RETINAL NONPERFUSION IN THE EARLY TREATMENT DIABETIC RETINOPATHY STUDY SEVEN FIELDS COMPARED WITH WIDEFIELD FLUORESCEIN ANGIOGRAPHY Correlation and Use of Extrapolation Factor

Background: In previous landmark studies on central retinal vein occlusion, retinal nonperfusion assessments were obtained using 7-field (7F) angiography. The widespread current use of widefield imaging allows better visualization of the peripheral retina and more comprehensive estimation of the total area of nonperfusion. The relationship between nonperfusion measurement of 7F and widefield angiography (WFA) in central retinal vein occlusion has not been studied. We aim to identify the correlation of retinal nonperfusion measured within the 7F and on WFA in eyes with central retinal vein occlusion. Methods: Retinal nonperfusion in participants with central retinal vein occlusion was determined using a 7F Early Treatment Diabetic Retinopathy Study template and the concentric rings method. Results: A total of 153 eyes were included. Pearson correlation test showed a near-perfect positive, linear correlation between the nonperfusion found in the 7F and total retinal nonperfusion on WFA (0.985 95% CI [0.793, 0.999]) The regression line equation for nonperfusion on 7F and WFA was y = 37 + 3.2x. Eyes with 0 disk areas (DA), >0 DA to 10 DA and >10 DA of nonperfusion on 7-fields had on average 23 DA 95% CI (19.20, 27.06), 45 DA 95% CI (35.75, 55.18), and 115 DA 95% CI (88.89, 142.05) on widefield respectively. Conclusion: There is a positive and linear relationship between nonperfusion measured by 7F and WFA in central retinal vein occlusion with more than 3-times the amount of nonperfusion identified on WFA. Despite <10 DA no areas of nonperfusion on 7F, there is typically at least 35 DA of nonperfusion on WFA whereas eyes with >10 DA of nonperfusion on 7F had at least 88 DA on WFA.