Exposure Keratopathy

Exposure keratopathy results from inadequate corneal protection by the eyelids — whether from lagophthalmos (incomplete lid closure), reduced blink rate, or proptosis. The inferior and interpalpebral cornea are most vulnerable. Without the protective blink reflex and adequate lid closure, the corneal epithelium desiccates, breaks down, and becomes susceptible to infection. Severity ranges from superficial punctate keratopathy to frank corneal ulceration.

Exposure keratopathy is common in hospitalized patients (particularly those in intensive care), patients with facial nerve palsy, thyroid eye disease, and following periocular surgery. Nocturnal lagophthalmos — incomplete lid closure during sleep — is underrecognized and may be present in up to 20% of the general population.

The corneal epithelium requires the tear film and periodic blinking for hydration and oxygen delivery. Inadequate lid closure exposes the inferior and interpalpebral cornea to desiccation, evaporation, and mechanical trauma. Reduced blink rate (as in Parkinson's disease, prolonged screen use, or sedation) similarly reduces tear film renewal. Proptosis (as in thyroid eye disease) increases the exposed corneal surface area. The resulting epithelial breakdown creates a portal for infection.

Inferior and interpalpebral superficial punctate keratopathy (SPK) is the earliest sign. Patients may report burning, foreign body sensation, and photophobia — though sensation may be reduced in severe cases. Corneal staining with fluorescein in the inferior third or interpalpebral zone is characteristic. Advanced cases develop frank epithelial defects, stromal infiltrates, and ulceration. Nocturnal lagophthalmos may present with symptoms that are worst upon awakening.

Management is directed at restoring corneal protection. Preservative-free lubricating drops (frequent daytime use) and lubricating ointment at night are foundational. Moisture chamber goggles or scleral lenses provide sustained corneal hydration. Taping the lids closed at night addresses nocturnal lagophthalmos. Underlying causes must be addressed: facial nerve palsy may require gold weight implantation or lateral tarsorrhaphy; thyroid eye disease requires systemic management and orbital decompression in severe cases. Bandage contact lenses protect the epithelium in acute settings.

Monitor corneal staining and epithelial integrity at each visit. Patients with active epithelial defects require frequent follow-up. Corneal sensation should be assessed — coexisting neurotrophic keratopathy significantly worsens prognosis.