To determine if dilated smartphone photography with a 3D-printed adaptor for a fundus lens can be an alternative screening tool for diabetic retinopathy.

This was a single-center, prospective, comparative study of 102 eyes of patients with diabetes mellitus. DR screening was performed using binocular indirect ophthalmoscopy (BIO) as the reference standard, alongside two imaging modalities: a traditional fundus camera and a smartphone equipped with a 3D-printed adaptor. Coded images were evaluated by three masked retina specialists. Sensitivity, specificity, predictive values, and likelihood ratios were calculated for both imaging modalities.

DR gradings of both imaging modalities were compared to BIO and showed very good agreement (κ 0.94-0.96 95% CI 0.93-0.99). Both have high levels of interobserver reliability (kappa value 0.88-0.92 95% CI 0.84-0.96) and intraobserver reliability (kappa value 0.85-1.00 95% CI 0.64-1.00). Smartphone and Visucam 500 images can detect presence of DR with a sensitivity of 93.9% (95% CI 83.1-98.7) and 91.8% (95% CI 80.4- 97.7); and a specificity of 90.6% (95% CI 79.3-96.9) and 92.5% (95% CI 81.8-97.9), respectively, as well as the presence of vision threatening DR with a sensitivity of 100% (95% CI 91.2-100) and specificity of 85.5% (95% CI 74.2-93.1). Image quality was similar between the two imaging modalities (P=1.00).

Smartphone-based imaging with an attached 3D-printed adaptor offers high sensitivity and reliability comparable to a traditional fundus camera, and can be used an alternative for DR screening.