Distichiasis

Distichiasis is an accessory row of eyelashes growing from the openings of the meibomian glands, behind the normal lash line. The lashes are often thinner and shorter and may turn toward the cornea.

• Congenital distichiasis is autosomal dominant with variable penetrance, caused by mutations in FOXC2. It may be isolated or part of lymphoedema distichiasis syndrome (onset of lymphoedema of the legs around puberty, varicose veins, ptosis, cleft palate, congenital heart defects, and spinal extradural cysts).
• Acquired distichiasis follows chronic inflammation: Stevens-Johnson syndrome, ocular cicatricial pemphigoid, chemical burns, chronic blepharitis, and trauma, through metaplasia of the gland acini into pilosebaceous units.
• Many patients are asymptomatic; symptoms depend on lash stiffness and direction.

• Foreign body sensation, tearing, photophobia, redness, and blepharospasm in children, depending on the number and rigidity of lashes.
• A second row of lashes emerging from the meibomian orifices, in the upper or lower lids (more often lower), partially or completely.
• Punctate keratopathy, corneal erosions, and in severe cases ulceration, scarring, and vascularisation.
• Syndromic features: leg lymphoedema (typically from early adulthood), venous insufficiency, ptosis, cleft palate, cardiac anomalies, and spinal cysts causing neurological signs.

• Slit lamp examination shows lashes emerging from the meibomian gland orifices behind the grey line, with fluorescein staining of the corresponding cornea.
• Family history and evaluation for lymphoedema distichiasis syndrome: examination of the legs, venous Doppler, echocardiography, and spinal MRI if neurological signs.
• Genetic testing for FOXC2 mutation in familial or syndromic cases; counselling because the condition is dominantly inherited (50 percent transmission risk).
• Acquired disease: evaluation for ocular cicatricial pemphigoid (conjunctival biopsy), drug history, and chronic lid disease.
• Differential diagnosis: trichiasis, entropion, epiblepharon, and lid margin lesions.

• Asymptomatic patients and those with soft, non-irritating lashes: observation with lubrication (preservative free drops four times daily and ointment at night).
• Symptomatic lashes:
  • Epilation of the lashes gives short term relief (4 to 6 weeks), and repeated epilation may be used in children, but recurrence is rapid.
  • Definitive ablation of the follicles: electrolysis, argon laser photoablation, radiofrequency ablation, or cryotherapy (double freeze thaw to minus 20 degrees Celsius), with risks of depigmentation, notching, and recurrence.
  • Lid margin splitting with excision of the follicles (lamellar division and removal of the distichial lash roots) or a posterior lamellar graft for extensive disease.
  • Conjunctival bandage contact lens for chronic keratopathy.
• Acquired disease: treat the underlying inflammation (pemphigoid with systemic immunosuppression), and maintain ocular surface lubrication.
• Syndromic cases: compression stockings and lymphoedema care for leg swelling, cardiac assessment, and screening for spinal cysts.
• Children: early treatment prevents amblyopia from corneal scarring, and surgery under general anaesthesia may be needed for unmanageable symptoms.
• Follow up every 3 to 6 months for corneal staining.
• Complications: corneal ulceration, scarring, vascularisation, recurrence of lashes after ablation, and visual loss.