Three conditions involve retinal telangiectasia: Leber’s miliary aneurysm, Coats’ disease and idiopathic juxtafoveal telangiectasia. Each occurs due to abnormal retinal capillaries. Coats’ disease and Leber’s miliary aneurysm share a similar appearance and origin, they may be different forms of the same disease.
Leber’s miliary aneurysm involves an aneurysm and telangiectasia in the retinal periphery. It’s more common in males, and is typically discovered in the first decade of life. In Leber’s, the vessels remain patent with minimal leakage.
When the telangiectatic vessels lead to extensive leakage and exudation, the condition is diagnosed as Coats’ disease. A growth hormone may stimulate these changes, which may explain why most Coats’ disease cases are diagnosed in the first two decades of life. 43.
In Coats’ disease cystic cavities develop in response to a breakdown in the blood–retinal barrier due to the telangiectasis. These cystic cavities fill with proteins and lipids on and below the retina. There’s also a macrophage response, with lipids migrating deep within the retina. This brings subretinal accumulation of exudates and a retinal detachment.
Retinal edema may also be persistent, causing decreased acuity when it reaches the macula. Ischemia may develop as well, with neovascularization and subsequent vitreal hemorrhage and retinal detachment.
Leber’s miliary aneurysm calls for periodic monitoring. Coats’ disease, if left unchecked, will lead to total retinal detachment. Treatment consists of laser photocoagulation or cryoretinopexy to destroy the abnormal vessels, as well as scleral buckling to repair any retinal detachment.
Idiopathic juxtafoveal retinal telangiectasia (IJRT) is not associated with Leber’s miliary aneurysm or Coats’ disease, but may be a variation of the same disease process. IJRT, which is more benign than Coats’ disease, involves a capillary malformation at the edge of the foveal avascular zone. 44.
IJRT may be unilateral or bilateral. The unilateral form only affects men, and typically is not discovered until after age 40–44 Patients with unilateral IJRT are usually asymptomatic. However, leakage may cause macular edema and reduced visual acuity. Fundus assessment often reveals parafoveal dot and blot hemorrhages and, rarely, exudates.
Bilateral IJRT affects women as well as men, typically between ages 40 and 60. The presentation is often symmetrical, and involves retinal edema, parafoveal hemorrhaging, RPE hyperplasia and possibly choroidal neovascularization. Despite these changes, vision tends to be 20/30 or better.