Comparison of 2-Field and 5-Field Mydriatic Handheld Retinal Imaging in a Community-Based Diabetic Retinopathy Screening Program

Abstract

Purpose : To compare 2-field (2F) and 5-field (5F) mydriatic handheld retinal imaging for the assessment of diabetic retinopathy (DR) in a community-based teleophthalmology DR screening program (DRSP)

Methods : Following a validated standard imaging protocol, 5F imaging [macula, disc, superior, inferior and temporal] was acquired using a handheld retinal camera (Aurora, Optomed plc) through dilated pupils. 2F (disc and macula) and 5F images were independently assessed by masked graders using the International DR classification at a centralized reading center. Simple (K) and weighted (Kw) kappa statistics were derived for DR/DME. Sensitivity and specificity for referable DR [refDR (moderate nonproliferative DR (NPDR) or worse or ungradable images] and vision threatening DR [(vtDR) severe NPDR or worse] for 2F compared to 5F imaging were calculated.

Results : Images of 805 eyes from 407 consecutive patients with diabetes from a community-based teleophthalmology DRSP were evaluated. Distribution of DR severity by 2F/5F images (%): no DR 66.0/61.7, mild NPDR 10.7/14.4, moderate NPDR 7.9/8.1, severe NPDR 3.3/5.6, PDR 5.6/4.6, ungradable 6.5/5.6. Table 1 presents the cross-tabulation of DR severity by 2F and 5F with ungradable eyes excluded from the analysis. Exact agreement of DR grading between 2F and 5F photos was 81.7%, within 1-step 97.1%, K 0.64, Kw 0.78. Sensitivity/specificity for 2F compared 5F was refDR 0.80/0.97, vtDR 0.73/0.98. Figure 1 presents a sample comparison of 2F and 5F images. The rate of ungradable images with 2F was 16.1% higher than with 5F (6.5% vs 5.6%).

Conclusions : Mydriatic 2F and 5F handheld imaging have substantial agreement for DR severity grading. Mydriatic 2F handheld imaging achieves the sensitivity and specificity thresholds (0.80/0.95) for refDR (0.80/0.97) but not for vtDR (0.73/0.98) suggesting that lower thresholds for referral must be used when using 2F handheld imaging in a community-based teleophthalmology DRSP. Without the addition of peripheral fields included in 5F handheld imaging, the sensitivity threshold when using vtDR for referrals will not be achieved and would limit its use in DRSP.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Table 1. Cross-tabulation of DR severity between 2F and 5F Handheld Retinal Imaging

 

Figure 1. Comparison of 2F and 5F handheld retinal images