Patients with facial nerve paralysis need close monitoring to avoid visual complications from ocular surface exposure. Photo: James Heilman, MD. Click image to enlarge.

Ophthalmic involvement in facial nerve palsy occurs secondary to loss of orbicularis function, which results in an inability to close the eyelids. This exposed ocular surface is prone to increased tear evaporation and surface desiccation with epithelial breakdown. A recent study, published in the journal Orbit, analyzed the degree of ocular morbidity in terms of severe visual impairment, ocular surface exposure and associated risk factors in a large cohort of patients with facial nerve palsy, along with characteristics of any ocular manifestation. The researchers found that eyes with lagophthalmos, poor Bell’s phenomenon and facial nerve palsy of neoplastic etiology have a higher risk of ocular surface exposure.

The study reviewed the ocular data of all consecutive patients with facial nerve palsy (n=1,870) presenting to an eyecare network over the past 10 years. The researchers evaluated risk factors associated with severe visual impairment (best-corrected visual acuity <20/200) and ocular surface exposure at presentation.

The etiology of facial nerve palsy was classified as surgical, neoplastic, traumatic, congenital or idiopathic. Neoplastic cases included facial nerve palsies secondary to head and neck tumors or resection of these tumors. Surgical cases included those after parotidectomy or ear surgeries. The amount of lagophthalmos, presence of ectropion and ocular surface exposure (punctate epithelial erosions, corneal epithelial defects, corneal ulcer/perforation, corneal scar with erosions) were also recorded.

The prevalence of severe visual impairment among patients was 15%, while 47% overall had ocular surface exposure at the first presentation. The following were found to be independent risk factors for developing severe visual impairment when compared with eyes with no ocular surface exposure: the presence of corneal scar (28% vs. 10.2%; OR: 3.05), corneal ulcer (12.9% vs. 2.3%; OR: 4.67), older age at presentation (OR: 1.02), >10mm lagophthalmos (OR: 8.7), male sex and duration of facial nerve palsy (OR: 1.00).

Of the eyes with ocular surface exposure, 8.4% had a corneal ulcer, and 1.2% were perforated, with the rest having epithelial defects (12.9%), punctate keratopathy (59.0%) and corneal scar with punctate erosions (27.9%). Patients with neoplastic etiology (OR: 2.39), lagophthalmos (OR: 2.25) and poor Bell’s phenomenon (OR: 1.8) had a twofold risk for developing ocular surface exposure.

“Careful attention should be paid to facial nerve palsies due to neoplastic etiologies that are at higher risk of developing ocular surface exposure,” the researchers concluded in their paper. “The longer duration of facial nerve palsy and eyes with ocular surface exposure are at risk of visual impairment; hence, monitor these patients regularly.”

Singh S, Das AV, Ali MH. Ocular involvement in facial nerve paralysis: risk factors for severe visual impairment and ocular surface exposure in 1,870 patients. Orbit. July 8, 2022. [Epub ahead of print].