Coats disease refers to an eye disorder where blood vessels develop abnormally in the retina. The retina is responsible for sending light signals to the brain, which are then converted into images. The symptoms begin manifesting in childhood, and often only one eye is affected. Without treatment, the disease can lead to serious eye conditions such as glaucoma, cataracts, and retinal detachment. Retinal detachment occurs when the damaged capillaries in the retina leak fluid leading to the retina's swelling. The disease is said to affect more males than females.
Also Known As
- Coats syndrome
Causes & Risk Factors
Coats disease has no known direct cause. However, researchers believe the NDP gene mutations could be responsible. Despite the theories behind its cause, it’s generally acceptable that the disease is not inherited.
Signs & Symptoms
The signs and symptoms of Coats disease often begin in childhood. Mild symptoms may present in these beginning stages but progress to more severe ones. However, some patients may experience severe symptoms immediately. The symptoms are usually experienced in one eye, although some people may be affected in both eyes.
Early signs and symptoms include:
- Reduced vision
- Loss of depth perception
- Strabismus (misalignment of the eyes)
- Abnormal blood vessels in the peripheral retina
- Leukocoria (abnormal light reflection from the eye which appears white)
- The iris having a reddish discoloration caused by the growth of new blood vessels
The symptoms that present later include:
- Retinal detachment
- Atrophy of the eyeball
- The affected eye shrinking
- Uveitis or inflammation of the eye
- Glaucoma which may be accompanied by pain
The signs and symptoms are classified into five stages. These stages help the doctor determine the best treatment option and also aids in long-term follow-up.
- Stage 1 - The retinal telangiectasia phase, where the capillaries dilate. Though the blood vessels are abnormal, they do not leak
- Stage 2 - The retinal telangiectasia phase, along with the leaking of blood vessels into the retina. Extrafoveal leakage (outside of the fovea) also characterizes this stage. The fovea is located inside the retina and provides sharp, central vision. Leakage from the vessels can also occur within the fovea. If large fluid quantities leak and affect the retina’s centre, vision may be lost
- Stage 3 - This stage is marked by exudative retinal detachment and further divided into a total and partial retinal detachment
- Stage 4 - Glaucoma occurs in addition to a total retinal detachment
- Stage 5 - The end-stage of the condition where a total retinal detachment usually occurs together with phthisis bulbi (eyeball atrophy) and cataract. The eye is described as blind and may present with pain
Diagnosis of Coats disease is made through the following:
- A thorough ophthalmic assessment
- A detailed medical history of the patient
- A thorough clinical evaluation where the retinal vessels are visualized directly
- Special imaging tests that include ultrasound, diagnostic echography, optical coherence tomography, and fluorescein angiography
Treatment aims to manage the specific signs in each patient. Early treatment will help check the disease’s progression and register better results. The following treatment options can be used alone or in combination:
- Eyeglasses and patching therapy. In the case of amblyopia, these can be used
- Medications - Anti-VEGF drugs are injected into the eye to prevent the growth of new blood vessels. Anti-inflammatory steroids are also injected into the eye to reduce the swelling and leakage from the blood vessels
- Cryotherapy - This is a treatment method where the doctor uses cold therapy or freezing instruments. Cold therapy causes the blood vessels to be narrowed and creates a scar around these abnormal blood vessels, which stops the fluid from leaking
- Laser - Photocoagulation heats and destroys the abnormal blood vessels. This method can be used alone or in conjunction with cryotherapy
- Surgery - Surgery may be used in case of more serious complications like retinal detachment, cataract, and glaucoma. For instance, scleral buckling and vitrectomy can help treat a retinal detachment. If atrophy of the eye occurs in the end-stage disease phase, enucleation is performed to remove the eyeball
Prognosis & Long-Term Outlook
The prognosis depends on many factors such as when the disease was diagnosed, disease stage, rate of progression, and the effectiveness of treatment. Coats disease in younger children (less than three years old) is more aggressive and characterized by a retinal detachment. This may lead to poor vision in the affected eye. Some of the children and young adults who present with the disease at an older age respond to treatment where vision is preserved. Often the disease is milder in such. However, some people (about 25%) do not respond to treatment, and Coats disease progresses even to the level of removing the eye.
Prevention & Follow Up
Close monitoring is necessary.