Coats disease is defined by the presence of vascular dilatations (retinal telangiectasia), including ectatic arterioles, microaneurysms, venous dilations (phlebectasias), and fusiform capillary dilatations, frequently associated with exudative retinal detachment. Despite the presence of retinal capillary nonperfusion shown by angiography, posterior segment neovascularization is distinctly unusual. The abnormal vessels are incompetent, 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. Variation in the clinical findings is wide, ranging from mild retinal vascular abnormalities and minimal exudation to extensive areas of retinal telangiectasia associated with massive leakage and exudative retinal detachment, as may be seen in children presenting with leukocoria (Coats reaction; Fig 5-48).
This retinal condition is not hereditary and is not associated with systemic vascular abnormalities, even though a gene has been located on chromosome 4. Entities such as retinitis pigmentosa and others may occasionally be associated with retinal telangiectasia. Usually only 1 eye is involved, and there is a marked male predominance (85%). Gradual progression with increasing exudation occurs over time. The severity and rate of progression appear greater in patients under the age of 4 years, in whom massive exudative retinal detachment with retina apposed to the lens may simulate retinoblastoma. Therefore, Coats disease is included in the differential diagnosis of leukocoria (apart from Coats disease, the differential diagnosis for leukocoria in this age group includes retinoblastoma, retinoma, retinal dysplasia, coloboma, myelinated nerve fibers, astrocytic hamartoma, granuloma, persistent fetal vasculature [PFV], trauma, endophthalmitis, incontinentia pigmenti, ROP, FEVR, and Norrie disease). BCSC Section 4, Ophthalmic Pathology and Intraocular Tumors, discusses retinoblastoma in depth.
Patients with peripheral areas of leaky vascular anomalies typically present with lipid deposition in an otherwise angiographically normal macula, as hard exudate tends to accumulate in the macula. Similar findings seen in adults probably represent late decompensation of preexisting vascular anomalies. Occasionally, a submacular lipogranuloma or subretinal fibrosis is the initial finding. The differential diagnosis may include
dominant (familial) exudative vitreoretinopathy
facioscapulohumeral muscular dystrophy
capillary hemangioma (von Hippel)
For milder cases of lipid exudation, diabetic retinopathy, BRVO, juxtafoveal retinal telangiectasia, and radiation retinopathy may be considered.
Treatment of Coats disease generally consists of photocoagulation, cryotherapy, and, in severe cases, retinal reattachment surgery. Photocoagulation and cryotherapy are effective in obliterating the vascular anomalies and in halting progression. Multiple treatments may be necessary, and long-term follow-up is important to detect recurrences.
, ShieldsJA, BrownGC, TasmanW. Coats’ disease: evaluation of management.1982;89:1381–1387.