What are the third eyelid and third eyelid gland?
Dogs have three eyelids, the third eyelid being an extra eyelid that sweeps back and forth across the surface of the eye providing protection and spreading the tear film. The third eyelid is also called the nictitating membrane. The tear film is produced by two glands, namely the third eyelid gland (nictitans gland) and the lacrimal gland. The third eyelid gland is attached to the base of the third eyelid where it is not normally visible.
What is the function of the third eyelid gland?
The third eyelid gland produces approximately 60% of the tear film and therefore has an essential role in keeping the surface of the eye wet. If the surface of the eye is dry, the eye becomes uncomfortable and susceptible to developing conjunctivitis, abnormal discharges and corneal ulcers.
What does ‘third eyelid gland prolapse’ mean?
The gland is held in its normal position at the base of the third eyelid by a small ligament which attaches it directly onto the bone of the eye socket. If the ligament breaks the gland becomes mobile, prolapsing from its normal position and becoming visible above the edge of the third eyelid.
Why is it called ‘cherry eye’?
The prolapsed third eyelid gland is visible as a pink mass or ‘lump’ near the inner corner of the eye and resembles a cherry, hence the common term ’cherry eye’.
How does the prolapsed gland affect the eye?
The gland does not produce tears effectively when it is in the wrong position, causing the surface of the eye to become dry. Although the condition is not usually painful it may cause minor irritation, conjunctivitis and increased discharge from the affected eye.
Is my dog or cat at risk?
Third eyelid gland prolapse is much more common in dogs than in cats. It usually affects young dogs between the ages of 6 to 12 months, although there is some variation in the age of onset. Predisposed breeds include the Bulldog, Shih Tzu, Lhasa Apso, Cocker Spaniel, Great Dane and Mastiff.
Can it affect the other eye?
Yes. Third eyelid gland prolapse usually affects both eyes but not necessarily at the same time. The second eye often becomes affected after an interval of a few weeks to months.
What are the treatment options?
The recommended treatment is surgery to replace the gland to its normal position at the base of the third eyelid where it cannot be seen and can function normally. There are several different surgical techniques that can be performed. Removal of the gland is not a suitable option as it predisposes the eye to low tear production (‘dry eye’) later in life. Some breeds such as the Bulldog are predisposed to both ‘cherry eye’ and ‘dry eye’ conditions and it is therefore particularly important in such breeds that the prolapsed gland is replaced and not removed. If the gland is left untreated it will not produce tears normally and may become enlarged and red, causing discomfort.
What is involved with the surgery?
Your pet will stay in the hospital for the day and undergo a general anaesthetic for the ‘pocket’ technique to be performed. This technique involves the creation of a small space or ‘pocket’ on the back of the third eyelid into which the gland can be placed and permanently secured by suturing the overlying tissue.
What after-care is required?
The after-care is routine in most cases. Your pet will need post-operative medication which may include tablets (antibiotics and painkillers) for several days and eye drops or eye ointment for one to two weeks. Exercise will need to be limited for a few days. Absorbable stitch material is used, hence stitch removal is not necessary. A Buster collar is usually not necessary after this type of surgery.
Are there any complications following surgery?
The ‘pocket’ technique is successful in 90% of cases when performed by an experienced surgeon. As with any operation, complications may occur – these include gland re-prolapse, infection, cyst formation and suture-related problems. The operation can be repeated if the gland re-prolapses; re-prolapse is more common in animals which have already had one failed operation prior to referral and in certain breeds such as the Mastiff.
If you have any queries or concerns, please do not hesitate to contact us.