Coats Disease

Coats disease is usually a rare condition characterised by an abnormal, unilateral development of the retinal blood vessels. It can initially cause loss of vision, leukocoria or white pupil, and strabismus. In more severe cases it may lead to retinal detachment, neovascular glaucoma, cataracts or even a total loss of vision in the affected eye.

Although it can develop at any age, in most cases the process starts at a very young age. It often occurs in men and is diagnosed during the first two decades of the patient’s life.

The condition was named after the ophthalmologist George Coats, who discovered it in the early 20th century.

It is categorized as an idiopathic disorder, as its causes are unclear. No link to a genetic cause has been found, but numerous cases have been detected in patients with other diseases, such as retinitis pigmentosa.

This condition causes more visible symptoms when it occurs in very young patients. Some of the most common symptoms are: reduced visual acuity, low perception of light, strabismus or leukocoria (this occurs when white light is reflected in the patient’s pupil when it is directly illuminated).

In contrast, when Coats disease is diagnosed in adults, the disorder progresses slowly and patients are usually asymptomatic. Lesions appear in the periphery of the retina and lipid exudation is usually more localised.

As the pathology advances, symptoms such as telangiectasia (or spider veins), retinal exudation, cysts or aneurysms arise. There may even be more serious conditions such as retinal detachment, neovascular glaucoma, cataracts or even total loss of vision in the affected eye.

To diagnose Coats’ disease, the ophthalmologist performs an examination of the fundus of the eye. In addition, tests such as OCT (optical coherence tomography), medical ultrasound or fluorescein angiography may be performed.

The latter allows the specialist to identify spider veins, aneurysms and perivascular effusions at an early stage, as well as to determine the size of exudates.

During diagnosis, Coats’ disease must be distinguished from retinoblastoma (a cancer that originates in the retina and most often affects children) and from Leber’s miliary aneurysms (vascular alterations that may cause macular oedema and that more commonly affect adults). These pathologies share some symptoms such as telangiectasia or leukocoria.

Treatment may vary considerably depending on the patient’s age and the degree to which they are affected. The aim of most options is the resorption of the exudates by removing the spider veins.

Thus:

• when telangiectasia is mild and there is no exudation or imminent threat to vision, it is advisable to simply follow up with ophthalmological visits.
• in cases with spider veins and lipid exudation, but with no subretinal fluid (or with negligible amounts), a low-power, long-term laser treatment can be performed to remove the damaged vessel.
• if there is exudation with subretinal fluid, cryotherapy or cold therapy is recommended, with the same function as the laser.
• in more advanced cases, surgery may be performed to reposition the retina. The most common operations in these situations are scleral buckling, laser photocoagulation combined with pars plana vitrectomy and vitreous membrane removal.
• in some cases it may be recommendable to use intravitreal corticoid and anti-VEGF agents as adjuvant therapies, with the aim of preventing the body from producing new blood vessels when they are not required.

How is Coats disease identified?

The most common physical features include loss of vision and leukocoria. As it often affects only one of the two eyes, strabismus is also frequent.

If you experience any of these symptoms, you should see an ophthalmologist as soon as possible. Coats disease can only be correctly diagnosed (or ruled out) at a doctor’s surgery.

Can it be prevented?

Unfortunately, there is no known definitive way to prevent the disease. However, it is possible to anticipate and minimise the loss of vision in some cases with the appropriate treatment.

For this reason, it is important to have regular medical check-ups and to see an ophthalmologist as soon as symptoms appear.

Can it affect both eyes?

It is unlikely. In 95% of cases it occurs in only one of the two eyes.

What is its prognosis?

It may vary greatly depending on the case. It can range from a mild situation that resolves spontaneously without treatment, to a highly advanced case that leads to blindness in the affected eye. It depends on the age of the patient, the stage of the disease at the time of diagnosis, the conditions that have been triggered by it (if any), etc. In most cases, the symptoms can be relieved.

• Coats Disease, American Academy of Ophthalmology.
• Coats Disease, Medicine Net.