One of the more miraculous parts of the mammalian body is the retina, a structure that fits snugly and smoothly against the inside back wall of the eyeball. The retina is responsible for sending visual images to the brain via the optic nerve. Or, in other words, it acts as the "film" in the camera that is vision. When the retina becomes separated from the support tissue underneath (the choroid, which supplies the retina with blood and oxygen) it can no longer function and is termed "detached." If not treated promptly and properly, the affected animal will become blind, sometimes within a matter of days.
Detached retinas have many causes. An injury to the eye or face can create a detachment, as can tumors and diseases like diabetes, high blood pressure, lupus, kidney disease and sickle cell anemia. In some cases, a detached retina can occur as a complication during cataract surgery or other types of eye surgery. In dogs, the cause most often is a disease-related accumulation of fluid underneath the retina that separates it from the choroid. Detached retinas can occur at any age and can affect one or both eyes, depending upon the underlying cause.
Symptoms of a detached retina are not painful, and they can appear either suddenly or gradually, depending upon whether the cause is injury- or disease-related. Since your dog obviously can't tell you how well it's seeing, pet owners should be alert. If the detached retina is in only one eye, the dog's behavior may be normal, yet the pupil of the affected eye will dilate and remain dilated as the dog's vision decreases. Retinal detachments caused by disease or infection usually occur rapidly, and the dog may lose its vision within one to three days. In some cases, there may be a visible hemorrhage or discoloration in the front part of the eye.
In rare cases, detached retinas also are associated with inherited birth defects of the eye, including retinal dysplasia and collie eye anomaly. Often they are seen in dogs with predominantly white coats. They also may appear in puppies whose mothers had poor nutrition or else were exposed to radiation and/or serious infections during pregnancy.
Some types of retinal detachments are easily diagnosed, while others can be difficult to see. An assessment by a veterinary ophthalmologist may be required in some cases. Once diagnosed, detached retinas must be treated right away, for there to be any chance of the dog retaining its vision. Usually treatment includes medications to address any underlying disease conditions. Eyes that are severely injured or affected by tumors may have to be surgically removed. Detachments caused by congenital defects or degenerative diseases of the retina generally are not treatable. In some cases, cryosurgery and/or laser therapy may be used to treat partial detachments, especially those that occur as a complication from cataract surgery or other surgical procedures on the eye.