Enophthalmos in Cats

Enophthalmos, which is colloquially referred to as “sunken eyeball,” is a condition in which a cat’s eyeball sinks deeper than normal into the orbit, or eye socket. It can occur in one or both eyes. This can be a congenital condition from birth, it can occur gradually as the result of a disease, or it can happen suddenly as a result of trauma. Depending upon the underlying cause, enophthalmos in cats can occur because of a change in the bone of the eye socket, a change in the volume of the eyeball, or the atrophy, or weakening, of the orbital muscles that hold the eyeball in place. The condition can appear as a drooping eyelid or as a small eyeball. If you suspect that your cat may suffer from enophthalmos, contact your veterinarian immediately as your cat’s vision is likely affected and it may be a sign of a serious or even life-threatening condition.

Symptoms of enophthalmos in cats are usually noticed as a change in the appearance of one or occasionally both eyes. If your cat is experiencing enophthalmos, you may notice one or more of the following:

• Eye that appears smaller or farther back in the socket than is usual
• A dramatically drooping eyelid
• Mucous coming from the sunken eye
• Elevated, and often reddened and inflamed, third eyelid
• Severe weight loss as a result of dehydration
• Constricted pupil
• Blindness in the affected eye
• Nasal discharge

There are numerous possible causes of enophthalmos, or sunken eyeball, in cats, which include the following:

• Severe dehydration, which causes a decrease in the fluid within the eye
• A mass growing in the eye socket or sinus cavity that is pushing the eye back in the socket
• A traumatic injury that damages the bone structure of the orbit
• Horner’s Syndrome, which is a disorder of the sympathetic nervous system that often results from a traumatic facial injury such as being hit by a car or a fight.
• Dangerously rapid and drastic weight loss that includes the loss of the fat that helps to hold the eyeball in place
• Although it is much more common in dogs, it is possible that a cat may have a congenital condition that results in one or both eyeballs being smaller than is normal

If your cat appears to have a sunken eye, your veterinarian will take several steps to diagnose the cause of enophthalmos, including:

• Listening to your observations regarding the symptoms you have observed and especially to when the symptoms began
• Reviewing your cat’s medical history
• Performing a thorough physical examination of your cat, paying special attention to the area around the affected eye
• Test the blood, urine, and/or feces for evidence of severe dehydration and to determine the overall health of your cat
• Order x-rays to determine if there is orbital damage to the skull or a mass growing near the eye socket

Treatment for enophthalmos generally consists of treatment for the underlying cause of the condition. The possible treatments are as follows:

• If dehydration is determined to be the cause, IV fluids to rehydrate your cat
• If a growth in the anterior, or front, area of the eye socket is found to be present and pushing the eyeball back in the socket, the veterinarian, often in consultation with a veterinary surgeon, may determine that it is in the best interest of your pet’s health to surgically remove the growth, therefore releasing the pressure that is pushing the eyeball backward.
• If the growth is found to be cancerous, chemotherapy may be ordered in an effort to rid your cat’s body of possibly fatal cancer.
• Surgery may also be required to repair the orbital socket or sinus cavities in the case of a traumatic facial injury that likely occurred as the result of being hit by a car or injured in a fight with a larger or wild animal.
• In the case of Horner’s Syndrome or in idiopathic cases, meaning that the cause of the enophthalmos is unknown, your vet may choose to keep the eye clean and possibly administer medicated eye drops while waiting to see if the condition will resolve on its own without any further treatment.

Your cat’s recovery is dependent upon the underlying cause of the enophthalmos, your cat’s overall health, and how quickly your cat received treatment after you noticed the sunken appearance of the eye or eyes. If the cause of your cat’s enophthalmos is dehydration, rehydration may return the eye to its proper size if treatment is received soon enough. If the cause is a growth, your cat’s recovery is dependent upon whether or not the growth could be removed and whether or not it was cancerous. If the grown was cancerous, recovery is dependent upon if the cancer had spread to other areas of the body, especially into the brain. In the case of a traumatic injury, your cat’s recovery is dependent upon how severe the cat’s injuries are and if your cat is able to heal from those injuries. It is difficult to state the predicted prognosis for cats with enophthalmos because the condition is almost always a symptom of a larger underlying health issue.