Blindness in Cats
Dr. Noelle McNabb
Blindness is the loss of vision in both eyes. Vision loss may arise from disorders of the structures that receive and process the image within the eye, or from disorders of the visual pathways that transmit and further process the image within the brain. Occasional clumsiness
Acute (sudden) blindness occurs when vision is lost in both eyes simultaneously. The actual onset of blindness may be difficult to pinpoint because cats' senses of hearing and smell can often compensate for a decrease in vision. When one eye is blind, most cats act and behave normally. The owner may not realize vision has been lost in one eye, until such time as it is decreased in the other eye. If an acute loss of sight occurs in the other eye from a disease or injury, then the cat may seem to go acutely blind.
At times the realization that the pet is blind only occurs when a change in the environment confuses the pet. Animals that slowly lose their vision memorize their surroundings, and if those surroundings are altered, then the behavioral changes exhibited by the cat may make the owner conclude that the cat has gone blind suddenly. In actuality, the blind cat starts bumping into things only because the environment has changed.
Blindness in some pets may not be observed until vision is lost in eyes that had minimal function previously. Common causes of either acute or chronic vision loss include severe corneal disease, severe anterior and/or posterior uveitis, cataracts (white opacity of the lens), retinal inflammation and infection, retinal detachment, glaucoma (sustained elevated pressure within the eye), disease of the optic nerve (nerve that connects the eye to the brain) and visual pathways, and diseases of the occipital cortex (visual center of the brain).
What to Watch For
Bumping into objects
Inability to find food and water dishes
Inattentive behavior, excessive sleeping
Easily startled, fearful behavior
Loss of normal play or hunting behaviors
Diagnostic tests are essential in determining the exact cause of the blindness. Tests may include:
Complete physical examination
Complete ophthalmic examination, including direct and indirect ophthalmoscopy, pupillary light reflex testing, slit-lamp biomicroscopy, tonometry, Schirmer tear testing, navigation of the pet through an obstacle course, visual tracking and visual placing tests, and fluorescein staining of the cornea.
Complete neurologic examination
Other Diagnostic Tests
Complete blood count (CBC) and serum tests via blood samples
Blood pressure testing
Visually evoked response test
Specific serologic tests
Cerebral spinal fluid tap
Specialized imaging tests of the eye and skull, such as ultrasound examination, CAT scans or MRI
Successful treatment depends on obtaining an accurate diagnosis.
Pets with recent onset of blindness should be evaluated by your veterinarian as soon as possible. Minimize stress and injury by confining your pet to a safe area until the cause of the problem is determined. Place barriers across staircases, over hot tubs and around pools. Restrict activity on balconies if your pet could fall through the guardrails.
Establish a known location for the food and water bowls and guide your pet to them if necessary; do not change his environment.
Do not allow your pet to scratch or rub his eyes if he appears painful, as this may cause further damage to the eye. Use an Elizabethan collar if necessary.