5 The eyelid functions to protect the cornea and globe, regulate light entering the eye, aid in the distribution of the tears across the cornea and to the nasolacrimal drainage system, and contribute part of the precorneal (preocular) tear film (from meibomian glands). Neonatal ophthalmia is an infection that occurs beneath closed eyelids in young animals with physiologic ankyloblepharon (Figure 5.1). It can be associated with delayed or incomplete opening of the pup’s eyelids at 12–14 days postnatal. Bacterial conjunctivitis is common and can be exacerbated in cats if there is a concurrent infection with feline herpesvirus type 1 (FHV‐1). The conjunctival sac distends and purulent material may begin to extrude through an opening between the eyelid margins if one exists. Early treatment with topical antibiotics and surgical opening of the palpebral fissure is recommended before corneal ulceration develops. Figure 5.1 Ankyloblepharon and neonatal ophthalmia in a Shetland Sheepdog puppy. Note the marked swelling of the eyelids. Purulent exudate is escaping at an opening in the medial ankyloblepharon. Agenesis of the eyelids occurs most commonly in cats; however, it is occasionally present in dogs and other species (Figure 5.2). Most often the coloboma affects the lateral aspects of the upper eyelids. Lack of lid margin often results in trichiasis, superficial keratitis, and persistent irritation. Surgical correction is recommended if these signs persist. Surgical procedures to treat lid agenesis involve filling the missing lid with sliding or pedicle eyelid skins flaps from the lower ventral lateral eyelid or the lateral commissure of the mouth. Other extra‐ and intraocular defects are often present concurrently, and can impact the overall prognosis. Figure 5.2 Agenesis of the lateral upper eyelid in a Miniature Poodle puppy. Lack of eyelid margin in the affected area has resulted in trichiasis and local keratoconjunctivitis. Dermoids or choristomas affect the lids infrequently, and more often involve the bulbar conjunctiva, limbus, or even the nictitating membrane (Figure 5.3). They can be inherited in the German Shepherd, St. Bernard, and Dalmatian breeds. Lid dermoids are characterized as a focal lid mass covered with long coarse hair. Histologically, they consist of connective and adipose tissues as well as normal skin tissues. Surgical correction requires excision of the entire dermoid and reconstruction of the defect. Figure 5.3 (A) Dermoid of the palpebral conjunctiva and lower eyelids in a Cairn Terrier. Note the long and coarse hairs which cause considerable discomfort. (B) Dermoid of the upper eyelid in a young Golden Retriever. Structural abnormalities of the eyelids represent the largest group of lid diseases in the dog. Blepharophimosis, blepharostenosis, or micropalpebral fissure occur in certain breeds, such as the Chow Chow, English Bull Terrier, Shetland Sheepdog, and Kerry Blue Terrier (Figure 5.4). The globe is usually normal, but sometimes microphthalmia is concurrent. Entropion often develops with micropalpebral fissures, and can result in corneal damage or persistent irritation, so surgical correction is recommended. Often, the area of the lids affected is breed‐specific and bilateral. Figure 5.4 Blepharophimosis or a reduced palpebral fissure in a Chow Chow puppy. The shortened eyelids usually develop entropion and require surgical correction (lateral canthoplasty). The entropion has resulted in corneal and conjunctival irritation and a mucopurulent discharge. Euryblepharon or macropalpebral fissure is divided clinically into two types. Figure 5.5 (A) Pekingese dog has euryblepharon or an enlarged palpebral fissure which results when the eyelids are longer than normal. The result is greater exposure of the cornea (note the central scar from a previous ulcer) and conjunctiva (which is visible nearly 360° around the cornea). (B) Euryblepharon in a Shih Tzu. Note the dramatic amount of scleral show. This animal is at risk for proptosis. Figure 5.6 Clumber Spaniel with very prominent “V” notch in the central lower eyelid. Treatment of euryblepharon is surgical; however, the choice of surgical procedure depends on the breed and specific anatomy of the individual. Most cases will benefit from some sort of lid shortening or stabilizing procedure. Entropion is a very common lid disease in the dog wherein the eyelid margin inverts to cause contact of haired skin with the bulbar conjunctiva and cornea. Entropion usually requires surgical correction. The sometimes profound discomfort (blepharospasm) that results aggravates further the original entropion and results in spastic entropion. Pain generated by the eyelid hairs touching the cornea and conjunctiva can often account for more than 50% of the entropion. The real danger with entropion is corneal disease, which manifests with ulcerations and scarring. Entropion is often exhibited in young and growing puppies (such as the Chinese Shar Pei) but can self‐correct as the animal grows. Permanent surgical correction should be minimal or postponed until the puppy has approximated its adult size lest over‐correction occur. As entropion can affect the upper lid, lower lid, and lateral canthus, surgical correction varies according to the amount and position of the defect. Entropion is generally believed to be inherited as an autosomal dominant, but breeding studies are lacking. Entropion is often breed‐related and occurs in the Chow Chow, Shar Pei, St. Bernard, English Bulldog, English and American Cocker Spaniels, English Springer Spaniel, Labrador Retriever, Bull Mastiff, Great Dane, Irish Setter, Norwegian Elkhound, and Toy and Miniature Poodles, among others (Figure 5.7). Figure 5.7 (A) Entropion appears to be inherited in many breeds; in the Norwegian Elkhound the entropion is usually confined to the lateral and lower eyelid, and may self‐correct in young dogs. (B) Lateral canthal and lower entropion in a young Labrador Retriever. (C) Lateral lower eyelid entropion in a Shar Pei. Note the temporal keratitis. (D) Chinese Shar Pei puppy with nearly 360° entropion. At this age, maintaining the eyelids open using tacking sutures is recommended. (E) Entropion affecting upper and lower eyelids of a mature Chinese Shar Pei. Surgical correction may also include a face lift (removal of one or more of the facial skin folds). Ectropion is less common than entropion in the dog, and results when the eyelid margins are everted from the eye, exposing the ventral conjunctiva. Ectropion can be developmental or secondary to inflammation, trauma, surgery, or aging. Exposure of the conjunctiva and cornea results in persistent inflammation and irritation of the conjunctiva, impaired tears dynamics, epiphora, and exposure keratitis (often seen as corneal vascularization and pigmentation). Surgical correction of ectropion is recommended if the secondary corneal and conjunctival disease cannot be resolved medically or if the abnormality increases in severity. Most lower eyelids with ectropion are longer than normal, and most corrective surgeries involve some shortening of the lower lid (Figure 5.8). Figure 5.8 (A) Severe bilateral ectropion in Bloodhound with chronic discomfort and secondary bacterial conjunctivitis. (B) Severe cicatricial ectropion in a Bracco Italiano following surgery to correct entropion. The combination of entropion and ectropion can occur in the larger breeds of dog. Certain breed standards require a “diamond‐shaped” palpebral fissure, a prominent nictitating membrane, and/or a drooping low eyelid. These standards result in persistent eye disease throughout life, and sometimes corrective surgery is required. The breed standards should be re‐evaluated and updated to modern societal, ethical, and medical levels to eliminate these unnecessary eyelid abnormalities and animal discomfort. Breeds with combined entropion–ectropion include Bloodhound, St. Bernard, Newfoundland, Clumber Spaniel, and Bull Mastiff (Figure 5.9).
Canine Eyelids
Congenital and Developmental Disease
Breed‐Associated Eyelid Disorders
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