Global Connections to Study Idiopathic Macular Telangiectasia Type 2
This group of investigators has collaborated since 2005 by conducting the largest observational longitudinal study of Mac Tel Type 2 to date.2–5 This project has evolved over the decade with strong interactions and collaboration between the clinicians from 31 international clinical sites and investigators from a dozen basic science laboratories located in the United States, Europe, and Australia. Mac Tel type 2 characteristic lesions include retinal opacification, perifoveal telangiectatic vessels that leak on fluorescein angiography, right angle vessels and crystalline deposits (Figure). With more advanced disease, retinal pigment epithelial hyperpigmentation occurs, quite often along the right-angle vessels. Abnormalities are seen on fundus autofluorescence imaging, as well as on spectral domain optical coherence tomography, where hypo-reflective inner and outer retinal cavities, as well as ellipsoid zone or inner segment/outer segment losses, are found. Macular pigment loss is also evident. Less frequently, neovascularization originating from the retinal circulation can occur, forming retinal-choroidal anastomoses.
The MacTel research group has also made significant efforts to study genetic, high resolution imaging, and metabolomics. In addition, significant efforts are ongoing to study genetic, high resolution imaging, and metabolomics related to Mac Tel Type 2. This condition, once thought be vascular in origin, is now considered a neuro/vasculo/glial degenerative disease. This concept is supported by clinical data from in vivo adaptive optics imaging6 and studies of autopsy eyes from patients with Mac Tel Type 2.7,8 More recently, genetic and metabolomic studies suggest that MacTel may have a genetic/metabolic component with a defect in serine/glycine metabolism.9
This clinical research group followed a cohort of affected individuals in a natural history study and completed both Phase 110 and Phase 2 clinical trials in Mac Tel Type 2 using a ciliary neurotrophic factor implant.