Distribution of Nonperfusion Area on Ultra Widefield Angiography in Eyes with Diabetic Macular Edema: DAVE Study

Abstract

Purpose : To explore the relationship between distribution of nonperfusion area (NPA) on ultra widefield angiography (UWFA) and the severity of diabetic macular edema (DME).

Methods : The DAVE study (NCT01552408) is a prospective, randomized clinical trial of patients with DME aimed at comparing the efficacy and safety of ranibizumab monotherapy versus combination therapy of ranibizumab with UWFA-guided retinal photocoagulation targeted to areas of capillary non-perfusion. UWFA images were sent to the Doheny Image Reading Center where they were montaged and corrected using a stereographic projection method to adjust for peripheral image distortion. A mid-phase fovea-centered FA frame was selected for each case at baseline, and the NPA was manually segmented by two experienced, independent/masked certified graders using a previously reported standardized protocol. Both the NPA and total visible retinal area (TRA) were computed in mm². The ischemic index (ISI) was then calculated by dividing the NPA by the TRA. The distribution of NPA (and ISI) were also assessed within concentric rings centered on the fovea in 3 pre-specified zones (by radius): posterior zone (<10 mm), mid-peripheral ring (10-15 mm), and far periphery (>15 mm of the fovea). Baseline NPA and ISI within these zones was correlated with baseline central macular thickness (CMT) and macular volume (MV) on optical coherence tomography (OCT).

Results : 40 eyes from 29 patients with treatment naïve DME were included in this analysis. Mean age was 55.8 years and at baseline, mean visual acuity (VA) was 59.6 EDTRS letters, with a mean CMT of 536.9 µm and mean MV of 11.9 mm³. VA was correlated with CMT (R=0.39, p=0.008) and MV (R=0.42, p=0.004). The distribution of NPA was: posterior zone, 63.9 mm² (32.6% of total NPA); mid-periphery, 93.5 mm² (47.7%), and far periphery, 38.8 mm² (19.7%). The distribution of ISI was: posterior zone, 0.22; mid-periphery, 0.37; and far periphery, 0.43. The NPA and ISI among the three retinal zones were significantly different (NPA: p<0.001; ISI: p=0.005). The global NPA and ISI for the entire retina were not associated with CMT or MV. The NPA and ISI in the mid peripheral zone, however, were associated with CMT (NPA: p=0.04; ISI: p=0.02).

Conclusions : In eyes with DME, the ISI increases with increasing distance from the fovea. The severity of DME appears to be most related to ischemia in the mid-periphery.

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