Purpose: To elucidate outer-retinal choroidal microvascular abnormalities (ORCMA) observed in Macular Telangiectasia type 2 (MacTel 2), particularly in association with outer retina-associated hyperreflectivity (ORaH).
Methods: Retrospective analysis of 60 eyes with MacTel 2 having ORaH was conducted. OCT and OCTA images were meticulously reviewed to identify ORCMA patterns.
Results: All 60 eyes exhibited hyperreflective foci (HRF), with varying incidences of subsidence, ellipsoid zone (EZ) loss, pigment clumps, cystoids, and double-layer sign (DLS). Vascular invasion, retinochoroidal anastomosis (RCA), and macular neovascularization (MNV) were observed, with all cases demonstrating ORaH. OCTA revealed microvascular changes. Subsidence correlated significantly with invasion (P=0.009), while pigment clumps, cystoids, and DLS were not significant. RCA was associated with pigment clumps, cystoids, and DLS (P<0.05), whereas MNV correlated with subsidence (P=0.022).
Conclusion: The study delineates ORCMA in MacTel 2, identifying three patterns: vascular invasion, RCA, and MNV. Vascular invasion affects the outer retina, potentially leading to subsidence. RCA, a pre-proliferative stage, involves anastomosis between retinal and choroidal microvasculature, associated with pigment clumps, cystoids, and DLS. MNV, an advanced stage, exhibits extensions below the RPE and exudation, suggesting a continuum from invasion to neovascularization. Recognizing these stages aids in diagnosis, prognosis, and intervention development for MacTel 2.