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970 Third Eyelid Abnormalities/Protrusion

Third Eyelid Abnormalities/Protrusion Client Education
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RISK FACTORS
BASIC INFORMATION
surface, causing keratitis (rare)
• Prolapsed gland of the third eyelid: concur- ○ Inversion of the cartilage toward the ocular
Definitions rent follicular conjunctivitis may induce ○ Evidence of conjunctivitis, including
• Prolapsed gland of the third eyelid: dorsal prolapse mucoid ocular discharge, epiphora,
displacement and prolapse of the gland from • Bilateral third eyelid protrusion: cats living lymphoid follicles and hyperemia
its normal position at the base of the third in multi-cat households; association with ○ May have concurrent prolapsed gland of
eyelid gastrointestinal disease, diarrhea, feline the third eyelid
• Everted cartilage of the third eyelid: a leukemia virus (FeLV), and a toravirus-like • Protrusion of the third eyelid
malformed leading edge of the third eyelid agent ○ One or both third eyelids extend more
that rolls outward • Third eyelid protrusion secondary to ocular dorsally and temporally than normal.
• Protrusion of the third eyelid: a third eyelid pain and enophthalmos: consider keratocon- ○ ± Evidence of ocular pain: blepharospasm
that is resting in an elevated or more dorsal junctivitis, corneal ulceration, uveitis, and ○ ± Other signs of Horner’s syndrome
position, covering the ocular surface glaucoma ○ ± Exophthalmos or enophthalmos
• Atypical pannus: localized proliferative • Third eyelid protrusion secondary to exoph- • Atypical pannus
inflammation of the third eyelid found in thalmos or enophthalmos ○ Various surface irregularities and pigment
German shepherds and greyhounds (p. 748) • Follicular conjunctivitis: high exposure to loss on leading edge of third eyelid
• Third eyelid neoplasia: any neoplastic growth allergens (e.g., field trial dogs) • Third eyelid gland neoplasia
originating from the gland or conjunctiva ○ Various findings, depending on tumor
of the third eyelid ASSOCIATED DISORDERS type and location
Prolapsed gland of the third eyelid: ■ Adenomas and adenocarcinomas arise
Synonyms • Conjunctivitis (pp. 199 and 200) from the gland on the posterior aspect
• Third eyelid: membrana nictitans, nictitating Third eyelid protrusion: of the third eyelid.
membrane • Secondary to ocular pain and resultant ■ Hemangiomas, hemangiosarcomas (red
• Bilateral third eyelid protrusion: Haw’s enophthalmos masses), and squamous cell carcinoma
syndrome • Exophthalmos or enophthalmos (p. 716) (pinkish/white masses) most often arise
• Prolapsed gland of the third eyelid: cherry • Otitis and nasopharyngeal polyps from the anterior surface or leading
eye • Horner’s syndrome margin of the third eyelid.
• Everted cartilage: scrolled cartilage, bent • Rabies ○ Mandibular lymph node enlargement may
cartilage, protruding third eyelid cartilage • Tetanus be present.
tips • Cannabis intoxication
• Atypical pannus: plasmoma • Dysautonomia Etiology and Pathophysiology
• Other systemic illness (e.g., cytauxzoonosis) • Prolapsed gland of the third eyelid: possible
Epidemiology Third eyelid inflammation: polygenic inheritance; may occur secondary
SPECIES, AGE, SEX • Atypical pannus to loosening of retinacular attachments of
• Prolapsed gland of the third eyelid: young • Follicular conjunctivitis the gland to the shaft of the third eyelid
dogs and cats, most often less than 2 years • Keratoconjunctivitis: eosinophilic, cats cartilage
of age • Everted cartilage of the third eyelid: disparate
• Everted cartilage of the third eyelid: congenital Clinical Presentation growth rate of posterior aspect of third
or early developmental malformation HISTORY, CHIEF COMPLAINT eyelid cartilage relative to the anterior
• Third eyelid protrusion secondary to ocular Common layperson descriptions: aspect
pain, enophthalmos, and exophthalmos: dogs • Droopy eyelids (describing ptosis and third • Protrusion of the third eyelid (four patho-
and cats of any age (pp. 705 and 716) eyelid protrusion seen in Horner’s syndrome) physiologic causes)
• Third eyelid gland neoplasia: most common • Membrane covering the eye (describing third ○ Active retraction of the globe (enophthal-
in older dogs and cats eyelid protrusion) mos) by retractor bulbi contraction from
• Follicular conjunctivitis: dogs and cats typi- ocular pain, leading to passive protrusion
cally < 18 months of age (pp. 199 and 200) PHYSICAL EXAM FINDINGS of the third eyelid
• Prolapsed gland of the third eyelid ○ Disruption of smooth muscle tone on
GENETICS, BREED PREDISPOSITION ○ A smooth, round, pink or red protrusion the orbital cone from Horner’s syndrome,
• Prolapsed gland of the third eyelid: most over the leading edge of the third eyelid. infection (rabies, tetanus), dysautonomia
common in beagles, American cocker Size varies significantly based on breed or toxin (cannabis intoxication), leading
spaniels and brachycephalic breeds, especially and chronicity. to enophthalmos resulting in passive
the English bulldog; Burmese cats are ○ Evidence of conjunctivitis, including protrusion of the third eyelid
predisposed mucoid discharge, epiphora, lymphoid ○ Imbalance of orbital volume secondary
• Everted cartilage of the third eyelid: inherited follicles, and hyperemia to enophthalmos (pain or loss of orbital
in German shorthair pointers. giant-breed ○ ± Low Schirmer tear test values contents), exophthalmos (e.g., retrobulbar
dogs are predisposed, including Great Danes, • Everted cartilage of the third eyelid neoplasia, orbital cellulitis), microphthal-
Newfoundlands, mastiff breeds, and St. ○ The entire leading edge of the third eyelid mos, or phthisis bulbi leading to passive
Bernard dogs; reported in Burmese and scrolls anteriorly (rostrally) away from the protrusion of the third eyelid
British blue cats ocular surface due to a bend in the shaft ○ Voluntary control of third eyelid protru-
• Atypical pannus: German shepherds, grey- of the cartilage. sion (only seen in cats) leading to active
hounds, and others ○ Anterior (rostral) protrusion of the protrusion of the third eyelid
• Follicular conjunctivitis: primarily large-breed cartilaginous tips of the leading edge of • Atypical pannus: immune-mediated
dogs (especially retrievers) the third eyelid (less common) • Neoplasia of the third eyelid

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