Type-3 macular neovascularization in a case of long-standing macular telangiectasia type-2

We report a rare case of type-3 macular neovascularization (MNV) in an established case of macular telangiectasia type-2 (MacTel). A 49-year-old healthy Indian woman was diagnosed with MacTel (Gass and Blodi stage 3 in the right eye [OD] and stage 2 in the left eye [OS]) in our retina clinic in January 2004. She was subsequently seen 10 years later with MacTel progression in OD (stage 4) and drusenoid changes in both eyes. She recently complained of sudden onset diminution of vision in OS of 1 week duration. The best-corrected visual acuity, when she attended this day, was 20/500 (OD) and 20/60 (OS). Fundus revealed pigment deposition in the macula in OD and a large pigment epithelial detachment (PED) in OS with drusen in both eyes, suggesting coexisting age macular degeneration (AMD) and MacTel (stage 4 OD; stage 2 OS) bilaterally. Multimodal imaging with spectral-domain optical coherence tomography showed drusen, a large trapezoid PED with central apical disruption, outer retinal hyperreflective material, intraretinal fluid, and inner retinal cavitation. Indocyanine green angiography revealed "hotspot" at center of the PED with hairpin-loop vessels. Optical coherence tomography angiography demonstrated network at apex of the PED. These features confirmed a diagnosis of type-3 MNV (classical retinal angiomatous proliferation [RAP] lesion) in OS along with features of AMD and MacTel. There was resolution of intraretinal fluid and reduction in height of PED following three loading doses of intravitreal ranibizumab in OS. Although type-3 neovascularization has been described in MacTel, to the best of our knowledge, this is the first documentation of classical RAP features of MNV with all described multimodal imaging features. The type-3 neovascularization typically described in association with MacTel is retinal-retinal, retinal-subretinal, and retinochoroidal anastomosis (RCA). Although RAP is also associated with RCA, the features seen in our case, i.e., triad of erosion at the roof of PED, inverted flap in the PED, and hotspot in the center of PED, have not been documented in association with MacTel.