Incomplete eyelid closure, also known as lagophthalmos or "rabbit eye," refers to an inability of the upper and lower eyelids to fully close, leading to partial exposure of the eyeball. It is most commonly associated with facial nerve paralysis, trauma, thyroid-associated ophthalmopathy, and orbital tumors causing exophthalmos. In some individuals, a gap in the palpebral fissure may occur during sleep, which is referred to as physiological incomplete eyelid closure.
Clinical Manifestations
In mild cases, the upward reflex movement of the eyeball during eyelid closure (Bell's phenomenon) ensures that only the inferior bulbar conjunctiva remains exposed, which can lead to conjunctival congestion and dryness. Severe incomplete eyelid closure, however, results in corneal exposure, which can cause exposure keratitis and, in extreme cases, corneal ulceration. In most patients, the eyelids fail to make close contact with the eyeball, preventing the lacrimal puncta from properly connecting to the lacrimal lake, leading to excessive tearing (epiphora).
Diagnosis
Diagnosis is readily established based on the characteristic clinical signs of the eye.
Treatment
Treatment should primarily target the underlying cause. For example, cases related to cicatricial ectropion require surgical correction.
Prompt intervention is necessary to protect the cornea. Mild cases can be managed by applying antibiotic ointment to the conjunctival sac during sleep or using a moisture chamber to protect the cornea. In severe cases, tarsorrhaphy (eyelid margin fusion surgery) may be performed.