Abstract
PURPOSE: To evaluate the association of baseline ellipsoid zone (EZ) parameters on optical coherence tomography (OCT) as calculated by a semi-automated computer algorithm with baseline visual acuity in eyes with retinal vein occlusion (RVO). DESIGN: Retrospective consecutive case series. SUBJECTS: Patients affected by RVO presenting from January 2011 to December 2014. METHODS: Baseline demographics, clinical characteristics, and SD-OCT data at presentation were collected. Macular cube scans were exported into a retinal layer analysis software platform and outer retinal parameters were evaluated. Outer retinal/EZ parameters included EZ-retinal pigment epithelium (RPE) volume, central foveal EZ-RPE area, EZ-RPE central subfield thickness (CST), and EZ-RPE central foveal thickness (CFT). In addition, en face EZ mapping features were extracted including percent area with EZ attenuation (i.e., EZ-RPE thickness < 20 μm) and percent area with total EZ loss (i.e., EZ-RPE thickness = 0 μm). MAIN OUTCOME MEASURE: Correlation of EZ parameters and baseline visual acuity (VA). Secondary outcome measures: Correlation of EZ parameters with other clinical characteristics and OCT measures of cube volume, cube average thickness, central subfield thickness. RESULTS: One hundred and twelve eyes were included in this analysis. Mean baseline VA was 56.53 ±17.68 ETDRS letters and was inversely associated with total EZ loss and EZ-RPE attenuation (r= - 0.33 and -0.38 respectively, p<0.001). VA was directly associated with all other EZ parameters (r=0.37 to 0.45, p<0.001). The presence of subretinal fluid was strongly linked to central parameters of central foveal EZ-RPE, EZ-RPE-CST, and EZ-RPE-CFT (Kruskal-Wallis test). Conventional OCT parameters (central subfield retinal thickness, cube volume and cube average thickness) did not have significant correlations with EZ measures (-0.30.05). CONCLUSION: Baseline EZ integrity is closely linked to presenting visual acuity in eyes with RVO and macular edema. EZ mapping provides an additional metric for evaluating RVO impact on retinal anatomy and potential function.