What is Coats disease?

Coats disease is a rare eye disorder involving abnormal development of blood vessels in the retina. Located in the back of the eye, the retina sends light images to the brain and is essential to eyesight.

In people with Coats disease, retinal capillaries break open and leak fluid into the back of the eye. As fluid builds up, the retina begins to swell. This can cause the partial or complete detachment of the retina, leading to decreased vision or blindness in the affected eye.

Most of the time, the disease affects only one eye. It’s usually diagnosed in childhood. The exact cause isn’t known, but early intervention may help save your vision.

Signs and symptoms usually begin in childhood. They may be mild at first, but some people have severe symptoms right away. Signs and symptoms include:

  • yellow-eye effect (similar to red eye) that can be seen in flash photography
  • strabismus, or crossed eyes
  • leukocoria, a white mass behind the lens of the eye
  • loss of depth perception
  • deterioration of vision

Later symptoms may include:

  • reddish discoloration of the iris
  • uveitis, or eye inflammation
  • retinal detachment
  • glaucoma
  • cataracts
  • eyeball atrophy

Symptoms usually occur in only one eye, although it can affect both.

Coats disease is a progressive condition that’s divided into five stages.

Stage 1

In early-stage Coats disease, the doctor can see that you have abnormal blood vessels, but they haven’t started to leak yet.

Stage 2

The blood vessels have begun to leak fluids into the retina. If the leak is small, you might still have normal vision. With a larger leak, you might already be experiencing severe vision loss. The risk of retinal detachment grows as fluids accumulate.

Stage 3

Your retina is either partially or totally detached.

Stage 4

You’ve developed increased pressure in the eye, called glaucoma.

Stage 5

In advanced Coats disease, you’ve completely lost vision in the affected eye. You may have also developed cataracts (clouding of the lens) or phthisis bulbi (atrophy of the eyeball).

Anyone can get Coats disease, but it’s quite rare. Fewer than 200,000 people in the United States have it. It affects males more than females by a ratio of 3-to-1.

Average age at diagnosis is 8 to 16 years. Among children with Coats disease, about two-thirds have had symptoms by age 10. About one-third of people with Coats disease are 30 or older when symptoms start.

It doesn’t appear to be inherited or have any link to race or ethnicity. The direct cause of Coats disease hasn’t been determined.

If you (or your child) have symptoms of Coats disease, see your doctor right away. Early intervention might save your vision. Also, symptoms can mimic those of other conditions, such as retinoblastoma, which can be life-threatening.

Diagnosis is made after thorough ophthalmic examination, plus review of symptoms and health history. Diagnostic testing may include imaging tests such as:

  • retinal fluorescein angiography
  • echography
  • CT scan

Coats disease is progressive. With early treatment, it’s possible to restore some vision. Some treatment options are:

Laser surgery (photocoagulation)

This procedure uses a laser to shrink or destroy blood vessels. Your doctor may perform this surgery at an outpatient facility or in an office setting.


Imaging tests help guide a needle-like applicator (cryoprobe) that produces extreme cold. It’s used to create a scar around abnormal blood vessels, which helps stop further leakage. Here’s how to prepare and what to expect during recovery.

Intravitreal injections

Under a local anesthetic, your doctor can inject corticosteroids into your eye to help control inflammation. Anti-vascular endothelial growth factor (anti-VEGF) injections can reduce the growth of new blood vessels and ease swelling. Injections can be given in your doctor’s office.


This is a surgical procedure that removes the vitreous gel and provides improved access to the retina. Learn more about the procedure what to do while recovering.

Scleral buckling

This procedure reattaches the retina and is usually performed in a hospital operating room.

Whatever treatment you have, you’ll need careful monitoring.

In the final stage of Coats disease, atrophy of the eyeball may result in surgical removal of the affected eye. This procedure is called enucleation.

There’s no cure for Coats disease, but early treatment can improve your chances of retaining your eyesight.

Most people respond well to treatment. But about 25 percent of people experience continued progression that leads to removal of the eye.

The outlook is different for everybody, depending on stage at diagnosis, rate of progression, and response to treatment.

Your doctor can assess your condition and give you an idea of what you can expect.