Prolapse of the third eyelid gland (cherry eye)

What it is

The gland of the third eyelid normally sits hidden at the base of the third eyelid. When the connective tissue that anchors it to the periorbita is weak, the gland slips up and protrudes over the free margin of the third eyelid, where it becomes exposed, inflamed and swollen. The condition is commonly known as "cherry eye". The cause is thought to be an inherited laxity of the gland's attachments.

Who it affects

Young dogs, usually under 2 years of age. Predisposed breeds include the English bulldog, French bulldog, Neapolitan mastiff, cane corso, cocker spaniel, beagle, shar-pei, Lhasa apso, shih tzu and Boston terrier. It is often bilateral, sometimes weeks or months apart.

Anatomy involved

The third eyelid (plica semilunaris conjunctivae) is a fold of conjunctiva at the medial angle of the eye, supported by a T-shaped cartilage. The gland of the third eyelid (glandula superficialis palpebrae tertiae) surrounds the base of the stem of that cartilage. Its ducts open on the bulbar surface of the third eyelid, among lymphoid follicles. Together with the lacrimal gland, it produces the aqueous part of the tear film; its contribution is large, which is why removing it predisposes to keratoconjunctivitis sicca.

Clinical signs

A smooth, pink to red, oval mass protruding from behind the third eyelid at the medial canthus. Mild ocular discharge and conjunctivitis are common; with time the exposed gland may become dry, ulcerated or fibrotic.

Diagnosis

The diagnosis is clinical. It should be distinguished from eversion of the cartilage of the third eyelid (a scroll-shaped fold of the third eyelid itself), from neoplasia of the third eyelid in older dogs and from prolapse of orbital fat. A Schirmer tear test is useful before and after treatment.

Treatment

Surgical replacement of the gland is the treatment of choice. The most widely used techniques create a pocket in the conjunctiva on the bulbar surface of the third eyelid and bury the gland in it (pocket technique), or anchor the gland to the periosteum of the orbital rim or to deep tissues. Recurrence is possible, especially in large and brachycephalic breeds, and may need a second procedure. Excision of the gland is contraindicated because it increases the risk of keratoconjunctivitis sicca later in life. Anti-inflammatory drops may reduce swelling but rarely achieve lasting reduction.