Lagophthalmos is a condition in which blinking and eyelid closure are incomplete, leaving the eyeball exposed. The term originates from the Greek word “lagos” (hare), named after the habit of hares sleeping with their eyes open.
Exposure of the eyeball disrupts the tear film, leading to dry eye and corneal infection. In advanced cases, it can lead to corneal perforation and blindness. Conjunctival hyperemia and eye pain also occur 2).
Lagophthalmos is broadly classified into the following four types.
| Type | Pathophysiology | Representative Diseases |
|---|---|---|
| Paralytic | Decreased orbicularis oculi contraction | Facial nerve palsy (Bell’s palsy, after acoustic neuroma resection, cerebrovascular disease) |
| Cicatricial | Cicatricial contracture of the eyelid | After trauma, burns, or surgery |
| Mechanical | Inability to close eyelids due to proptosis | Thyroid eye disease, orbital tumor, high myopia |
| Physiological (nocturnal lagophthalmos) | No organic or functional abnormality | During sleep, habitual |
The most common cause is paralytic, among which facial nerve palsy (especially Bell’s palsy) accounts for the majority. In paralytic lagophthalmos, paralysis of the orbicularis oculi muscle causes the upper eyelid margin to be elevated with skin laxity (pseudoptosis), and the lower eyelid to become droopy or everted, resulting in incomplete eyelid closure.
Facial nerve palsy is accompanied by the following extraocular findings.
As for corneal findings, corneal epithelial damage due to incomplete eyelid closure is characterized by being compartmental in the lower part, with almost no epithelial damage above a certain height. When compartmental corneal epithelial damage limited to the lower part is observed, incomplete eyelid closure or nocturnal lagophthalmos should be strongly suspected.
| Severity | Findings | Management |
|---|---|---|
| Mild | Superficial punctate keratopathy (SPK) only | Conservative treatment (eye drops, ointment, taping) |
| Moderate | Corneal epithelial defect or ulcer formation | Aggressive conservative treatment; consider surgical indication |
| Severe | Risk of corneal perforation or deep corneal ulcer | Emergency surgery (e.g., tarsorrhaphy) |
Bell’s phenomenon (upward rotation of the eyes during sleep) normally protects the cornea, but when eyelid closure is severely incomplete, the lower cornea becomes exposed, leading to inferior corneal damage due to nocturnal lagophthalmos. Nocturnal lagophthalmos often presents with few daytime symptoms, with ocular symptoms appearing in the morning 2).
Paralytic (most common)
Bell’s palsy (idiopathic facial nerve palsy): Most common cause. Incidence of 20–30 per 100,000 people per year 1).
Ramsay Hunt syndrome: Reactivation of varicella-zoster virus. Prognosis is worse than Bell’s palsy.
Others: After acoustic neuroma surgery, cerebrovascular disease, myasthenia gravis, sarcoidosis, multiple sclerosis, congenital.
Cicatricial
Trauma/Burns: Scar contracture of the anterior lamella of the eyelid, including chemical burns.
Post-surgery: Anterior lamella scarring after eyelid surgery or cosmetic surgery.
Inflammatory diseases: Eyelid scarring due to Stevens-Johnson syndrome or ocular pemphigoid.
Mechanical
Thyroid eye disease (Graves’ disease): Severe proptosis can lead to inability to close the eyelids.
Orbital tumor/Orbital hematoma: Mechanical lagophthalmos due to forward displacement of the globe.
High myopia: Axial elongation may cause proptosis leading to lagophthalmos.
Physiological (nocturnal lagophthalmos)
Also present in healthy individuals: During sleep, voluntary eyelid closure is absent, and Bell’s phenomenon exposes the lower cornea.
Prevalence: Observed in a certain proportion of healthy individuals. Symptoms are more likely to become apparent in dry environments or with use of sleeping pills.
If the patient complains of morning eye pain or photophobia, suspect nocturnal lagophthalmos.
Risk factors for Bell’s palsy include diabetes, pregnancy, and immunodeficiency. Lagophthalmos frequently occurs after facial nerve palsy, and the risk of corneal complications increases with the severity of palsy10). In a study of 2,500 cases of Bell’s palsy, complete recovery within 6 months was reported in 71% of patients1).
The following assessments are performed for eyelid closure evaluation:
Detects sectoral epithelial damage in the lower cornea. Also used to assess the area of exposed cornea. Schirmer test is performed to evaluate concomitant dry eye.
The House-Brackmann (HB) classification 11) is used to assess the severity of facial nerve palsy.
| Grade | Findings | Severity |
|---|---|---|
| I | Normal | Normal |
| II | Mild dysfunction | Slight asymmetry at rest, good eye closure |
| III | Moderate dysfunction | Eye closure possible but with effort |
| IV | Moderately severe dysfunction | Incomplete eye closure, asymmetric movement |
| V | Severe | Barely moves, difficulty closing eye |
| VI | Complete paralysis | No movement, unable to close eye |
For HB grades IV–VI, active corneal protection and surgical treatment should be considered 6).
Paralytic:
Mechanical:
Cicatricial:
Even nocturnal lagophthalmos alone can cause corneal epithelial damage. Corneal protection is achieved by applying ophthalmic ointment or taping before sleep. If symptoms persist, an ophthalmology consultation is recommended. If eye pain or photophobia occurs in the morning, strongly suspect nocturnal lagophthalmos and confirm inferior corneal epithelial damage with fluorescein staining.
