Association of Predominantly Peripheral Diabetic Retinopathy Lesions (PPL) with Oximetry-Measured Retinal Ischemia and Nonperfusion on Ultrawide Field Angiography

Abstract

Purpose : To evaluate the association of PPL in diabetic retinopathy (DR) with markers of retinal ischemia measured using retinal oximetry and retinal nonperfusion (NP) on ultrawide field fluorescein angiography (UWF-FA).

Methods : ETDRS retinopathy severity and presence of PPL were evaluated using stereoscopic UWF images. Retinal oximetry (Oxymap ehf., Reykjavik, Iceland) and UWF-FA images were obtained at the same visit. Retinal NP (mm²) was measured from phase-plate adjusted stereographically projected UWF-FA images by a masked grader at a centralized reading center. Venous oxygen saturation (VO₂, mmHg) and arteriovenous difference (A-V, mmHg) for each subject were calculated within a 2-disc diameter ring centered on the optic disc.

Results : 46 eyes of 23 patients were studied. Demographics: mean age 41.0±10.3 yrs, diabetes duration 21.1±10.7 yrs, HbA1c 7.7%±1.0, 65.2% (15) male and 73.9% (17) type 1 diabetes. DR severity based on UWF images was: no DR 9.1% (2), mild nonproliferative DR (NPDR) 43.2% (19), moderate 20.4% (9), severe 9.1% (4), active proliferative DR (PDR) 13.6% (6), and quiescent PDR (QPDR) 4.6% (2). Mean NP (mm2) on UWF-FA was associated with increasing DR severity: no DR (35.2); mild (99.7), moderate (130.9), severe (133.5) NPDR; and active PDR (327.6) (p=0.001). NP area decreased to levels similar to no DR in the 2 eyes with QPDR (p=NS). The association between NP and DR severity remained after correction for diabetes duration and HbA1c (p=0.002). PPL were more common with increasing DR severity (no DR: 0%; mild: 47.4%, moderate: 77.8%, severe: 50% NPDR; active PDR: 100%, p=0.012). Presence of PPL was associated with increasing NP & VO2, and decreasing A-V (PPL: NP= 178, VO2=71.2, A- V=25.7; No PPL: NP= 87.7, VO2=68.3, A-V=29.4; NP p=0.048, VO2 p=0.001, A-V p=0.014), remaining significant after correcting for HbA1c, DM duration and DR severity (NP p=0.035, VO2 p=0.018, A-V p=0.012).

Conclusions : In this cohort, PPL were associated with increased NP, increased VO₂ and decreased A-V, suggesting greater areas of retinal ischemia, presence of venous shunting and/or reduced retinal oxygen consumption. Past studies have shown that presence of PPL increases DR progression. These data suggest that the underlying reason PPL are associated with DR progression may be increased NP and retinal ischemia.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.