Describe the ocular management of facial nerve palsy.

The Eye in Facial Nerve Palsy

• The facial nerve supplies orbicularis oculi, so its paralysis abolishes lid closure and blinking and the eye is left exposed. The threat is to the cornea, and it is the ophthalmic responsibility in a condition otherwise managed by others
• The three mechanisms OF corneal damage.
• The factors that determine risk, and which must be assessed at the first visit:
• Bell’S phenomenon — the reflex upward rolling of the globe on attempted closure, which protects the cornea. A poor Bell phenomenon transforms the risk, and should be tested by holding the lids apart and asking the patient to close
• Corneal sensation — if the fifth nerve is also involved, as after acoustic neuroma surgery or in leprosy, the eye is both unprotected and anaesthetic, so the patient does not feel the damage. This combination is the most dangerous in the whole subject
• Tear production, which may also be reduced if the lesion is proximal to the greater petrosal nerve
• The expected duration — a Bell palsy expected to recover in weeks is managed differently from a permanent palsy after tumour surgery
• Causes — bell palsy (idiopathic, and much the commonest, with 85% recovering); RAMSAY hunt syndrome (herpes zoster of the geniculate ganglion, with vesicles in the ear and a worse prognosis); acoustic neuroma and its surgery; parotid tumour and surgery; trauma; stroke; leprosy, which is of particular importance in India and characteristically produces a patchy palsy with corneal anaesthesia; Guillain-Barre; Lyme disease; and sarcoidosis
• Distinguish upper from lower motor neurone — an upper motor neurone lesion spares the forehead (because of bilateral cortical representation) and the eye is far less at risk; a lower motor neurone lesion affects the whole side
• Management, in ascending order:
• Intensive lubrication — preservative-free drops hourly by day and ointment at night, which is the single most important measure
• Taping the lids closed at night, horizontally rather than vertically, and a moisture chamber or clingfilm shield
• Botulinum toxin to the levator to induce a temporary protective ptosis where the cornea is threatened and recovery is expected
• A gold or platinum weight implanted in the upper lid, which restores closure by gravity, is reversible and is cosmetically excellent
• Lower lid tightening (lateral tarsal strip) and medial canthoplasty for the ectropion