Coat’s Disease is also called congenital telangiectasia. It is related to type 1 macular telangiectasia, since it involves localized dilations, or aneurysms, of blood vessels throughout the retina. Leber’s Miliary Aneurysm is an interchangeable term for the mildest form of Coat’s Disease; the mild form often involves no vision loss and no exudates. In more severe forms, the aneurysms bleed into the back of the eye, and cholesterol from the leaking blood is left behind on the retinal cells.
Coat’s Disease is similar to type 1 macular telangiectasia because it usually affects only one eye and usually occurs in males. The difference is that Coat’s Disease is present at birth and is very often diagnosed in early childhood. Some researchers have suggested that Coat’s Disease may be caused by a genetic mutation, but this is not known for certain.
Coat’s Disease, in its more severe form, causes a gradual deterioration of vision and often results in retinal detachment. The progression of Coat’s Disease can sometimes be stopped by laser surgery or cryotherapy. These treatments can not be used if the capillaries affected are near the optic nerve, or it Coat’s Disease has progressed too far. Few children with Coat’s Disease are diagnosed at a stage at which surgery or cryotherapy can stop the progression of the disease because they are often too young to explain the symptoms of the disease or describe their vision loss. In addition to retinal detachment, glaucoma, atrophy, or cataracts may occur as Coat’s Disease progresses. Unfortunately, removal of the affected eye may be an eventual outcome.
A diagnosis of Coat’s Disease can be frightening and devastating—for both the child who has received the diagnosis and his parent. It is important for a parent to try to maintain an optimistic attitude and encourage his or her child to adapt to vision loss by relying on— and protecting—the non-Coat’s eye.