Proptosis (also called exophthalmos) is a medical condition in which one or both of the cat’s eyeballs is displaced and protrudes out of bony socket. This alarming condition is a medical emergency which requires immediate veterinary care.
It differs from buphthalmos, which is an enlarged globe usually caused by glaucoma.
The most common causes of proptosis include:
- Motor vehicle trauma
- Kick by a horse or person
- Fall from a height
- Eye tumour
What are the consequences of proptosis?
- When the eye protrudes, the eyelids become folded behind it which can cause the eye to dry out (dessicate) and ulcerate.
- Secondary hemorrhage (bleeding) and swelling can displace the globe further.
- Secondary infection can develop in the protruding eye.
All of these side effects can increase the risk of blindness due to globe perforation, damage to the optic nerve or necrosis.
The most obvious symptom is the protrusion of the eye from its socket with the eyelids behind it. Other symptoms of proptosis include:
- Dilated pupil(s)
- Dry and discoloured eye
- Swollen and bloody conjunctiva
- Bleeding inside the eye
- Pus and discharge from the affected eyeball
- Additional traumatic injuries may be present such as fractured bones (especially in the face and head)
The veterinarian will perform a physical examination which will include a thorough ophthalmological (eye) examination to evaluate the extent of the injury and assess the cat’s overall physical condition. A fluorescein stain may be placed in the eye to look for corneal ulcers.
Proptosis itself is easy to diagnose based on presenting symptoms, however the veterinarian will need to perform some tests to evaluate the eye and face. This will include skull and chest xrays to evaluate the facial structures, look for broken bones or tumours.
Treatment depends on the condition of the eye and surrounding tissues. Upon presentation, the veterinarian will apply topical antibiotic drops and lubricant to the exposed globe. It will be necessary to stabilise the cat and treat life-threatening injuries first.
Treatment for proptosis involves either replacing the globe or removal (enucleation).
Positive indicators for saving the eye:
- Mild proptosis
- A pupil which constricts when the veterinarian shines a light into it
- Positive menace response, in which the cat blinks when the veterinarian quickly moves a hand towards the eye
- Minimal eye damage
- The eye has only been out of place for a short time
The above points highlight the importance of immediate veterinary attention which can mean the difference between saving and losing the eye
- Severe proptosis
- Bleeding into the eye
- Dilated, unresponsive pupil
- Absent menace response
- Extraocular (muscles on the outside of the eye which are responsible for movement) muscle avulsion have torn away
- Optic nerve avulsion
If it is possible to save the eye, the veterinarian will place the cat under general anesthesia, clip and sterilise the eyelids, flush the eye with sterile saline to remove debris, the lids are unrolled and the globe is carefully pressed back into position with a moist surgical sponge. The eyelids are temporarily stitched shut (temporary tarsorrhaphy) to keep the eye in place for between 1-3 weeks.
If it is not possible to save the eye, the veterinarian will remove it along with the orbital tissues under general anesthesia. The eyelid is then sewn permanently shut.
Follow up care:
The cat will be sent home with a care sheet, topical antibiotics and painkillers and in some cases, anti-inflammatories. An Elizabethan collar will be necessary to prevent the cat damaging the area. Always follow your veterinarian’s instructions. Watch for signs of infection which include redness, pain and discharge.
The veterinarian will schedule a follow up appointment to monitor recovery. In some cases, enucleation may still be necessary later due to chronic uveitis or glaucoma.