OCT Reflectance and Fluorescein Angiographic Intensity in Patients with Uveitic Disc Edema

Abstract

Purpose : Optic disc edema (ODE) can accompany uveitis, an entity we term Uveitic Disc Edema (UDE). Disc leakage on fluorescein angiography (FA) and retinal thickening at the disc on optical coherence tomography (OCT) are features of disc edema, but these changes have not been directly studied in UDE. We conducted a retrospective imaging analysis of 32 eyes from 18 adults with UDE. We hypothesized that disc thickness would correlate inversely with mean retinal reflectance and directly with disc leakage on FA.

Methods : All subjects were evaluated by a single uveitis specialist. Inclusion criteria were diagnosis of uveitis and ODE with OCT disc raster and FA performed at the same visit. Central OCT cross-sections and FA images were imported into ImageJ for analysis. Disc thickness was estimated with line measurement at the region of maximum retinal height. The retinal perimeter was traced, and reflectance was calculated as the mean pixel intensity in this subregion. Similarly, the perimeter of the optic disc was traced in FA images from the recirculation phase (10 min) and fluorescence was measured as mean pixel intensity in this region.

Results : Eighteen adults (9M, 9F) met inclusion criteria. Diagnoses included anterior (3), intermediate (4), posterior uveitis (1), panuveitis (3), multifocal choroiditis (2), isolated ODE (1), and retinal vasculitis (4). Mean retinal thickness was 756.18 ± 242.86 µm. Mean retinal reflectance was 114.00 ± 13.37 au. Mean disc fluorescence was 161.5 ± 32.65 au. Regression analyses revealed inverse correlation between retinal reflectance and thickness (p<0.0001; r²=0.430). Disc fluorescence did not correlate with retinal thickness or reflectance.

Conclusions : Disc thickness correlated inversely with mean reflectance on OCT disc raster, likely due to decreased density of reflective tissue elements corresponding to heightened inflammation. Surprisingly, neither disc thickness nor mean reflectance correlated with optic disc fluorescence on FA. Our results suggest that in UDE, FA intensity does not necessarily relate to severity of disc thickening.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

OCT (A, B) and FA (C, D) images from subjects with low (C) and high (D) disc fluorescence despite similar retinal thickness. Orange lines show disc thickness measurement.

 

Disc thickness shows a significant negative correlation with retinal reflectance (A). Disc fluorescence did not correlate with retinal reflectance (B) or disc thickness (C).