Chapter 1 Eyelid
The eyelids are composed of skin, eyelid muscles, eyelid glands (particularly the meibomian glands), and the palpebral conjunctiva, which lines the inner surface of the eyelids. The eyelids are affected by conditions that affect skin elsewhere on the body and a variety of anatomic abnormalities, as well as conditions that involve the conjunctiva and eyeball. Many eyelid abnormalities seen in dogs are breed related (e.g., distichia, entropion, and ectropion). Inflammatory diseases (e.g., blepharitis) may be associated with more widespread dermatitis. Various tumors may affect the eyelids in older animals and are illustrated in this chapter. Because the integrity of the eye may be affected by eyelid disease, careful observation and accurate diagnosis are important.
Figure 1-1 An Australian shepherd with a dermoid and eyelid agenesis of the lateral lower eyelid and conjunctiva. A dermoid is an occurrence of normal, haired skin in an abnormal location. Dermoids can be found on eyelid margins, conjunctiva, and corneas. Eyelid agenesis is the absence of normal eyelid in part of the palpebral fissure.
Figure 1-3 Right eye of cat in Figure 1-2. The upper eyelid agenesis involves most of the eyelid and lateral canthus—the most common location for eyelid agenesis in cats. Pigment is present on the cornea as a result of chronic exposure and because hair has come in contact with the cornea. The defect is corrected by the grafting of skin and conjunctiva to fill the defect. A mature cataract is present and is an unrelated problem.
Figure 1-2 Left eye of an older domestic shorthair cat with bilateral eyelid agenesis. The upper eyelid agenesis involves most of the eyelid and lateral canthus. Pigment is present on the cornea (arrow) as a result of chronic exposure and hair contact. A mature cataract is present and is an unrelated problem.
Figure 1-4 A-B A, Right eye of a cat with bilateral upper eyelid agenesis. Most of the upper eyelid is involved. B, Postoperative view. Skin from the lower eyelid has been rotated into the defect on the upper eyelid and lined with conjunctiva from the nictitans.
Figure 1-5 Distichiasis in a Pekingese. Distichia are cilia that exit from the openings of the meibomian glands at the eyelid margin. This dog has fine, delicate distichia in both the lower and the upper eyelids. Such hairs often cause a dog no problems. Excess tearing occasionally results from distichia. In rare cases distichia causes corneal ulcers. If treatment is necessary, electroepilation or cryosurgery can be used to remove the hairs permanently.
Figure 1-12 Small pigmented papilla on the conjunctival surface of the upper eyelid of a 10-year-old golden retriever. The dog had a history of a very painful eye and a nonhealing ulcer. The tip of an ectopic cilium was present in this papilla and protruded through the conjunctiva at the time of surgical removal. Ectopic cilia are abnormally positioned eyelid hairs that exit the conjunctival surface of the eyelid. They cause great discomfort and corneal ulcers that do not heal. Usually these cilia are found in young dogs but, as this case illustrates, can occur in dogs of all ages.
Figure 1-14 Lateral entropion of upper and lower eyelids in a German shorthaired pointer. Entropion is the rolling in of an eyelid. Haired skin then comes in contact with the corneal surface, which leads to chronic corneal ulcers and scarring. In this dog the eyelid disease has caused corneal ulceration, neovascularization, and granulation.
Figure 1-15 A-B A, Left and B, right eyes of a dog with entropion of the right eye. The entire length of the eyelid margin is seen in the left eye, but in the right eye the lateral part of the eyelid is not seen. Lateral eyelid hairs contact the cornea, causing ocular irritation, retraction of the globe, and protrusion of the third eyelid.