Ellipsoid Zone Status and its Association with Visual Acuity in Eyes with Macular Edema in the Study of COmparative Treatments for REtinal Vein Occlusion 2 (SCORE 2)

Abstract

Purpose : To evaluate the status of the ellipsoid zone (EZ) assessed by spectral domain optical coherence tomography (SDOCT) and its association with visual acuity (VA) in eyes with macular edema secondary to central or hemiretinal vein occlusion in SCORE 2.

Methods : Heidelberg and Zeiss SDOCT macular cube scans of a randomly-selected subset of 75 study eyes stratified by baseline VA were converted to Digital Imaging and Communications in Medicine (DICOM) format and the EZ layer was segmented using custom software. Assessment of the EZ was not possible on baseline scans due to a >90% rate of ungradable images resulting from signal blockage by hemorrhage or fluid. At Month 1, 42 eyes were found to have gradable images and the scans from these eyes were graded at Months 1, 6 and 12. EZ layer thickness was measured within the central subfield (CSF) from the top of the EZ layer to the top of the retinal pigment epithelium (RPE). Using en face images within the macular cube, all EZ defects identified were classified as either involving or not involving the CSF, and the area of each EZ defect was quantified.

Results : In this subset of SCORE2 participants (n=42), the mean EZ thickness at Month 1 was 0.024mm (SD 0.0084) in the CSF. An area of EZ defect at Month 1 was present in 95.2% of eyes and the mean area of EZ defect was 1.613 mm² (SD 1.1910). Mean VA at Month 1 was 78.1 (SD 10.02) Early Treatment of Diabetic Retinopathy Study (ETDRS) letters in eyes with an area of EZ defect and no CSF involvement compared to 63.8 (SD 19.03) letters in eyes with CSF involvement (p < 0.001). There is a significant negative correlation between area of EZ defects at Month 1 and contemporaneous EZ thickness, and a significant positive correlation between EZ thickness and VA (p<0.0001). Larger area of EZ defects at Month 1 was associated with worse VA at Months 6 and 12.

Conclusions : At Month 1, thinner EZ and larger area of EZ defect were associated with worse VA in eyes with macular edema due to central or hemiretinal vein occlusion treated at baseline with anti-vascular endothelial growth factor therapy. There was no significant association between change in EZ thickness or change in area of EZ defect and change in VA from Month 1 to Month 6, however there was a significant correlation between change in EZ thickness and change in VA from Month 1 to Month 12.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.