What Is Coats Disease?

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Coats disease is a rare disorder in which abnormal vessels develop within the light-sensitive retina at the back of the eye. This condition is usually detected in the first decade of life. While it's not clear exactly why, it can cause fluid to leak from the blood vessel walls into and beneath the retina and damage it.

In nearly all cases (90%), Coats disease affects only one eye. It also primarily affects males (70% to 90% of cases). While most of those impacted are children, it can affect people up until around age 80.

This article will examine the potential causes of Coats disease, how it is diagnosed, the treatment options available, and more.

Checking girl's eyes

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Coats Disease Symptoms

Detecting Coats disease may initially come down to symptoms, including:

  • Vision loss
  • Eye misalignment (strabismus), in which the eyes move in different directions
  • White reflex rather than a red or orange reflex, meaning when a light is shined into the eye in a darkened room or in flash photography, the pupil appears white (leukocoria) instead of reddish
  • Pain caused by increased eye pressure

After an eye exam, an ophthalmologist (eye doctor) may also mention clinical signs such as:

  • Abnormal peripheral blood vessels
  • Retinal swelling
  • Retinal detachment (severe cases), in which the light-sensitive retina separates from the back of the eye


Unfortunately, the cause of Coats disease is unknown. While Coats disease is not considered an inherited condition, there is some evidence that a mutation of a gene known as the Norrie disease protein (NDP) may be involved. This protein plays a key role in retinal blood vessel development. While this was shown to be a real possibility by one study, further research has not been able to substantiate this.


To diagnose Coats disease, an ophthalmologist needs to evaluate the eyes. After giving a detailed history, here are some tests you can expect to undergo, such as:

  • Retinal fluorescein angiography: With a special camera and dye, the ophthalmologist can get a look at the retinal blood vessels.
  • Diagnostic echography: This test uses high-frequency sound waves to produce images of the eye to aid in diagnosis.
  • Optical coherence tomography (OCT) of the eye: This is an imaging technique that uses low-coherence light to capture high-resolution cross-sectional images of the retina.


Coats disease can be progressive, and patients may be treated to slow this progression. The earlier this can be stopped, the better.

Potential treatments include:

  • Cryotherapy (freezing) can be used to create scarring around abnormal blood vessels and keep them from leaking. Or, laser energy (photocoagulation) can be applied to destroy these blood vessels with the aid of heat.
  • In combination with cryotherapy or photocoagulation, steroids can help control inflammation and subsequent blood vessel leakage.
  • Anti-vascular endothelial growth factor (anti-VEGF) injection treatment can reduce the formation of leaky abnormal blood vessels and help avoid possible retinal detachment.
  • A vitrectomy (removing the jelly of the eye and replacement with saline solution) can be performed to avoid more severe retinal detachments.
  • Treatment to prevent amblyopia, in which the brain doesn't recognize vision from the weaker eye, may include wearing a patch over the stronger eye to prevent vision loss in the weaker one.


Understanding the prognosis for someone with Coats disease means weighing certain factors. In general, the younger the person, the more aggressive the disease.

When Coats disease occurs in someone under age 3, it suggests that the disease is likely to be more aggressive. Likewise, in cases in which Coats disease is identified years later, it's generally not as severe.

There are five stages of Coats disease. The earlier it is identified, the more opportunity there is to treat it effectively. The five stages include:

  • Stage 1: The blood vessels in the eye are already abnormal but have not yet begun to leak.
  • Stage 2: Fluid has begun leaking onto the retina from the blood vessels. The amount of damage is tied to how much fluid has leaked and where in the retina this is. If the center of the retina is still spared, vision may remain good. But if the retina has been compromised, there may be severe visual loss.
  • Stage 3: A retinal detachment has occurred.
  • Stage 4: Pressure rises in the eye, and glaucoma (damage to the optic nerve due to high intraocular pressure) is diagnosed.
  • Stage 5: This final stage may involve pain due to increased eye pressure and possible eventual blindness

Coping With Coats Disease

Coats disease is often diagnosed in children. This can bring up many normal emotions. Learn as much as you can about the condition to empower yourself. The more you know, the more proactive you can be.

Remember, this is not a life-threatening condition, and there are several treatments that can help. Even with severe vision loss, only one eye is affected in most cases.

With a condition such as Coats disease, it can be helpful to reach out to other families who are already dealing with this and who understand what you are going through.


Coats disease generally is diagnosed in one eye in male children under the age of 10. This condition involves abnormal blood vessels that leak onto the retina causing vision loss. Fortunately, there are treatments to help keep this from happening.

The prognosis here tends to depend on the age of the person diagnosed and the stage at which it is identified. If you have this condition or have a child who does, the more you know about Coats disease the more empowered you can be.

A Word From Verywell

Fortunately, a lot is known about Coats disease. While it can affect the retina and cause vision loss, if caught early, there are several treatments that can work to keep this in check and help to preserve vision. It can also be useful to reach out to others who have been affected by this condition.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Pediatric Retinal Research Foundation. Coats' disease.

  2. National Organization for Rare Disorders. Coats disease.

  3. American Association for Pediatric Ophthalmology and Strabismus. Coats' disease.

By Maxine Lipner
Maxine Lipner is a long-time health and medical writer with over 30 years of experience covering ophthalmology, oncology, and general health and wellness.