The preproliferative stage in type 2 macular telangiectasia (MacTel type 2)

To study clinical and imaging features of various stages of macular telangiectasia (MacTel type 2).

In this retrospective study, cases of MacTel type 2 with fluorescein angiography (FA), optical coherence tomography (OCT) and OCT-angiography (OCTA) imaging were included. Based on angiographic perifoveal fluorescence, two groups were formed: group 1: diffuse hyperfluoroscence and group 2: diffuse + focal hyperfluoroscence. Later, based on OCT features, group 2 was subdivided into group 2A: without SRNVM and group 2B: with SRNVM. Clinical, FA, OCT and OCTA features were analysed. Eyes showing conversion to the proliferative stage at final visit were noted.

Ninety-four eyes of 48 patients were included. Group 1 (n = 28) showed diffuse perifoveal hyperfluoroscence, hyperreflective middle retinal layers, absent SRNVM (p = 0.006) on OCT and dilated perifoveal capillaries in deep capillary plexus (DCP) on OCTA. Group 2A (n = 40) showed diffuse + focal perifoveal hyperfluoroscence, hyperreflective middle retinal layers (p = 0.001), hyporeflective outer retina cavities (p = 0.021), absent SRNVM with dilated and bunching perifoveal capillaries (p = 0.004) in DCP. Group 2B (n = 26) showed late diffuse + focal perifoveal hyperfluoroscence, foveal contour irregularity (p = 0.002), retinal pigment clumps (p = 0.015) and SRNVM on OCT with bunching of capillaries in DCP and vessels in outer retina (p = 0.002). Five eyes showed conversion to group 2B at final visit.

There exists a distinct disease stage called "preproliferative" MacTel type 2 showing clinical features of non-proliferative disease, diffuse + focal perifoveal hyperfluoroscence on FA, absent SRNVM on OCT and bunching perifoveal capillaries in DCP on OCTA. Its identification is important for suspecting proliferative disease, planning management and follow-up visit accordingly.