Etiology
Trichiasis refers to an abnormal misdirection of lashes, often turning inward against the eye, in the absence of entropion (Figure 2).
- Cicatricial lash problems generally arise from acute or chronic inflammation
- Most common acute causes
- Viral infection (herpes zoster, herpes simplex, vaccinia)
- Chemical burns, especially alkali
- Trauma
- Radiation
- Surgery
- Cryotherapy
- Most common chronic causes
- Blepharitis (Staphylococcus, seborrhea, rosacea, etc.)
- Trachoma
- Chronic viral infection
- Conjunctival shrinkage (pemphigoid, Stevens-Johnson syndrome)
- Topical medications
- Idiopathic inflammation
- Establishing the correct diagnosis is important and may affect prognosis and therapy
- If untreated, pemphigoid can lead to blindness.
- Unless patients are treated with immunesuppressants, pemphigoid can worsen with surgical insult.

Figure 2. Trichiasis. Image courtesy Thomas M. Lietman, MD.
History
- Duration of symptoms
- Presence of oral or skin lesions or herpetic outbreaks
- Previous lash removal treatments
- Previous eyelid trauma or surgery
- Foreign travel or residence
- History of radiation treatment to periocular area
- Current or prior use of glaucoma or other eyedrops
- Use of cosmetic eyelash enhancing preparations
Clinical features
- Inward directed lashes: Note location and extent of misdirected lashes.
- Note mild in-turning of eyelid margin.
- Tarsal fibrosis or cicatrized conjunctiva
- Evidence of prior trauma or surgery
- Document related corneal changes.
- Eyelid lesions distorting lash orientation
Testing
- Cultures can be useful for infectious processes.
- Conjunctival biopsy with basement membrane studies for mucous membrane pemphigoid