Coats' Disease in Children: A Review of Clinical Manifestat
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Coats' disease is idiopathic childhood eye disease characterized by retinal telangiectasia and aneurysmal changes in the retinal vessels. The telangiectactic vessels may lead to intraretinal and subretinal exudation. It is resulted from defect during development of retinal vascularization. The incidence of Coats’ disease is reported as minimum as 0.09% per 100,000. The course of the disease depends primarily on age at onset. It usually begins at age 3-4 months and progress rapidly. About 60-70% cases of Coats’ disease present in the first or second decades of life, with average age of diagnosis between 8 -16 years.

Coats’ disease is caused by mutation of Norrie disease protein (NDP) gene, CRB1, and PANK2. NDP gene mutation results in deficiency of norrin, an essential protein for normal vasculogenesis in retina. CRB1 is a transmembrane protein presents in brain and retina. As CRB1 gene mutation is also involved in other exudative retinopathies, Coats’ disease has been associated with several conditions including Senior-Loken syndrome, Turner syndrome, and Hallermann-Streiff syndrome.

Younger children are often present with strabismus or leukocoria, whereas older children are most likely to present with unilateral decreased vision. Most patients with Coat's disease have significant poor vision, varying from 20/20 to no perception of light. The presence of subfoveal exudates, subfoveal fibrosis, or hemorrhage, macular edema, epiretinal membrane, and optic atrophy contribute to poor vision in Coats’ disease. Other symptoms that can be present includes eye pain, heterochromia of the iris, squinting, xanthocoria, and glaucoma. The severity of the disease are related to age of presentation. Previous studies show that younger patients had worse presenting visual acquity and more advanced stage of Coats’ disease.

The gold standard for clinical diagnosis of Coats’ disease, as well as staging of the disease, is examination of fundus by indirect ophtalmoscopy. Ultrasonography is used to evaluate posterior segment that can be limited due to media opacity or poor patient cooperation. It can also be used to confirm the degree of the disease. USG demonstrates the presence and extent of retinal detachment and retinal elevation, as well as subretinal opacities as a result of cholesterolosis from the exudates. (CT) examination in Coats’ disease exhibits thickening in the ipsilateral eye wall with crescent-shaped & “V”-shaped high-density areas behind the vitreous. In advanced Coat's disease, CT reveals hyperdense area of lipid exudates within the orbit and retinal detachment. CT is particularly useful in ruling out retinoblastoma which has similar clinical picture with cases of advanced Coats’ disease.

The choice of treatment for patients with Coats’ disease varies depending on the stage of the disease. If the condition is mild and not vision-threatening, patients should be observed periodically. Patients with stage 2 to stage 3A of Coats’ disease, cryotherapy or laser photocoagulation is generally performed. Surgery is recommended for patients with retinal detachment (stage 3A or higher), whereas enucleation is preferred in patients with stage 4 and severe eye pain. Patients with stage 5 of Coats’ disease are observed, as they typically had very poor visual acquity with no hope for return of vision.

Coats’ disease is a disease of the retina that affects children, especially boys. At an advanced stage this disease can cause blindness. The challenge faced is a difficult initial diagnosis, because the child is not yet aware of the visual complaints in one eye. Therefore, periodic eye examinations in children needs to be done.Coats’ disease has several similarities with other diseases, one of which is retinoblastoma.