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Genetic and Rare Diseases Information Center (GARD)

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Coats disease


Other Names for this Disease
  • Retinal telangiectasis
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Your Question

My 2 year old son was recently diagnosed with Coats disease stage 3a. I would love to know more about this, the various stages and what happens in them, and the possible treatments and long term prognosis.

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is Coats disease?

Coats disease is an eye disorder characterized by abnormal development of the blood vessels of the retina (retinal telangiectasia). Signs and symptoms differ depending on the extent and size of blood vessels involved; some individuals are asymptomatic while others are severly affected. Symptoms typically begin at an early age (most commonly between ages 6 to 8) and may include vision loss; crossed eyes (strabismus); a white mass in the pupil behind the lens of the eye (leukokoria); and/or retinal detachment. In most cases, only one eye is affected (unilateral) but in rare cases both eyes are affected (bilateral). The cause is not exactly known but some cases may be due to somatic mutations in the NDP gene. Treatment depends on the symptoms present and may include cryotherapy, laser therapy, photocoagulation and/or surgery.[1][2]
Last updated: 12/5/2011

What are the signs and symptoms of Coats disease?

The signs and symptoms in affected individuals depend on the extent and size of the blood vessels involved.[1] Some individuals may be asymptomatic while others are very severely affected. Signs and symptoms typically begin at an early age (most commonly between ages 6 and 8).[2] The disease is almost always progressive, although alternating periods of acute worsening with periods of no apparent progression are common.[2] Affected individuals may first experience loss of vision; crossed eyes (strabismus); and/or the development of a white mass in the pupil behind the lens of the eye so that the pupil appears white (leukokoria or "cat's eye" reflex).[1] As the disease progresses, individuals may develop glaucoma; cataracts; reddish discoloration in the iris (rubeosis iridis or neovascular glaucoma); shrinking of the affected eyeball (phthisis bulbi); and/or swelling and irritation of the middle layer of the eye (uveitis). The majority of affected individuals eventually experience profound vision loss and retinal detatchment.[1][2]
Last updated: 12/5/2011

What are the stages of Coats disease?

The most recent proposed staging classification for Coats disease was developed on the basis of a large series of affected individuals. This classification may help in choosing the most appropriate course of treatment as well as predicting the long-term outcome for individuals with Coats disease:[2][3]

  • Stage 1 - retinal telangiectasia only (dilation of capillaries in the retina)
  • Stage 2 - telangiectasia and exudation (escape of fluids and material from blood vessels and deposition into surrounding tissues) 
    • A - extrafoveal exudation (exudation outside of the fovea, which is a small area in the retina responsible for the acute vision)
    • B - foveal exudation (exudation in the fovea)
  • Stage 3 - exudative retinal detachment
    • A - subtotal detachment 
      • 1 - extrafoveal
      • 2 - foveal
    • B - total retinal detachment
  • Stage 4 - total retinal detachment and glaucoma
  • Stage 5 - advanced end-stage disease (defined as a blind, non-painful eye with a total retinal detachment, often with cataract and phthisis bulbi)[3]
Last updated: 12/2/2011

What causes Coats disease?

The exact cause of Coats disease is not currently known. However, because it has been associated with different genetic syndromes, it has been thought to have a genetic component.[4] It has been suggested that some cases of Coats disease may be due to somatic mutations in the NDP gene, which may result in the deficiency of a protein called norrin in the developing retina.[5] A somatic mutation in this case is one that is acquired after an individual's conception (i.e. it was not inherited from a parent and cannot be passed on to an affected individual's children).
Last updated: 12/2/2011

How might Coats disease be treated?

The treatment of Coats disease depends on the signs and symptoms present in each individual and the stage at which the individual is diagnosed.[1] Treatment is usually directed towards closing the vessels that are leaking and salvaging as much vision as possible.[4] A procedure that uses extreme cold to destroy the blood vessels (cryotherapy), and/or a procedure that uses intense, focused light (laser therapy) to heat and destroy tissue may be used alone or in combination to treat the telangiectasia associated with the disease.[1] These procedures are commonly used during the early stages of the disease.[4] More advanced cases may require surgical treatment.[4]. Surgery to reattach the retina may be necessary for retinal detachment.[1] Drainage of fluid or surgically removing the substances that fill the eyeball between the lens and the retina (vitrectomy) may also be used to treat Coats disease when a retinal detachment is present. A procedure in which the vessels involved are heated and destroyed (diathermy) has also been used to treat the disease.[1]
Last updated: 12/5/2011

What is the prognosis for individuals with Coats disease?

Factors that effect the prognosis for an individual with Coats disease include the stage at which the individual is diagnosed, the rate of disease progression, and the effectiveness of treatment. An ophthalmologist with experience in the disease may be able to make a general prediction about the chances of retaining the eye and preserving vision. It has been reported that most individuals respond well to treatment, but approximately 25% become worse or require removal of the eye. The visual outcome in affected individuals varies considerably.[3]

When Coats disease is first diagnosed in older children and young adults, it tends to be less aggressive. In some older children and young adults, spontaneous regression has been reported. Observations have suggested if macular exudation and extensive retinal detachment (such as in stages 1 and 2A) are not present at diagnosis, a good visual outcome can be expected. However, if thick, foveal exudation is present (stage 2B disease and above), an individual usually has a worse prognosis. Most experts agree that visual prognosis is poor in individuals with total retinal detachment (stage 3B and above). Individuals with total retinal detachment usually have little or no useful vision in the affected eye despite treatment. Younger children typically have more aggressive disease and often have a total retinal detachment by the time they are diagnosed; these children usually have a poor visual outcome.[3]
Last updated: 12/5/2011

References