Coats disease is characterized by the presence of vascular dilatations (retinal telangiectasia), including ectatic arterioles, microaneurysms, venous dilations (phlebectasias), and fusiform capillary dilatations, which are frequently associated with exudative retinal detachment. Usually only 1 eye is involved, and there is a marked male predominance (85%). To date, researchers have not identified an associated gene or chromosome or any hereditary pattern, and no association between Coats disease and systemic disease has been found.
In an eye with Coats disease, the abnormal vessels are compromised, resulting in the leakage of serum and other blood components, which accumulate in and under the retina. Any portion of the peripheral and macular capillary system may be involved. Although angiography demonstrates the presence of retinal capillary nonperfusion, posterior segment neovascularization is unusual. The clinical findings vary widely, ranging from mild retinal vascular abnormalities and minimal exudation to extensive areas of retinal telangiectasia associated with massive leakage and exudative retinal detachment. The severity and rate of progression appear greater in children under the age of 4 years, in whom massive exudative retinal detachment with the retina apposed to the lens may simulate retinoblastoma or other causes of leukocoria (called Coats reaction; Fig 7-8; also see BCSC Section 6, Pediatric Ophthalmology and Strabismus, for the differential diagnosis of leukocoria) or xanthocoria (yellow pupil).
Figure 7-8 Coats disease. A, Ultra-wide-field fundus photograph of a patient with Coats disease showing dilated vessels with aneurysmal changes in the inferior temporal periphery as well as moderate to severe accumulation of exudate in the macula. B, Corresponding fluorescein angiography image shows nonperfusion in the peripheral retina and around the abnormal blood vessels. The aneurysms, characteristic of Coats disease, hyperfluoresce brightly and leak.
(Courtesy of Colin A. McCannel, MD.)
Patients with peripheral areas of leaky vascular anomalies typically present with lipid deposition in an otherwise angiographically normal macula, because “hard” exudate tends to accumulate in the macula. Similar findings in adults probably represent late decompensation of preexisting vascular anomalies. Occasionally, the initial finding is a submacular lipogranuloma or subretinal fibrosis. The differential diagnosis for Coats disease may include
dominant (familial) exudative vitreoretinopathy
facioscapulohumeral muscular dystrophy
retinopathy of prematurity (ROP)
retinal hemangioblastomas (von Hippel–Lindau syndrome)
For milder cases of lipid exudation, additional considerations are diabetic retinopathy, BRVO, juxtafoveal retinal telangiectasia, and radiation retinopathy.
Treatment of Coats disease generally consists of ablation with photocoagulation or cryotherapy, and, in severe cases, retinal reattachment surgery. Photocoagulation and cryotherapy are effective in obliterating the vascular anomalies and in halting progression. Several treatments may be necessary, and long-term follow-up is important to detect and treat recurrences or disease progression. Intravitreal anti–vascular endothelial growth factor (VEGF) therapy may be a useful adjunctive treatment that is resistant to ablative therapy alone.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.