Exposure Keratopathy

Exposure keratopathy is damage to the corneal epithelium and stroma caused by inadequate lid closure, tear evaporation and desiccation.

• Causes:
  • Facial nerve palsy (lagophthalmos), Bell palsy, cerebellopontine angle tumours.
  • Thyroid eye disease and other causes of proptosis, lid retraction.
  • Cicatricial lid disease, ectropion, lid coloboma, post-blepharoplasty.
  • Reduced consciousness: ICU patients with sedation, coma, neuromuscular blockade (incidence 20 to 40 percent without eye care), general anaesthesia (corneal abrasion).
  • Nocturnal lagophthalmos (sleeping with lids incompletely closed), floppy eyelid syndrome, severe dry eye.
  • Reduced blink in Parkinson disease.
• Inferior third of the cornea (exposed in primary position) is most affected, and Bell phenomenon is protective.

• Redness, grittiness, burning, tearing, worse on waking.
• Inferior punctate epithelial erosions that coalesce into an epithelial defect; conjunctival injection and keratinisation in the interpalpebral zone.
• Reduced vision, corneal haze and vascularisation in chronic cases.
• Complications: sterile and infectious ulceration, stromal melt, perforation, scarring.
• Lagophthalmos (gap on gentle lid closure), lid retraction, ectropion, absent Bell phenomenon.

• Slit lamp with fluorescein showing inferior or interpalpebral punctate staining.
• Measure lagophthalmos (millimetres of gap on gentle closure, and forced closure), blink rate and completeness, lid position, Bell phenomenon, corneal sensation, proptosis (exophthalmometry).
• Identify the cause: cranial nerve VII examination, neuroimaging if palsy is unexplained, thyroid function tests, medication review.

• Prophylaxis in unconscious and sedated patients: preservative free lubricating drops every 2 hours plus lubricating ointment (carbomer gel or paraffin ointment) every 4 to 6 hours, gentle lid closure with soft paper tape (not on the cornea), polyethylene film (cling film) or moisture chamber goggles; avoid manual lid taping with adhesive on the lashes.
• Mild disease: preservative free tears four to eight times daily, ointment at night, lid taping at night, humidification, treat blepharitis.
• Moderate disease: punctal occlusion, bandage or scleral contact lens, moisture goggles, autologous serum 20 percent, and antibiotic ointment when an epithelial defect is present (chloramphenicol 1 percent four times daily).
• Persistent defect or ulcer: tarsorrhaphy (temporary with sutures, permanent lateral), botulinum toxin A to the upper lid levator (2.5 to 5 units, lasting 8 to 12 weeks), amniotic membrane, and treat infection with fortified antibiotics (cefuroxime 5 percent with gentamicin 1.5 percent hourly, or fluoroquinolone monotherapy) after cultures.
• Definitive correction of the cause: gold or platinum eyelid weight implants (0.8 to 1.6 g) for facial palsy, lower lid tightening (lateral tarsal strip), spacer graft for lid retraction, orbital decompression for proptosis, treatment of thyroid disease.
• Review within 24 to 48 hours of any epithelial defect, and monitor for infection.