Coats disease

From EyeWiki
Original article contributed by: Kleonikos A. Tsakiris, MD, MSc, FEBO
All contributors: K. David Epley, M.D., Kleonikos A. Tsakiris, MD, MSc, FEBO, Leo A. Kim, MD and Vinay A. Shah M.D.
Assigned editor: Leo A. Kim, MD
Review: Assigned status Update Pending by Vinay A. Shah M.D. on August 24, 2015.
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Coats disease is a telangiectasia, neovascularization disease, of unknown aetiology, that freuquently affects unilateral eyes of young children, mainly boys

Disease Entity[edit | edit source]

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.

Disease[edit | edit source]

The disease is primarily due to aneurismatic 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

Etiology[edit | edit source]

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.

Signs and Symptoms
[edit | edit source]

Presenting symptom is frequently leukocoria but the diagnosis is determined fundoscopically. In mild cases one or two focuses 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[edit | edit source]

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.

Staging [edit | edit source]

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[edit | edit source]

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. Others such as Toxocara infection, retinopathy of prematurity, pars planitis, familial exudative chororetinopathy, PVF, metastatic retinitis, Norris disease, Eales disease, cavernous retinal hemangioma and leukemia, should be considered.

Treatment[edit | edit source]

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

Prognosis[edit | edit source]

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 more severe one.

Additional Resources[edit | edit source]

AAPOS Resource

Information for parents

Office of rare diseases on Coats disease

References[edit | edit source]

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.