GENESIS OF RETINAL–CHOROIDAL ANASTOMOSIS IN MACULAR TELANGIECTASIA TYPE 2

PURPOSE To longitudinally characterize structural/angiographic findings of retinal-choroidal anastomosis (RCA) in macular telangiectasia Type 2 (MacTel2). METHODS A combined retrospective/prospective review of patients with MacTel2 with >2 visits and >2 months follow-up, including examination, fundus photography, fluorescein angiography, spectral-domain optical coherence tomography, and projection-resolved optical coherence tomography angiography. RESULTS There were 24 eyes of 12 patients with a mean age of 61.1 (±7.3 [SD]) years and median follow-up of 447 (range 81-1,511) days. There were five eyes diagnosed with new RCA after not having any previously. Retinal-choroidal anastomosis was diagnosed in 8 (33%) eyes initially and eventually 13 (54%). In the eight eyes initially diagnosed with RCA, the number of RCAs and outer retinal hyperrflective lesions increased over the follow-up. The RCAs were found in clusters, generally temporal to the fovea. Retinal-choroidal anastomosis was uniformly associated with complete retinal subsidence, defined as the loss of outer nuclear layer substance such that the middle retinal layers sank down toward the retinal pigment epithelium (RPE), and was also present in each case. Each RCA colocalized with a region of hyperreflectivity, previously termed an outer retinal hyperreflective lesion. There was a lack of fluorescein leakage, lipid, hemorrhage, or any structural correlates with fluid exudation, and no signs of subretinal/subretinal pigment epithelium neovascularization. CONCLUSION De novo RCA development seems to be associated with retinal subsidence, and after RCAs form, they increase in number and topographic distribution over time. Initially after formation, there was no sign of exudation. These data suggest the descent of the deep capillary plexus occurs with RCA, devoid of subretinal/subretinal pigment epithelium neovascularization in MacTel2.