Which of the following is NOT a typical etiology of exposure keratopathy?

• A. Thyroid eye disease
• B. Cavernous sinus thrombosis
• C. Floppy eyelid syndrome
• D. Bell's palsy

Answer: (B)

Exposure keratopathy occurs when the cornea isn’t adequately protected by the eyelids or tear film, so it dries and breaks down. The classic culprits are conditions that directly impair eyelid closure or tear maintenance: facial nerve weakness causing lagophthalmos (as in Bell’s palsy), proptosis and lid malposition from thyroid eye disease, and eyelid laxity seen in floppy eyelid syndrome. Cavernous sinus thrombosis, while it can cause orbital signs like proptosis and restricted eye movements, is not a typical direct cause of exposure keratopathy. Its issues arise from infection-related orbital involvement and cranial nerve problems rather than lid closure failure or tear film disruption, so it’s not a standard etiologic factor for exposure keratopathy.