Collie eye anomaly is an inherited condition in which, during the embryonic stage, your dog's eyes develop abnormally. The consequences of this abnormal development range from minor vision impairment to total blindness.

Several breeds and mixes may develop this condition. These include Collies, Shetland Sheepdogs, and Border Collies.

CEA occurs in varying degrees of severity. The mildest form of CEA is called choroidal hypoplasia, and choroidal hypoplasia CEA makes up the majority of cases of CEA. The choroid is a layer of blood vessels behind the retina that helps to deliver oxygen and nutrients to the retina, and choroidal hypoplasia refers to the underdevelopment of this layer. Choroidal hypoplasia will not impact your dog’s vision. However, for about 25% of dogs with choroidal hypoplasia CEA, related eye problems occur that may cause either impaired vision or vision loss. The most common related eye condition accompanying choroidal hypoplasia are colobomas of the optic nerve. A coloboma of the optic nerve can be understood as a hole in the eye’s optic nerve. A coloboma of the optic nerve, especially if it is large, can allow fluid to build up behind the retina which, in some cases, can lead to retinal detachment. In addition, retinal bleeding can sometimes also occur as a complication. In these cases, which occur in approximately 7% of dogs with choroidal hypoplasia CEA and generally occur by the time your dog is 2 years old, impaired vision or even vision loss can result