Distichia are abnormal eyelid hairs that arise from a gland in the eyelid known as the Meibomian gland and exit through its opening at the eyelid margin. This gland opens close to the cornea, and these hairs usually contact the cornea.
Trichiasis refers to eyelid hairs that arise from a normal location, but are directed toward and are in contact with the cornea.
Ectopic cilia are hairs that also arise from the Meibomian glands, but exit through the inside surface of the eyelid and poke against the cornea.
Distichia and trichiasis are not always significant, but may cause irritation, tearing, corneal pigmentation and scarring, or corneal ulceration. Ectopic cilia are usually a more severe eyelash abnormality because they often cause corneal ulceration.
Eyelash abnormalities may occur in any breed. Trichiasis is most common in short-nosed dogs such as the shih tzu, Lhasa apso, Pekingese, Maltese, and pug. Distichia are commonly seen in cocker spaniels and golden retrievers. Ectopic cilia occur sporadically in most animal breeds. Eyelash conditions are usually seen in young animals.
Clinically significant trichiasis is treated with surgical removal of the offending hairs or freezing (cryosurgery) of the affected area to destroy the hair follicles. Clinical distichia and ectopic cilia are treated with destruction of the hair follicle by electrolysis, freezing or a combination of these procedures. Complete permanent removal of all the eyelid distichia is unlikely.
The goal is to decrease clinical signs of the majority of abnormal hairs allowing a functional eyelid and healthy cornea. Occasionally more than one surgery is necessary to remove offending hairs. Medical treatment and surgery may be necessary in some patients to improve symptoms.
For more information on this subject, speak to the veterinarian who is treating your pet.