Abstract
Purpose: :
Grade R2 is referable non-proliferative retinopathy in the ENSPDR. R2 approximately encompasses levels 43 to 53E of the modified Arlie House Grading Classification. We aimed to investigate whether sub-grading of referred R2 images based on intra retinal microvascular anomalies (irma) would correlate with clinical outcomes at 1 year.
Methods: :
From a single ENSPDR programme of 20.000 registered diabetic patients 200 (100 unilateral and 100 bilateral) R2 were identified prospectively from consecutive R2 referrals in 2009/10. Image sets from one randomly selected eye of bilateral (B) and all unilateral (U) eyes were sub-graded in masked fashion using a 5 point scale based on extent of irma (irma-only 1-3) and additional pre-proliferative features (irma-plus 4-5) by an accredited senior grader. Clinical outcomes at 1 year or nearest subsequent visit (12 - 17m post screening photographs) were traced using eye clinic electronic records and ENSPDR database. Fisher’s exact test was used to calculate significance.
Results: :
Outcomes were unknown for 38 (19%) eyes at 1 year because of death (5 total:4B,1U) and non-attendance (33:20B,13U). Of 162 eyes 18 (11%) had developed proliferative retinopathy (R3). R3 was more common in bilateral (13 of 76) than unilateral (5 of 86) eyes, p=0.03. A further 28 eyes (17%) were treated for FFA-confirmed retinal ischaemia (R2P) and were more frequent in bilateral (16 of 76) than unilateral R2 (12 of 86) but did not reach significance p=0.3. Nineteen eyes (12%) had lower grade retinopathy (R1) at 1 year, bilateral R2 (2 of 76) had significantly fewer than unilateral (17 of 86) p<0.01. Furthermore sub-grading of baseline image sets correlated with grade outcomes. Irma-plus sub-grades (4-5 59% total) identified 16 of 18 (88%) R3 and 25 of 28 (89%) R2P. Irma-only sub-grades (1-3 41% total) were allocated to 18 of 19 (95%) R1. All three results were significant p<0.01.
Conclusions: :
Randomly chosen eyes from bilateral R2 retinopathy have significantly more proliferative and significantly less background retinopathy at one year than unilateral R2 eyes. This may be a reflection of systemic disease. Unilateral R2 had progressed to ischaemia in 20% eyes at 1 year and referral is still warranted. Our study found that by stratifying baseline images for irma +/- other features we identified likely grade outcomes at 1 year. If this result is confirmed by others it may indicate that less intensive monitoring of irma-only R2 could be used in ENSPDR.
Keywords: diabetic retinopathy • imaging/image analysis: clinical • ischemia