Coats Disease

Coats disease is a rare eye condition in which small blood vessels of the retina become abnormally altered and leaky. Fluid and fatty deposits (lipids) escape from the vessels and collect in and under the retina. At an advanced stage the retina can detach. The condition almost always affects only one eye, occurs predominantly in boys and is not inherited.

Causes

The exact cause of Coats disease is unknown. It is not an inherited condition and there is no connection with other underlying illnesses. The abnormal vascular changes (telangiectasias) are congenital and develop in early childhood.

Signs and symptoms

Because Coats disease usually affects only one eye, it often does not stand out immediately in everyday life. Typical signs are:

• Leukocoria (white pupillary reflex): instead of the familiar red reflex in flash photographs, the pupil appears whitish or yellowish. This is frequently the first sign for parents.
• Squinting (strabismus): an eye deviating inward or outward can be a sign of deteriorating vision
• Deterioration of visual acuity: blurred vision or difficulty recognising objects
• Eye pain: occurs mainly in advanced disease with raised intraocular pressure

Diagnosis

The diagnosis is made through a thorough examination of the back of the eye. The ophthalmologist identifies the typical dilated, tortuous retinal vessels and accumulations of fluid. Additional investigations can include:

• Fluorescein angiography: to show the blood flow and the leaking vessels
• Ultrasound: to assess the interior of the eye, particularly in advanced disease
• Optical coherence tomography (OCT): detailed imaging of the retinal layers

An important task of the diagnostic work-up is to distinguish the condition from retinoblastoma, a malignant eye tumour in children, which can likewise present with leukocoria.

Stages

Coats disease is divided into five stages:

1. Stage 1: abnormal blood vessels without leakage of fluid
2. Stage 2: vessels begin to leak: with slight leakage vision remains normal, with more pronounced leakage it can deteriorate
3. Stage 3: partial retinal detachment due to accumulated fluid
4. Stage 4: complete retinal detachment, often combined with raised intraocular pressure (glaucoma)
5. Stage 5: blindness of the affected eye, possibly with pain

Treatment

Treatment depends on the stage of the disease:

Observation

In very early stages without leakage of fluid, regular monitoring can be sufficient. The ophthalmologist examines the eye at set intervals in order to detect progression in good time.

Laser therapy and cryotherapy

Leaking vessels are sealed with laser or cold probes (cryotherapy) in order to stop the leakage of fluid. Several sessions are often needed.

Anti-VEGF injections

Medicines that block the growth factor VEGF are injected directly into the eye. They can reduce the leakage of fluid and are frequently used alongside laser or cryotherapy.

Vitrectomy

In advanced disease with extensive retinal detachment, surgery on the vitreous body can be necessary.

Prognosis

The visual prognosis depends substantially on the stage at which the disease is discovered and how quickly it progresses. Younger children often have a more severe course. With early diagnosis and consistent treatment, vision can be preserved or stabilised in many cases. Most patients nevertheless retain reduced visual acuity in the affected eye.

Follow-up

After treatment, regular check-ups are essential in order to detect any recurrence of the vascular changes early. In children with reduced vision in one eye, correction with glasses or occlusion treatment (patching therapy) can be useful in addition, in order to encourage the best possible vision.