Onset and clinical features


The onset of symptoms generally appears in the first decade of life and the mean age of onset is 5 years. Less common adult form with onset after the age of 35 years has also been described.

Clinical features

The classic "childhood/adolescent" form of Coats disease is isolated, unilateral and almost invariably seen in males. The typical presenting signs include blurred vision, unilateral decreased vision (visual acuity of 20/200 or worse), strabismus and/or leucocoria. Deterioration in either central or peripheral vision is the main symptom. Photopsia and floaters are common. Persistent color patterns may also be perceived.
Often, the unaffected eye compensates for the loss of vision in the other eye; however, this may result in some loss of depth perception and parallax.

The hallmark of the disease is the development of telangiectasia in the retinal periphery which can lead to massive subretinal exudation and retinal detachment. In more than 50 % of cases, the telangiectasias are found anterior to the equator, with predilection for the temporal and inferior quadrants. In addition to telangiectasis, there may be capillary nonperfusion, aneurysmal formation, and massive lipid deposition.

At advanced stages, retinal detachment is likely to occur. Secondary cataracts can also develop. The natural history is variable but typically progressive. Patients who develop extensive exudative retinal detachment commonly progress to total retinal detachment, neovascular glaucoma, and phthisis bulbi. It seems that the earlier age of presentation correlates with more severe disease course and progression. The presenting visual acuity also correlates with the long-term prognosis. Risk factors predictive of poor visual outcome include postequatorial, diffuse, or superior location of the telangiectasias and exudation, failed resolution of subretinal fluid after treatment, and presence of retinal macrocysts.

In rare cases, Coats disease can bee initially diagnosed in adulthood, with clinical manifestations similar to those diagnosed in childhood. These patients are often asymptomatic or present with good vision, and did not have leukocoria, extensive areas of exudation, or retinal detachment.
In adult patients, vascular abnormalities appeared in the equatorial and peripheral regions in all the patients and also in the juxtamacular region in the vast majority. Adult-onset cases are frequently associated with elevated serum cholesterol and generally have slower disease progression.

Coats disease is isolated in the majority of cases, although associations with facioscapulohumeral muscular dystrophy, Senior-Loken syndrome and multiple glomus tumors have been described.