Coats’ Disease and Leber’s Miliary Aneurysm

Signs and Symptoms
The patient with Coats’ disease and Leber’s miliary aneurysm typically is male and younger, with most diagnoses occurring between the ages of 18 months and 18 years. The patient frequently is asymptomatic; however, vision in advanced cases may be greatly reduced. Patients with Leber’s miliary aneurysm are more likely to be asymptomatic than patient’s with Coats’ disease. Both Coats’ disease and Leber’s miliary aneurysm are unilateral conditions.

Leber’s miliary aneurysm presents as a localized cluster of dilated capillaries, aneurysms, and telangiectasia, typically in the superior temporal quadrants of the retina. However, hemorrhage and exudation are minimal to absent in Leber’s miliary aneurysm. It is this absence of leakage which separates Leber’s miliary aneurysm from Coats’ disease. In fact, Leber’s miliary aneurysm is most likely a variant of Coats’ disease, albeit a much more mild form.

Coats’ disease has a much more dramatic appearance, ranging from mild exudation to massive aneurysmal exudation and exudative retinal detachment. There will be retinal edema, intra- and sub-retinal mounds of exudate, retinal detachment, vitreous hemorrhage, and possible neovascularization.

Pathophysiology
The formation of retinal telangiectasia and breakdown of the inner blood-retinal barrier are the fundamental causes of all changes found in Coats’ disease. Due to capillary closure at the telangiectasia, retinal neovascularization with subsequent vitreous hemorrhage and tractional retinal detachment can also occur. There appears to be a macrophage-related deposition of lipid into the deep retina and sub-retinal areas, giving Coats’ disease its characteristic exudative appearance. Untreated, there will be gradual progression to total exudative retinal detachment.

Management
The prognosis for Coats’ disease is guarded. Treatment is laser photocoagulation or cryoretinopexy for thermal necrosis of the abnormal vessels. In cases of retinal detachment, scleral buckle procedures are employed. In extreme cases where blindness ensues, pain relief is indicated. Obtain retinal consultation for Leber’s miliary aneurysm. You may also need to have the unleaking vessels thermally obliterated before significant leakage and exudation occurs.

Clinical Pearls

One quarter of cases of Coats’ disease are discovered in asymptomatic patients during routine examination.

Coats’ disease is a prime reason why clinicians should routinely dilate asymptomatic young patients.

Coats’ disease and Leber’s miliary aneurysm are likely different ends of the spectrum of the same disease. Coats’ disease is exudative, but Leber’s miliary aneurysm is not.

When massive exudation occurs due to another disease, it is termed Coats’ response.