Optical Coherence Tomography Angiography of Macular Telangiectasia Type 2.

Macular telangiectasia type 2 (MacTel2) is a disease of the central macula that affects all microvascular layers of the retina and also includes neovascularization arising from both the retinal and choroidal circulations. As a result, MacTel2 is the ideal macular disease for imaging with optical coherence tomography (OCT) angiography (OCTA). In MacTel2, the earliest changes in the retinal microvasculature involve the temporal aspect of the parafoveal deep capillary plexus, and OCTA reveals these changes. Microvascular abnormalities then extend circumferentially around the fovea and into the superficial capillary plexus. As the disease progresses, dilated anastomoses form between the superficial and deep capillary plexuses, and the retina becomes more atrophic, with the formation of cysts and the loss of photoreceptor outer segments. In some patients, the anastomoses between the plexuses progress to subretinal neovascularization, with connections to the choroidal vasculature. OCTA provides clear advantages over current imaging modalities, such as traditional OCT imaging, reflectance fundus imaging, autofluorescence imaging, fluorescein angiography, and indocyanine green angiography, for MacTel2 because it is safer, cheaper, more comfortable for the patient, and more easily repeatable, it can be performed during follow-up visits, and it produces both intensity-based OCT images and flow-based images, which allow for visualization of the macular microvasculature. OCTA is the only imaging modality needed for the diagnosis and monitoring of MacTel2 at every stage of disease progression.