Coats disease

From EyeWiki

Coats disease
Classification and external resources
OMIM 300216
DiseasesDB 31162

Coats disease is a telangiectatic neovascular disease of the retina of unknown etiology that frequently affects unilateral eyes of young males.

Disease Entity

Coats disease is usually characterized by unilateral (90%), progressive development of abnormal vessels in the retina of the affected individuals. It’s more frequent in males (10:1) than females, and in patients younger than 8 years old, even though it has been observed in infants as well as older patients.


The disease is primarily due to aneurysmal and telangiectatic vessels as well as obstructed trichoid vessels. The usual location of these vessels is within the temporal retina. These abnormal vessels are leaky and there is exudation in various degrees.
No genetic basis has been found but there has been described chromosomal instability in chromosomes 3 and 13, as well as cases in patients with Turner Syndrome (XO), Senior Loken Syndrome and others.

Photo in courtesy of Dr Elias Feretis, MD, PhD, Hellenic Red Cross General Hospital, Ophthalmology Department, Athens, Greece


The etiology of the disease seems to be unknown, and there seems to be no clear predisposing factor. Nevertheless it is speculated that it’s due to anomalous leaking vessels. The leakage is caused by faulty endothelium, which in turn allows blood components to circulate in the retina and subretinally. This ends up in necrosis of the endothelium, abnormal neovascularization and telangiectasia.

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A montage of fundus image in a case of Coat's disease showing central and peripheral exudation.

Signs and Symptoms

Presenting symptom is frequently leukocoria but the diagnosis is determined fundoscopically. In mild cases one or two foci of retinal telangiectasia can be found usually on the temporal hemispheres. Microaneurysms, trichoidal obstruction and thickening of retinal venules are not uncommon, while it is possible that they are accompanied by retinal edema and exudates that may even obstruct the pathological vessels. The exudates vary in size and they have a tendency to occupy the inferior pole, as a result, visual acuity is reduced primarily due to infiltration of the fovea, formation of cystoid macular edema or even exudative retinal detachment. Those exudates ultimately cause discoid glial scarring and subretinal neo-vascularization, that can lead to glaucoma and phthisis.

Clinical diagnosis

Besides thorough fundoscopy, which ultimately establishes the diagnosis some clinical tests are utilized. The diagnostic tests to be used should include OCT, ultrasound and fluorescence angiography.


A very useful staging is the one developed by Comez-Morales and that of Siegelman.

Gomez- Morales Staging

Stage I: Focal exudates

Stage II: Massive exudation

Stage III: Partial exudative retinal detachment

Stage IV: Total Retinal Detachment

Stage V: Complications

Sigelman Staging

Stage I: Only telangiactasia

Stage II: Focal exudates

Stage III: Partial exudative retinal detachment

Stage IV: Total Retinal Detachment

Stage V: Complications

Differential diagnosis

The major clinical significance of Coats Disease is to differentiate it from Retinoblastoma since both appear with leukocoria, but calcium seen in CT or ultrasound excludes Coats in favor of Retinoblastoma. Other conditions such as Toxocara infection, retinopathy of prematurity, pars planitis, familial exudative vitreoretinopathy, retinal metastatic lesions, Norrie disease, Eales disease, cavernous retinal hemangioma and leukemia, should be considered.

Feature Coats Disease Retinoblastoma
Presentation Older patient, Unilateral, Male Younger presentation, Maybe bilateral, Unisex
Leukocoria Grey to pink White
Telangiectasia Classic, Vessels can be traced With tumor infiltration, Vessels dip into the mass
Vitreous seeding Absent Maybe present
Calcification Not a feature Seen on USG, CT Scan
Intraocular mass Not a feature Seen in endophytic cases
FFA Leaks with telangiectatic vessels Double circulation


The treatment of choice ranges from cryopexy or laser treatment for milder cases to a combination of both for more severe cases of Coats disease, sometimes with the addition of scleral transplant or Vitreo-retinal surgery in general. In addition Anti-VEGF therapy has been promising but the safety profile for children is as yet unclear. Finally enucleation of the eye is deemed in painful glaucomatous eyes.


The prognosis depends on the extent of the disease with milder, older presenting cases, having a better prognosis, of even spontaneous regression, whereas children under the age of three have a poorer prognosis.

Additional Resources


1) Nikolaos Tr Stagkos, Kliniki Ophthalmologia, Thessaloniki- Greece, Aristotelian University Press,2002.
2) American Academy of Ophthalmology. Pediatric Ophthalmology and Strabismus BCSC, Leo, 2011-2012.
3) Jack J. Kanski- Brad Bowling, Clinical Ophthalmology- A systematic approach, Seventh Edition, Elsevier, 2011.
4) Hoyt and Taylor, Pediatric Ophthalmology and Strabismus, fourth edition, Eslevier, 2012.