American Association for Pediatric
Ophthalmology and Strabismus

Coats Disease

What is Coats disease?

Coats disease is caused by a problem with the arteries and veins (blood vessels) inside the eye that provide blood and oxygen to the retina. In Coats disease, the blood vessels are dilated, abnormally twisted and leaky. This prevents the normal flow of blood, and allows fluid to leak out of the blood vessels causing a build up of fatty (lipid) material into the retina. If a large amount of fluid (exudate) builds up, it can cause a detachment of the retina and loss of vision. [See figures 1 and 2].

What are the stages of Coats disease and its effect on vision?

The disease progress is divided into five stages. In stage 1, abnormal blood vessels are seen in the retina but these vessels are not yet leaky. Stage 2 of the disease is characterized by leakage from the vessels into the retina. The effect on vision depends on the amount of fluid that has leaked into the retina and the size of the area involved. If only a small amount of fluid has leaked and the center of the retina is not involved, the vision may remain normal. If large amounts of fluid leak and/or the center of the retina is involved, vision loss can be severe. The accumulation of fluid leaking from the vessels can cause the retina to detach. The presence of such detachment takes the disease to stage 3. If this is further complicated with glaucoma (raised pressure of the eye), the disease classifies as stage 4. Stage 5 is the end stage of the disease when the eye becomes blind and may be painful due to the raised pressure inside the eye.

How is Coats disease treated?

Treatment is sometimes recommended to prevent progression of the disease. Better results are achieved when the disease is treated in the earlier stages. Laser or freezing treatments (cryotherapy) are often utilized to constrict the abnormal blood vessels and stop the leakage of fluid. Surgery may be needed in the advanced stages of the disease to treat retinal detachment.,
Continued monitoring is necessary to check for recurrence of the disease after treatment. Glasses and patching therapy for amblyopia are sometimes necessary. The majority of patients with Coats disease ends with vision less than normal in the affected eye.