Quantification of Retinal and Choriocapillaris Perfusion in Different Stages of Macular Telangiectasia Type 2

Abstract

Purpose: To quantify the retinal and choriocapillaris perfusion in different disease stages of macular telangiectasia type 2 (MacTel) using optical coherence tomography-angiography (OCT-A). Methods: We examined 76 eyes of 76 patients and 24 eyes of 24 age-related controls. Participants underwent multimodal imaging, including OCT and OCT-A. Patients' eyes were divided into three groups considering predefined criteria from funduscopy, OCT, and fluorescein angiography, thus reflecting the disease severity ("early," "advanced," and "neovascular"). Quantitative analyses of vessel density (VD), skeleton density (SD), and fractal dimension (FD) were conducted in the superficial and deep retinal plexus and in the avascular layer. The choriocapillaris was analyzed for mean signal intensity and percentage of nondetectable perfused choriocapillaris-area (PNPA). Results: The deep retinal plexus showed a progressive decrease of mean VD, SD, and FD in the temporal parafovea in all disease stages. In the superficial layer, VD, SD, and FD were significantly decreased in the temporal parafovea of advanced and neovascular stages, while these parameters did not differ from controls in early stages. In MacTel, signals of blood flow were also detectable at the level of the avascular layer and showed a significant increase with disease progression. The choriocapillaris in MacTel showed a significant increase of mean PNPA and a decrease of mean signal intensity in comparison to controls. These findings were consistent in all disease stages. Conclusions: Quantitative OCT-A data show a progressive rarefication of the retinal microvasculature in MacTel. We propose an altered choriocapillaris perfusion as a possibly early alteration of the disease.