Eye drops and ophthalmic ointments:
Taping:
| Condition | Taping method |
|---|---|
| Mild (when eyelid opening is needed during the day) | Tape in two directions: lifting the eyebrow upward and pulling the lower eyelid upward and outward toward the ear. |
| Severe (nighttime or strong corneal epithelial damage) | After applying ophthalmic ointment, tape vertically from the upper eyelid to the lower eyelid while looking downward to achieve complete eyelid closure. |
Moisture chamber glasses: Attach a moisture chamber to the eyeglass frame to maintain humidity around the eyes and reduce corneal dryness.
Upper eyelid (orbicularis oculi muscle paralysis / incomplete eyelid closure):
Lower eyelid (ectropion/lagophthalmos):
Tarsorrhaphy:
Partial suturing of the eyelids laterally (lateral tarsorrhaphy) or medially to reduce the area of exposed ocular surface. Useful for corneal protection in the acute phase, performed temporarily or permanently. If recovery of facial nerve palsy is expected, reversible temporary tarsorrhaphy is chosen6).
Eyelid reconstruction (cicatricial/traumatic):
Treatment of underlying disease (mechanical):
In thyroid eye disease, symptomatic treatment with artificial tears and eye ointment stabilizes the ocular surface, and orbital decompression after the inflammatory phase resolves the root cause. For orbital tumors, tumor excision is curative.
Acute phase (within 72 hours of onset) pharmacotherapy:
Ophthalmologic management:
First, protect the cornea with frequent instillation of artificial tears and application of eye ointment before bedtime. Taping to assist eyelid closure is also effective. If corneal epithelial damage progresses, promptly consult an ophthalmologist. In Bell’s palsy, early administration of steroids and antiviral drugs is important for nerve recovery, and priority should be given to visiting an otolaryngologist or neurologist within 72 hours of onset.
It functions permanently, but rarely, plate migration or infection may occur, requiring reoperation. Platinum chains are said to have better flexibility and lower risk of migration compared to gold plates 12). Note that since it assists eyelid closure using gravity, its effect is reduced in the supine position (during sleep).
It varies greatly depending on the cause. In Bell’s palsy, 70–85% recover completely with appropriate treatment, but it usually takes 3–6 months 1). If there is no improvement after 6 months, surgical intervention is considered. For cicatricial or mechanical lagophthalmos, treatment of the underlying disease is fundamental, and spontaneous recovery is often not expected.
The facial nerve (cranial nerve VII) runs through the temporal bone, exits the stylomastoid foramen, and branches into multiple peripheral branches within the parotid gland. The orbicularis oculi muscle is innervated by the temporal and zygomatic branches, and its contraction closes the eyelid. In Bell’s palsy, edema and ischemia within the facial nerve canal are the main causes of nerve damage 7).
Paralytic: Facial nerve (VII) palsy → orbicularis oculi muscle paralysis → incomplete eyelid closure. In the upper eyelid, skin laxity occurs, giving the appearance of pseudoptosis. In the lower eyelid, drooping and ectropion occur, worsening the incomplete closure.
Cicatricial: Scar contracture of the anterior lamella (skin and orbicularis muscle) physically prevents eyelid closure. It may progress rapidly after thermal or chemical burns.
Mechanical: Proptosis prevents the eyelids from covering the eye. In thyroid eye disease, edema and fibrosis of orbital fat and extraocular muscles push the eyeball forward.
Nocturnal Lagophthalmos (Physiologic): Voluntary eyelid closure disappears during sleep, and physiologic upward eye rotation (Bell’s phenomenon) exposes the lower cornea. It becomes apparent when complete closure is not possible without voluntary orbicularis contraction.
Incomplete eyelid closure → tear film disruption → corneal dryness → epithelial damage (superficial punctate keratopathy) → epithelial defect → infection → corneal ulcer → corneal perforation. Even with normal Bell’s phenomenon, if incomplete closure is severe, the lower cornea is persistently exposed, leading to sectoral epithelial damage. Decreased tear secretion (due to lacrimal gland dysfunction from facial nerve palsy) further accelerates corneal damage 2, 6).
In Bell’s palsy, 70–85% recover completely with appropriate treatment (steroids + antivirals). If residual palsy persists for more than 6 months, surgical treatment for fixed paralytic lagophthalmos is considered. In thyroid eye disease, after symptomatic treatment during the inflammatory (active) phase, orbital decompression and eyelid surgery are performed during the non-inflammatory (stable) phase. Severe corneal exposure carries a risk of corneal perforation and may require emergency procedures such as tarsorrhaphy 6).
Nerve Reconstruction: For irreversible facial nerve palsy, nerve transfer such as masseter-to-facial nerve transfer has been reported. A comparison between the masseter nerve and hypoglossal nerve groups showed better recovery of spontaneous facial movement in the former 13). Crossface nerve graft (facial nerve to facial nerve anastomosis) is excellent for restoring symmetry of facial expression but requires time for nerve regeneration.
Platinum Chain Lid Loading: Developed as an improved version of the gold plate. Comparative studies show superior flexibility, less cosmetic discomfort during eyelid opening, and lower risk of migration 12).
Botulinum toxin injection: This method induces temporary ptosis by injecting botulinum toxin into the levator palpebrae superioris muscle, thereby assisting eyelid closure. It may be positioned as a temporary measure during the acute phase of Bell’s palsy.
Artificial nerve grafting / stem cell therapy: Basic research aimed at facial nerve regeneration is ongoing. Although not yet clinically applied, it is attracting attention as a future therapeutic strategy.
