Abstract
Purpose :
To compare three different devices for direct and one for indirect smartphone-based fundus imaging (SBFI) regarding image quality and sensitivity/specificity to detect diabetic retinopathy (DR) in a real-world setting in South-India.
Methods :
412 eyes from 206 patients with diabetes were clinically examined and imaged following a modified seven-fields-imaging protocol with SBFI in video mode using the direct SBFI devices Peek Retina (Peek Vision Ltd, UK), the D-Eye adapter (D-EYE S.r.l., Italy) and a do-it-yourself solution developed by the Sankara Eye Foundation, the indirect SBFI device Paxos Scope (Verana Health, USA) as well as conventional color-fundus-photography (CFP, 3nethra royal, Forus Health, India). Semi-quantitative scales for image quality regarding sharpness, reflex artifacts and illumination were developed. Image quality, examination time and sensitivity/specificity to detect severe DR (stage 3/4), any DR and macular involvement were compared between the devices and the gold standard (CFP).
Results :
1445 videos (35 hours of total video material) and 1800 single images were analyzed. The field-of-view was smaller in direct compared to indirect SBFI. There was no difference in sharpness between direct and indirect SBFI (p=0.46), reflex artifacts were less frequently observed in indirect compared to direct SBFI (p<0.001), and illumination was better in indirect SBFI (p<0.001). Examination took longer in indirect SBFI (77.8±40.0 vs. 111.6±62.1 seconds, p<0.001). Sensitivity/specificity to detect severe DR were 56%/100% for direct and 100%/99% for indirect devices, respectively. Sensitivity/specificity to detect any DR were 62.6%/93.9% for direct and 72.3%/100% for indirect devices. For detection of macular involvement sensitivity/specificity were 59%/94% for direct and 79%/100% for indirect devices.
Conclusions :
There are significant differences between direct and indirect devices for SBFI in terms of image quality and sensitivity/specificity to detect DR. Smaller retinal hemorrhages and exudates are detectable more reliably in direct SBFI due to a higher magnification, however image quality, field-of-view and overall sensitivity/specificity are superior in indirect SBFI compared to gold standard CFP.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.