|Coats Disease and
Lebers Miliary Aneurysm
Signs and Symptoms
The patient with Coats disease and Lebers 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 Lebers miliary aneurysm are more likely to be asymptomatic
than patients with Coats disease. Both Coats disease and Lebers
miliary aneurysm are unilateral conditions.
Lebers 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 Lebers
miliary aneurysm. It is this absence of leakage which separates Lebers miliary
aneurysm from Coats disease. In fact, Lebers 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.
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.
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 Lebers miliary
aneurysm. You may also need to have the unleaking vessels thermally obliterated before
significant leakage and exudation occurs.
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 Lebers miliary aneurysm are
likely different ends of the spectrum of the same disease. Coats disease is
exudative, but Lebers miliary aneurysm is not.
When massive exudation occurs due to another disease, it
is termed Coats response.
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