In conclusion, study demonstrates that SBFI may be a feasible approach for screening of treatment-requiring DR in low-resources settings. However, there are marked differences between the SBFI devices employed here regarding image quality and diagnostic accuracy. SBFI might have the potential to alleviate the burden of DR screening in low- and middle-income countries. However, agreement on standard SBFI imaging protocols, image quality scales and more studies on its integration into service provision appear prudent..