Macular telangiectasia type 2 (MacTel2) is an uncommon, bilateral, and asymmetric condition that typically presents between the ages of 40 and 60 years without sex predilection.1-9 Its estimated prevalence ranges from 0.02 to 0.10%.2,8 The disease can manifest in either a nonproliferative or proliferative phase; the latter is far less common. The etiology of MacTel2 is poorly understood, but it is believed to have neurodegenerative as well as vascular components.1-6,8-10 We present a case of MacTel2 and highlight the role of diagnostic imaging in early diagnosis prior to development of classic funduscopic features.
Case Presentation
A 66-year-old White male with a 10-year history of type 2 diabetes mellitus (T2DM) presented to the eye clinic for an annual eye examination. The patient was taking metformin, and 6 months prior to presentation, his hemoglobin A1c was 7.4%. He had a history of mild nonproliferative diabetic retinopathy in the left eye without diabetic macular edema. He reported no ocular concerns.
On examination, best-corrected visual acuity (VA) was 20/20 in each eye. Slit-lamp examination was notable only for bilateral mild nuclear sclerosis. Dilated fundus examination showed a blunted foveal reflex consistent with the appearance of a macular pseudo-hole in the right eye and was unremarkable in the left eye (Figure 1).
Macular optical coherence tomography (OCT) revealed an intraretinal cyst without thickening in the temporal fovea of both eyes with mild disruption of the underlying ellipsoid zone in the right eye (Figure 2). A presumptive diagnosis of MacTel2 vs diabetic macular edema was made, and the patient was referred to the retina clinic for further evaluation.
At the 1-month follow-up in the retina clinic, VA, macula OCT, and fundus examination were stable. Fundus autofluorescence (FAF), optical coherence tomography angiography (OCT-A), and fluorescein angiography (FA) were performed. The FAF revealed a hyperreflective crescent in the temporal aspect of the fovea of both eyes, greater in the right eye than the left (Figure 3). The OCT-A showed abnormal dilation of the vessels in the deep capillary plexus of the temporal fovea of both eyes (Figure 4). This area of abnormality correlated to the area of hyperreflectivity seen on FAF. The early- phase FA revealed telangiectatic vessels in the temporal fovea in both eyes; in the late phase, there was leakage of telangiectatic vessels, which remained localized to the temporal perifovea and spared the central fovea of both eyes (Figure 5). The patient was diagnosed with MacTel2.
Discussion
This case highlights several important management considerations in MacTel2. These include symptoms, disease stage, and diagnostic imaging, which can allow more precise staging of the disease.
The etiology of MacTel2 is unknown.6 It is believed to be primarily a neurodegenerative condition that damages Müller cells and photoreceptors, leading to vascular changes.1-6,8-10 Müller cells may play a role in creating and maintaining the integrity of the blood-retinal barrier, particularly in the deep capillary plexus where the vascular abnormalities begin.6,10 These early changes in the deep capillary plexus may evolve to include the superficial capillary plexus in intermediate stages with anastomoses forming between the 2 layers.2,6-10 Late proliferative stages show significant alterations of the juxtafoveal capillary network, subretinal neovascularization and retinochoroidal anastomoses.6,7,9,11 In one cohort study, 81% of patients with MacTel2 were White, and a genetic link is still under investigation.2,4-9
Presentation
The most common symptoms of MacTel2 include blurred vision, microscotoma, metamorphopsia, and difficulty reading, with missing or distorted letters a common concern.1,2,4-8 Best-corrected VA at presentation is usually better than 20/30, and disease progression tends to be slow.2,6 Microscotomata are best mapped with microperimetry.1-3,5-7
