Does size of telangiectasia on optical coherence tomography angiography influence vision in eyes with type 2 macular telangiectasia?

Purpose: To study the influence of dimensions of macular telangiectasia (MacTel) on enface optical coherence tomography angiography (OCTA) on vision and clinical parameters in eyes with MacTel type 2. Methods: MacTel was classified based on OCTA location, i.e. either temporal to the fovea (grade 1), or spread nasally (grade 2), or circumferentially (grade 3), or the presence of neovascular-like tissue in the outer retina-choriocapillary complex (ORCC) (grade 4). On enface images, the maximum dimensions of the MacTel in the deep plexus were noted using calipers by a single experienced observer. Results: Ninety-eight eyes of 49 patients with MacTel with a mean visual acuity was 0.46 + 0.26 logMAR and mean macular thickness of 202 +/- 132 mu were included. Based on OCTA, grade 3 MacTel (n = 35, 36%) was the commonest followed by grade 4 (n = 28, 29%). The mean maximum vertical diameter of the MacTel was 2019 + 753 mu, and every 500 microns increment in vertical diameter of the MacTel was associated with a half-line drop in vision (95%CI = 0.005 to 0.08 logMAR, P = 0.03). Vision gradually reduced with increment in OCTA grades of MacTel from grade 1 to 3; however, the trend was not maintained in grade 4 MacTel, which showed better vision and lesser degenerative cysts. Conclusion: Larger telangiectasias were associated with significantly lower vision in MacTel. Eyes with deeper telangiectasia involving ORCC have better vision and evidence of far lesser neurodegeneration than type 3 disease, suggesting that this may not be part of the continuum and does not represent neovascularization.