Trichiasis

Trichiasis is acquired misdirection of eyelashes toward the globe so that they rub on the cornea and conjunctiva. The lid margin position is normal, which differentiates it from entropion.

• Causes:
  • Trachoma (the commonest cause worldwide and a leading cause of blindness in endemic areas), by scarring of the tarsal conjunctiva.
  • Chronic blepharitis and meibomian gland disease, herpes zoster, trauma and burns, chemical injury, ocular cicatricial pemphigoid, Stevens-Johnson syndrome, previous lid surgery, and chronic inflammation.
  • Idiopathic, particularly in older adults.
• Consequences: chronic corneal abrasion, ulceration, scarring, vascularisation, and visual loss; secondary infection.
• Related terms: aberrant lashes from the lash line (trichiasis) versus an extra row from the meibomian glands (distichiasis) and lashes from a displaced lid margin (entropion).

• Foreign body sensation, redness, tearing, photophobia, pain on blinking, and blurred vision.
• Lashes directed against the globe, either a few or many, often with associated lid margin scarring and thickening, madarosis, and tarsal conjunctival scarring in trachoma.
• Fluorescein staining shows punctate or linear epithelial erosions in a pattern that matches the lash position, usually inferior or superior.
• Complications: corneal ulcer, pannus (vascularisation), opacity, and visual loss.
• In trachoma: a trachomatous scarring with a distorted lid margin and lashes touching the cornea.

• Slit lamp examination of the lashes at the lid margin with the patient looking in various gazes, lid eversion, and fluorescein staining of the cornea.
• Differentiate from entropion, distichiasis, epiblepharon, and lashes pushed by a lid lesion.
• Assess for causes: lid margin inflammation, cicatricial conjunctival disease (conjunctival biopsy for pemphigoid), history of trachoma or herpes zoster, and burns.
• Count lashes and measure the area of scarring to plan treatment (fewer than 5 lashes versus more than 5, and extent).

• Immediate: epilation of the offending lashes with fine forceps under the slit lamp provides relief but the lashes regrow within 4 to 6 weeks; lubricants and antibiotic ointment for abrasions (chloramphenicol 1 percent four times daily for 5 to 7 days).
• Ablative therapy for few, localised lashes (fewer than 5):
  • Electrolysis (a fine needle with low current down the follicle).
  • Radiofrequency ablation, argon laser photoablation (50 to 100 micrometre spot, 0.2 second, 200 mW), or cryotherapy (double freeze thaw cycle to minus 20 degrees Celsius for 20 to 30 seconds under local anaesthesia). Cryotherapy risks depigmentation, lid notching, and loss of adjacent lashes. Recurrence is about 20 to 40 percent.
• Surgical therapy for many lashes (5 or more) or trachomatous trichiasis:
  • Bilamellar tarsal rotation (the preferred surgery in trachoma) or posterior lamellar tarsal rotation, with a horizontal incision of the tarsus and rotation of the lid margin outward.
  • Lid margin or wedge resection for a localised cluster; lid splitting with follicle excision.
  • Mucous membrane graft for severe cicatricial changes.
  • Recurrence after surgery is 10 to 30 percent, higher in severe disease and with less experienced surgeons.
• Treat underlying disease: trachoma (azithromycin 20 mg/kg single oral dose, maximum 1 g, with community treatment), pemphigoid (systemic immunosuppression), blepharitis, and herpes zoster.
• Patient education: do not self-pluck without follow up; return urgently with corneal pain or reduced vision.
• Follow up: 1 week after surgery and at 3 to 6 months for recurrence.
• Complications: corneal ulceration, scarring, recurrence, lid notching, and overcorrection.