Functional Relevance of Hyper-Reflectivity in Macular Telangiectasia Type 2.

Purpose: The purpose of this study was to quantify hyper-reflective lesions on en face optical coherence tomography (OCT) and study its functional relevance in macular telangiectasia type 2 (MacTel). Design: This was a retrospective, cross-sectional cohort study. Methods: Baseline image and functional data from participants of a phase II clinical trial (NCT01949324) that studied the effect of Ciliary Neurotrophic Factor in patients with MacTel were analyzed. The projection of hyper-reflectivity within different layers on OCT was used to generate an en face view and measure the en face size of hyper-reflectivity. Ellipsoid zone (EZ)-loss was additionally evaluated, and en face images were superimposed onto microperimetry sensitivity maps, allowing to estimate mean retinal sensitivity within areas displaying hyper-reflectivity and EZ-loss, respectively. Best-corrected visual acuity (BCVA) and reading speed were also analyzed. Results: Fifty-two eyes from 52 patients were analyzed. Hyper-reflectivity was present in 32 eyes (62%), and EZ-loss in 50 (96%) eyes. Mean lesion size was 0.11 mm² (range = 0.01-0.26) for hyper-reflectivity and 0.51 mm² (range = 0.02-1.34) for EZ-loss, and lesion sizes correlated strongly (Spearman r = 0.79, P < 0.001). Although both hyper-reflectivity and EZ-loss were associated with a significant decrease in retinal sensitivity, mean sensitivity thresholds differed significantly between lesions (0.9 dB vs. 16.3 dB; P < 0.001), indicating an almost complete loss of sensitivity in hyper-reflective areas. No correlations were found between the size of hyper-reflectivity and BCVA (r = 0.09) or reading speed (r = -0.17). Conclusions: En face OCT can be used to quantify the area of hyper-reflective lesions in MacTel. Hyper-reflectivity in MacTel is associated with severe functional impairment, leading to an almost complete loss of retinal sensitivity as observed on microperimetry.