MACULAR TELANGIECTASIA TYPE 2: Acircularity Index and Quantitative Assessment of Foveal Avascular Zone Using Optical Coherence Tomography Angiography.

PURPOSE: The purpose of this study was to investigate the foveal avascular zone area and its perimeter, the acircularity index of the foveal avascular zone, the vessel density surrounding the foveal avascular zone, and the vessel density in the foveal, parafoveal, and perifoveal areas and their associations with best-corrected visual acuity, central foveal average thickness, and volume of ellipsoid zone-retinal pigment epithelium in patients with macular telangiectasia Type 2 (MacTel 2).

METHODS: We retrospectively reviewed medical records of 22 eyes of 22 patients with MacTel 2 and 24 eyes of 24 healthy controls. Eyes with MacTel 2 were graded according to optical coherence tomography angiography: 1) vascular anomalies temporal to the fovea; 2) vascular anomalies temporal and nasal to the fovea; 3) markedly diffuse circumferential vascular anomalies; and 4) neovascularization in the outer retina.

RESULTS: Acircularity index was higher and superficial-parafoveal vessel density was lower, in MacTel 2 group (all P < 0.05). Acircularity index was associated with the severity of the disease and had strong correlations with best-corrected visual acuity, ellipsoid zone-retinal pigment epithelium thickness, and ellipsoid zone-retinal pigment epithelium volume (all P < 0.05).

CONCLUSION: In conclusion, the increase in acircularity index is correlated with the severity of the disease, the decrease in ellipsoid zone-retinal pigment epithelium thickness and volume, and the decrease in best-corrected visual acuity. It may be used to monitor patients with MacTel 2.