Background
Distichiasis is a rare disorder defined as the abnormal growth of lashes from the orifices of the meibomian glands on the posterior lamella of the tarsal plate (see following image).
This picture demonstrates distichiasis of the lower lid. From Principles and Practice of Ophthalmology by Jakobiec. Two types of distichiasis can be identified, acquired and congenital. In the acquired form, most cases involve the lower lids. Lashes can be fully formed or very fine, pigmented or nonpigmented, properly oriented or misdirected. The congenital form is dominantly inherited with complete penetrance. It can be isolated or associated with ptosis, strabismus, congenital heart defect, or mandibulofacial dysostosis. This defect may be related to the epithelial germ cells failure to differentiate completely to meibomian glands, instead they become pilosebaceous units.
Pathophysiology
Distichiasis can affect the lower and upper lids (see following images). When these abnormal lashes come in contact with the cornea, they may cause severe irritation, epiphora, corneal abrasion, or even corneal ulcers.
This picture demonstrates distichiasis of the lower lid. From Principles and Practice of Ophthalmology by Jakobiec.
This picture demonstrates distichiasis of the upper lid. From Ophthalmic Plastic Surgery: Prevention and Management of Complications by Dortzbach. Epidemiology
Frequency
United States
Distichiasis is a rare disorder.
Race
Distichiasis has been seen in all ethnic backgrounds.
Sex
This condition shows no sex discrimination.
Age
Distichiasis has been seen in all ages.
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