Possible choroidal neovascularization in macular telangiectasia type 2

Purpose: To use volume-rendered optical coherence tomography angiography to investigate vascular proliferation in macular telangiectasia type 2 (MacTel2), extending beyond the retinal pigment epithelium (RPE). Methods: Six eyes of four patients with MacTel2 with neovascularization proliferating external to the RPE confines were studied. Eyes were scanned using optical coherence tomography using split-spectrum amplitude-decorrelation techniques to derive flow information (RTVue XR; Optovue). These data were extracted and used to create volume rendered images of the area of vascular proliferation. Results: Mean age was 66.2 years. There was demonstrable vascular proliferation in the sub-RPE space observable by both optical coherence tomography and optical coherence tomography angiography. Fibrovascular RPE detachments were identified in all eyes. The topographic distribution of abnormal vessels located below the plane of the deep retinal vascular plexus and above the RPE closely matched the pattern of hyperfluorescence and leakage on fluorescein angiography. Vessels under the RPE demonstrated different branching patterns and larger diameter lumens than those above the RPE, but anastomosis with the choroidal circulation was difficult to demonstrate. Conclusion: This study provides evidence that sub-RPE vascular proliferation may be a complication of MacTel2. Retinal pigment epithelium abnormalities are known to occur in MacTel2 and may provide a conduit for abnormal vessels in the subretinal space to proliferate into the sub-RPE compartment. The authors have no reason to exclude the possibility that the choroid contributes to the deep proliferation.