Coats Disease

A disorder characterized by idiopathic progressive, retinal telangiectasia with intraretinal and/or subretinal exudation. Possible association with renal dysfunction and cranial malformations.

Congenital Retinal Telangiectasia; Leber Miliary Aneurysm Disease; Exudative Retinitis.

A progressive congenital retinopathy first described by the Scottish ophthalmologist George Coats in 1908.

Unknown.

Coats disease is a sporadic, nonhereditary condition. Males are affected three times more often than females. No racial or ethnic predilection has been reported.

The retinal capillary endothelium is abnormally permeable. Affected vessels show a marked thickening of the basement membrane and widespread loss of endothelial cells and pericytes with subsequent disintegration of the blood-retinal barrier. The retinal protein norrin may be deficient or abnormal. There are retinal telangiectasias and aneurysms of the capillaries, venules, and arterioles. Lipoproteinaceous exudations are found in intraretinal and subretinal areas.

The age at onset has two peaks, one before 20 years of age and the second afterward. Most often, however, it is diagnosed at 7 to 10 years of age by the onset of retinal telangiectasias with intraretinal and/or subretinal exudation.

Coats disease is unilateral in more than 90% of cases and most frequently occurs in otherwise healthy patients. Bilateral occurrence is so rare that some researchers recommend questioning the diagnosis in these patients. The disease manifests as a deterioration in either central or peripheral vision. Rarely, Coats disease is associated with pathologic findings of the head and neck (microcephaly, intracranial calcifications, ataxia, depressed premaxillary region), the skin (absent scalp hair, syndactyly of fingers, dysplastic, grooved nails), and other ocular manifestations (paresis of ocular muscles, glaucoma). Renal impairment has been reported in some patients.

In cases of isolated Coats disease, no specific anesthetic precautions are required. However, if there is an association with extraocular manifestations, anesthetic care is influenced by the nature and severity of these features. Renal function may need to be assessed (electrolytes, serum creatinine, blood urea nitrogen). Check for difficult airway management.

Tracheal intubation can be difficult.

Renal dysfunction may affect elimination of drugs with predominantly renal excretion. Perioperative fluid regimen must be adapted to renal function. Avoid drugs that may increase intraocular pressure in the presence of glaucoma (e.g., atropine, succinylcholine).

Similar ocular features may be seen in retinitis pigmentosa, Alport Syndrome, Brachmann-de Lange Syndrome, Epidermal Nevus Syndrome, Hallermann-Streiff Syndrome, Landouzy-Dejerine Dystrophy, Loken Senior Syndrome, Ullrich-Turner Syndrome, aplastic anemia, and in renal transplant patients. However, the most important differential diagnosis in pediatric patients is Retinoblastoma, and failure to distinguish these two conditions will have serious consequences. Retinoblastoma usually is diagnosed at a younger age and does not have a sexual predilection. Retinoblastoma has a positive family history in approximately 10% and is bilateral in approximately 40% of patients, whereas Coats disease is unilateral in more than 90% of patients.