Prolapse of the Tear Gland of the Third Eyelid
Unlike humans (who only have two eyelids), dogs and cats have three. The third eyelid, technically called the nictitans or nictating membrane, arises from the inner corner of the eye and covers the eye diagonally as shown. The eye is lubricated by tear film, which consists of water, oil, and mucus. The oil comes from glands lining the outer eyelids, the mucus comes from glands in the conjunctiva (the pink part inside the eyelids), and the water comes from tear (or lacrimal) glands. Each eye has two glands: one just above the eye and one located in the third eyelid. The gland in the third eyelid is believed to produce a full 30 percent of the total tear film water, so it is important to maintain the function of this gland.
The lacrimal gland of the third eyelid is held in place by tissue fibers but some individuals have weaker fibers than they should so the gland protrudes. This protrusion is called a cherry eye. In the smaller breeds — especially Boston terriers, cocker spaniels, bulldogs and beagles — the gland of the third eyelid is not strongly held in place for genetic reasons. The gland prolapses (drops down) out to where the owner notices it as a reddened mass. Out of its normal position, the gland does not circulate blood properly, may swell, and may not produce tears normally.
Treatment: Replacing the Gland in its Proper Location
By far the best treatment for cherry eye is replacing the gland back into its proper location. There are two techniques for doing this. The traditional tucking method (also called tacking) used to be the most commonly performed. Here, a single stitch is permanently placed, drawing the gland back where it belongs.
In a newer surgical technique called imbrication, or pocketing, a wedge of tissue is removed from directly over the actual gland. This technique is more challenging. Tiny stitches that will eventually dissolve are used to close the gap so that the tightening of the incision margins pushes the gland back in place.
Sometimes both surgical techniques are used in the same eye to achieve a good replacement. Harmful complications from cherry eye surgery are unusual but recurrence of the cherry eye can happen. If it recurs, it is important to let your veterinarian know so that a second surgery, either with your veterinarian or an ophthalmologist, can be planned.
Expect some postoperative swelling after cherry eye repair but this should resolve and the eye should be comfortable and normal in appearance after about a week. If the eye appears suddenly painful or unusual in appearance, have it rechecked as soon as possible.
Treatment: Removing the Gland – NOT CONSIDERED ACCEPTABLE
Historically, the prolapsed gland was treated like a small tumor; it was simply removed. This was before the full significance of the gland was realized.
If the third eyelid’s tear gland is removed, it cannot be put back in place. If the other tear gland (the one above the eye) cannot supply adequate tears, not an uncommon phenomenon in older small breed dogs, then the eye becomes dry and uncomfortable. A thick yellow discharge results and the eye develops a blinding pigment covering for protection. This condition is called simply dry eye or more scientifically keratoconjunctivitis sicca and daily medical treatment is required to keep the eye both comfortable and visual. Not only is dry eye uncomfortable, its treatment is often frustrating and time-consuming and there is expense involved. If left untreated, the eye can become blind. We would like the dog to maintain the greatest amount of tear-producing tissue possible, thus removing the gland for cosmetic reasons is not an acceptable treatment method.