Like other breeds of dogs, Collies are prone to several inherited eye defects, including the following:

• Collie Eye Anomaly / Choroidal Hypoplasia (CEA/CH)
• Persistent Pupillary Membranes (PPM)
• Progressive Retinal Atrophy (PRA)

Collie eye anomaly is a disorder marked by the incomplete development of the eye. The disorder is found in rough and smooth collies of all colors worldwide.

The cornea is the clear front part of the eye which acts like the windshield. It protects the insides of the eye and yet allows for a clear area for light to pass through. Corneal dystrophy is a disease of the cornea in which white opaque mineral (cholesterol or calcium) is deposited in the cornea. Corneal dystrophy might affect one or both eyes. The size, shape, and density of the dystrophic area are variable. Corneal dystrophy can occur in any age dog. Corneal mineralization can occur in three instances:

The cornea is normally the transparent “windshield” of the eye, serving to protect the internal structures of the eye while allowing light to enter for vision. The endothelium is a single layer of cells that lines the inside of the cornea. Though only a single cell layer thick, this layer is vital in maintaining a clear cornea for functional vision. The cornea normally maintains its clarity through a number of factors, including a very regular arrangement of supportive fibers and a relatively dehydrated state compared to other body tissues. If water is allowed to build up, the corneal fibers arrangement will be disrupted and the clarity of the cornea will be reduced.

The Disease and its Transmission

Ehrlichiosis (also called “tick fever”), a disease seen across the continental U.S. occurs with the most frequency in the southern states and desert states. Since systemic signs of this disease are often vague and mild in the early stages, ocular changes may be the first indication to test for Ehrlichiosis. Ocular manifestations include uveitis, retinal disease, and corneal opacities. Early detection, diagnosis and treatment greatly increase chances for saving vision and even the life of the pet.

A syndrome is a collection of symptoms that often has a limited number of causes and can thus help doctors diagnose the underlying problem.

• A constricted pupil (miosis)
• A drooping of the upper eyelid (ptosis)
• A sunken appearance of the eye (enophthalmos)
• An elevation of the third eyelid

These symptoms are not painful and do not interfere with vision, but are significant because collectively they indicate damage to the sympathetic nervous supply to the eye.