35.1 Features
The Macular Telangiectasia Project proposed the classification of several retinal telangiectatic disorders into two distinct groups, now termed macular telangiectasia type 1 and type 2. Macular telangiectasia type 1 is considered a unilateral disorder characterized by aneurysms, lipid exudation, and retinal ischemia, but typically no neovascularization. This chapter will focus on the more commonly encountered macular telangiectasia type 2 (MacTel 2), an idiopathic, bilateral disorder that manifests in the fifth or sixth decade of life as neurosensory retinal atrophy and ectatic capillaries in the macula. Gass and Blodi staging represents chronological changes seen on fundus exam and fluorescein angiography in MacTel 2 (or Idiopathic Juxtafoveolar Retinal Telangiectasis Group 2A, as they termed it; ▶ Table 35.1). In addition, MacTel 2 has also been described based on the presence of neovascularization: a non-proliferative stage characterized by atrophy and a proliferative stage marked by neovascularization. The prevalence of 0.02 to 0.1% for MacTel 2 reported in studies from the United States, Australia, and Africa is based solely on grading of color fundus photographs and likely underestimates the true prevalence. A slight predilection toward women, 64% in the Mac Tel Project, was shown. Known systemic associations include diabetes and hypertension. A genetic link is suspected, given bilaterality and autosomal dominant pattern of inheritance, but the relationship is likely polygenic as no single causative gene has been identified.
Stage 1 | No changes on ophthalmoscopy; minimal capillary dilation and mild late staining of the outer retina temporally on fluorescein angiography |
Stage 2 | Perifoveolar graying and minimal telangiectasia on ophthalmoscopy; evidence of capillary telangiectasia temporal to the fovea on fluorescein angiography |
Stage 3 | Dilated, blunted venule(s) diving at right angle on ophthalmoscopy; permeability changes underlying right angle venules on fluorescein angiography |
Stage 4 | Retinal pigment epithelium hyperplasia in proximity to right angle venule(s) |
Stage 5 | Subretinal neovascularization |
35.1.1 Common Symptoms
Slow loss of vision, distorted vision, trouble reading, and scotomata are some symptoms.
35.1.2 Exam Findings
Parafoveal retinal graying or loss of transparency, ectatic capillaries, and inner retinal crystalline deposits thought to be Müller cell footplates encompass an oval area around the fovea, but are invariably more predominant temporally. Dilated venules with blunt ends dive at right angles (e.g., right angle venules) toward the deeper retina in the fovea and are associated with retinal pigment epithelium (RPE) hypertrophy and pigment migration into the retina (▶ Fig. 35.1).
Fig. 35.1 Fundus photograph in MacTel 2 demonstrating parafoveal graying, telangiectatic vessels, and inner retinal crystalline deposits. Retinal pigment epithelium migration is visualized along a right angle dilated venule diving into the deep retina.
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