Smartphone-based Nonmydriatic Fundus Imaging for Remote Glaucoma Screening

Abstract

Purpose : Screening for vision-threatening conditions represents a significant challenge to improving eye care in resource-constrained settings. The purpose of this study was to evaluate inter-rater agreement of glaucoma suspect status using a low-cost, handheld non-mydriatic fundus camera and to explore the impact of quantitative metrics including brightness, contrast, and focus on cup-to-disc ratio (CDR) grading.

Methods : Color fundus photographs were obtained using the PanOptic iExaminer attached to an iPhone 6S by a lay examiner on 206 participants in the Independent Nation of Samoa. Images were remotely graded by an ophthalmologist and optometrist and images from participants identified as at-risk for glaucoma were escalated to a glaucoma subspecialist for review. Fundus photo brightness, contrast, and focus were measured using the cup, rim, and temporal regions of the disc.

Results : Risk of glaucoma based on the original data set was identified in 16.0% of participants. There was moderately strong agreement between graders (90.3%) with k=0.53 (95% CI=0.33-0.73). The intra-class correlation coefficients for the cup-to-disc ratio and its difference were 0.84 (95% CI=0.81- 0.87) and 0.68 (95% CI=0.59-0.75). Of the 33 participants identified, fully 94% were confirmed as glaucoma suspects by a specialist. Color fundus photo cup brightness was significantly associated with CDR grade, R²= 0.36 (p<0.001) in which a brighter disc yielded a higher CDR. All participants with positive findings were referred for expedited review by a local ophthalmologist.

Conclusions : Features of glaucoma based on cupping of the optic disc were readily identified in individuals at risk for undiagnosed eye disease screened with the PanOptic iExaminer. Smartphone-based screening is a simple, low-cost method capable of reaching underserved patients outside of the traditional clinic.

This is a 2020 ARVO Annual Meeting abstract.