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274 Distichiasis/Ectopic Cilia/Trichiasis

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DISTICHIASIS/ECTOPIC CILIA/TRICHIASIS Distichiasis in a dog. Note the clusters of aberrant hairs
located along the upper and lower eyelid margins and arising from the meibomian ducts. These hairs were the
cause of a superficial corneal ulcer and required surgical removal.

Initial Database freeze/thaw cycle is effective for large
Complete ophthalmic exam (p. 1137): numbers of distichiae.
• Schirmer tear test (normal > 15 mm/min ○ Electrolysis is useful for single or low
DISTICHIASIS/ECTOPIC CILIA/TRICHIASIS in dogs, varies in cats) numbers of cilia; tedious procedure with
Distichiasis in a dog. Note the numerous long, aberrant • Fluorescein dye application increased risk of tissue damage.
hairs along the upper and lower eyelid margins and • Intraocular pressure (normal: 10-20 mm Hg) ○ Carbon dioxide laser removal is tedious,
arising from the meibomian gland ducts. These hairs • Examination of the eyelid margin and with increased risk of tissue damage
were an incidental finding, and because they caused palpebral conjunctiva with magnification ○ Resection from the conjunctival surface;
no clinical signs, no treatment was warranted. and a good light source effective for single or multiple cilia
• Examination of the cornea ○ Eyelid splitting techniques: not recom-
(see Genetics and Breed Predisposition mended; risk for postoperative eyelid
above) Advanced or Confirmatory Testing deformities and regrowth of hairs
○ Older dogs develop acquired trichiasis Examination with 5× to 10× magnification is Ectopic cilia:
secondary to ptosis and entropion that often required to visualize ectopic cilia. Ectopic • Usually requires surgical treatment
results from loss of muscle tone and orbital cilia are often the same color as the haircoat. • En bloc resection of aberrant cilia, including
fat The conjunctiva may be pigmented adjacent to associated conjunctiva and meibomian gland
○ Trichiasis is most commonly seen with the cilia or mucus may be trapped by the cilia. with a scalpel blade or 2-3 mm biopsy punch;
entropion, prominent nasal folds, and allow to heal by second intention
medial canthal hairs (eyelids and caruncle). TREATMENT • Surgical removal is usually successful, but
new cilia or regrowth is possible.
DIAGNOSIS Treatment Overview Trichiasis
The goals of treatment are to eliminate the ocular • Conservative management may be effective
Diagnostic Overview irritation to determine whether distichiasis, for minor ocular irritation.
• Distichiasis should be suspected on identifying trichiasis, or ectopic cilia is responsible for the ○ Clip hairs short to prevent ocular contact.
conjunctivitis or ulcerative and/or nonulcer- clinical signs of ocular disease and to remove • Variable surgical therapies, depending on
ative keratitis. Distichiae are confirmed when the offending cilia or direct the cilia away from location of trichiasis
adventitious lashes are observed originating the globe. Distichiasis and/or trichiasis without ○ Medial canthal trichiasis may be corrected
from the meibomian glands (no magnification signs of ocular irritation do not require treat- by permanent medial canthoplasty (pocket
necessary in most cases). ment. Depending on complexity of condition or Wyman techniques) or cryotherapy.
• Ectopic cilia should be suspected in dogs and number of offending hairs or cilia, consider ○ Nasal fold trichiasis may require resection
with acute blepharospasm and epiphora with referral to veterinary ophthalmologist. of prominent nasal folds.
signs of focal ulcerative and/or nonulcerative ○ Trichiasis associated with ptosis (drooping
keratitis; confirmation requires magnification Acute General Treatment upper eyelid) may be corrected by a Stades
to identify cilia emerging from the palpebral Distichiasis: procedure.
conjunctiva. • Usually does not produce clinical signs, and ○ Trichiasis associated with eyelid agenesis
• Trichiasis should be suspected in dogs no treatment is required. in cats may be corrected by cryotherapy
with conjunctivitis or ulcerative and/or • Hairs regrow in 4-5 weeks with mechanical until kitten is older for permanent surgery
nonulcerative keratitis when normal eyelid/ epilation/plucking, but this may be done to (e.g., rotational flap).
facial hair is directed toward and contacts determine significance of distichiae in corneal
the conjunctiva or corneal surface. irritation or disease. Chronic Treatment
• If clinical signs are present, consider treat- For recurrence, repeat treatment may be
Differential Diagnosis ment (under general anesthesia) required.
• Trichomegaly (excessively long eyelashes) ○ Before removal, manual expression of
• Other causes of blepharospasm, including the meibomian glands is attempted; this Possible Complications
corneal ulceration, conjunctivitis, uveitis, pushes hidden hairs from the glands. • The most common complication for all
epiphora ○ Cryotherapy along the palpebral surface conditions is recurrence.
• Entropion of the meibomian glands using a double • Postoperative eyelid scarring ± entropion

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