Collie Eye Anomaly (CEA)
Collie Eye Anomaly (CEA) is an inherited disorder where tissues in the back of the eye do not differentiate and develop properly in the fetal puppy. The result is a group of defects which occur in varying degrees among different dogs, and even varying degrees between the right and left eyes of the same dog.
The primary defect is choroidal hypoplasia, where the choroid is under-developed. The choroid is a thin layer of blood vessels, sandwiched between the retina (most inner layer) and sclera (outer layer) of the back of the eye. The choroid supplies the retina with oxygen and nutrients, so when it is under-developed, the back tissues of the eye are receiving reduced levels of oxygen and nutrients.
Coloboma of the retina and/or optic disc may also be present in Collie Eye Anomaly. A coloboma is a hole or fissure in the tissue, typically caused by a failure of the embryonic tissue to close properly.
Staphyloma is also commonly associated with CEA. A staphyloma is a thinning in the sclera, which is the outer layer of the back of the eye.
Perhaps most significantly, retinal detachment, either complete or partial, is associated with CEA. Retinal detachment may or may not produce bleeding, but it is the possible result of the other CEA issues, and retinal detachment is the major contributor to the partial or complete blindness that can result from Collie Eye Anomaly.
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