Macular Telangiectasia Type II
SALIENT FEATURES
Bilateral, slowly progressive condition usually affecting patients between the ages of 40 and 60 years characterized by macular capillary changes, variable foveal cavitations, and loss of outer retinal structure with eventual macular atrophy.1
Muller cell dysfunction and the corresponding photoreceptor loss may be attributable to systemically low serine levels; abnormal serine metabolism results in elevated deoxysphingolipids, which may be associated with macular toxicity as a result of the neurotoxic effects of the metabolite deoxydihydroceramide produced from the hydrolyzation of deoxysphingolipids.2
Hallmarks of the disease include unique zone of “light gray discoloration” in the temporal juxtafoveal macula due to the loss of retinal transparency,3 presence of telangiectatic macular vessels, retinal pigment epithelial (RPE) hypertrophy, blunted “right-angle” venules, crystalline deposits, and pigmentary migration into the retina.1
Potential complications of the disease include proliferation of pigment plaques, photoreceptor loss, foveal atrophy, and subretinal neovascularization temporal to the fovea that may result in visual loss from hemorrhage or exudation.4
Fluorescein angiography is the historical gold standard to confirm the diagnosis of the disease showing telangiectatic capillaries, most commonly temporal to the foveola, in the early phase and a diffuse hyperfluorescence in the late phase (late hyperfluorescence may even be noted in the absence of telangiectatic alterations, Figure 15.1).4
FIGURE 15.1 Early (A) and late (B) fluorescein angiography showing telangieactatic capillaries that leak late in the temporal portions of the macula. Corresponding fundus photo (C). Optical coherence tomography (OCT) (D) shows focal outer retinal loss and ellipsoid zone attenuation. Optical coherence tomography angiography (OCTA) of the superficial (E), deep (F), and whole retina (G) highlights the temporal telangiectatic vessels. Corresponding OCTs demonstrate degenerative cystic changes.
Lipid exudates, intra- or subretinal hemorrhage, and macular edema are not typical features of this disease and warrant reconsideration for diagnosis and staging.1
OCT IMAGING
Characteristic features on spectral-domain OCT (SD-OCT) include macular thinning, plaques and breaks in the ellipsoid zone with progressive outer retinal atrophy, temporal foveal pit enlargement that may progress into large hyporeflective cavitations in the inner and outer retina, and the development of full-thickness macular hole in the absence of vitreoretinal traction.5
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