Third eyelid Flashcards
3rd eyelid shape
T-shaped hyaline or elastic cartilage skeleton covered by conjunctiva
What species have hyaline 3rd eyelids
Ruminants Dogs
What species have elastic 3rd eyelids
horse pig cat
What percentage of the aqueous portion of the tear film does the 3rd eyelid contribute
35%
What causes movement of the 3rd eyelid
contraction of the extrinsic muscles of the eye that retract the globe
What species can move their 3rd eyelid
Cat
Function of 3rd eyelid (4 of them)
Protection of cornea Production of aqueous portion of precorneal tear film Distribution of tear film Limited immunological activity
Encircling 3rd eyelid
Seen in cocker spaniels Surgery almost never necessary
Congenital diseases of the 3rd eyelid
*Encircling 3rd eyelid* Pigmentation Dermoids Eversion of the cartilage
Acquired diseases
Prolapse of the gland Eversion or inversion of cartilage Protrusion of third eyelid Follicular conjunctivitis Neoplasia Plasma cell infiltration Foreign bodies
Treatment for prolapse of the gland
prolapse gland is surgically replaced never remove 3rd eyelid
Eversion or inversion or cartilage
Usually cosmetic, not a clinical problem
Etiologies of protrusion of 3rd eyelid (8 of them)
Decreased orbital mass Decreased ocular mass Denervation Ocular pain encephalitis Conjunctivitis Idiopathic
Should you remove the 3rd eyelid
no
Follicular conjunctivitis
common in dogs Persistent mucoid discharge with hyperplastic follicles