Lagophthalmos

Lagophthalmos is incomplete closure of the eyelids, which leaves the cornea exposed during blinking or sleep. Nocturnal lagophthalmos occurs in about 20 percent of normal people and is only pathological when keratopathy results.

• Causes:
  • Facial nerve (VII) palsy (Bell palsy, trauma, tumours, surgery, herpes zoster oticus, Guillain-Barre syndrome).
  • Thyroid eye disease (proptosis and eyelid retraction).
  • Eyelid scarring, cicatricial ectropion, or previous blepharoplasty or ptosis surgery.
  • Proptosis from other causes (orbital tumours, high myopia), floppy eyelid, severe ptosis surgery, or a lid mass.
  • Coma and sedation (ventilated patients are at risk of exposure keratopathy).
  • Neuromuscular and congenital causes.
• Mechanism: exposure leads to tear film evaporation, epithelial damage, and a nonhealing corneal ulcer, which can perforate, with high risk when corneal sensation is reduced.

• Dryness, grittiness, redness, and tearing; morning pain with nocturnal lagophthalmos; blurred vision.
• Gap between the lids on gentle closure, measured in millimetres at the widest point; incomplete blink.
• Exposure keratopathy (inferior punctate keratopathy), conjunctival injection, and keratinisation in chronic disease.
• Bell phenomenon (upward rotation of the globe on attempted closure) is a protective reflex; absence increases risk.
• In facial palsy: lack of facial expression, brow ptosis, flat nasolabial fold, and lower lid ectropion.
• Complications: corneal ulcer, secondary infection, scarring, perforation, and vision loss.

• Measurement of the palpebral fissure and the lid gap on gentle closure and on sleep (observation or video), Bell phenomenon, and corneal sensation.
• Fluorescein and lissamine green staining of the cornea; tear break up time.
• Evaluation of the cause: neurological examination of cranial nerves, MRI of the brain and facial nerve, thyroid function tests and thyroid antibodies, orbital imaging, and examination of the lid for scars.
• Differential diagnosis: dry eye disease, ectropion, and floppy eyelid syndrome (which causes nocturnal lagophthalmos with papillary conjunctivitis, associated with obstructive sleep apnoea).

• Corneal protection comes first:
  • Preservative free lubricating drops every 1 to 2 hours by day and thick lubricating ointment (paraffin based) at night, or a gel at bedtime.
  • Moisture chamber goggles or polyethylene film, and taping the lids closed at night (hypoallergenic tape), with careful instruction.
  • Lid closure in the unconscious or ventilated patient (lubricant ointment every 4 hours and polyethylene covers).
  • Antibiotic ointment (chloramphenicol 1 percent four times daily) if there is an epithelial defect.
  • Punctal plugs help in aqueous deficiency but may worsen epiphora in facial palsy.
• Temporary measures: botulinum toxin A injected into the levator palpebrae superioris (2.5 to 5 units) to induce protective ptosis for 2 to 3 months, and temporary suture tarsorrhaphy.
• Facial nerve palsy: early steroids for Bell palsy (prednisolone 60 mg daily for 5 days then taper over 5 days) with aciclovir or valaciclovir, and surgical rehabilitation if recovery fails by 6 to 12 months: upper lid gold or platinum weight (0.8 to 1.6 g) to aid closure, lateral tarsorrhaphy, lower lid tightening or suspension, spring implants, and facial reanimation surgery.
• Thyroid eye disease: treat active inflammation (intravenous methylprednisolone 4.5 g cumulative over 12 weeks, or teprotumumab 10 mg/kg then 20 mg/kg every 3 weeks for 7 infusions), and once the disease has been stable for 6 months, lengthen the lids with upper lid Muller muscle or levator recession and lower lid retractor recession with a spacer graft.
• Cicatricial lagophthalmos: release of scars with skin grafts.
• Floppy eyelid syndrome: treat obstructive sleep apnoea with continuous positive airway pressure, and nocturnal eye shields.
• Follow up: frequent review (days to weeks) for corneal ulceration; urgent referral for corneal ulcer or reduced vision.
• Complications: exposure keratopathy, ulceration, perforation, and blindness.