Page 1338 - Problem-Based Feline Medicine

66. The cat with an abnormal

third eyelid

Michael E. Bernays

KEY SIGNS
● Abnormal prominence of third eyelid.
● Focal or generalized swelling of third eyelid.
● Erythemia, chemosis.
● Eyelid lacerations.
● Ocular discharge.

MECHANISM?
● Abnormalities of third eyelid appearance usually result from abnormalities in eyelid innerva-
tion, especially of the autonomic sympathetic nerves, or inflammation or neoplasia involving
the conjunctiva of the third eyelid.
WHERE?
● Third eyelid cartilage.
Conjunctiva covering the third eyelid.
Gland of the third eyelid.

WHAT?
● The most common cause of altered third eyelid appearance is autonomic nervous system disease
especially sympathetic neuropathy. Neoplasia and inflammatory disease is occasionally seen.

QUICK REFERENCE SUMMARY
Diseases causing an abnormal third eyelid

WHERE?
THIRD EYELID
METABOLIC
● Third eyelid prominence related to severe weight loss* (p 1137)
Occurs secondary to loss of orbital fat and enophthalmos (caudal globe retraction).

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