Which statement about ectropion is NOT true?

• A. It is commonly caused by Horner's syndrome
• B. It is due to a loss of orbicularis oculi muscle tone
• C. The most common etiology is involutional changes
• D. It commonly leads to inferior SPK

Answer: (A)

Ectropion is outward turning of the lower eyelid away from the globe, usually because the lid support laxifies with age or due to loss of tone in the muscles and tendons that pull the lid in and maintain position. The commonest cause is involutional changes—age-related weakening of the orbicularis oculi and lateral canthal tendon. Paralytic ectropion can occur when the orbicularis oculi muscle loses tone, such as from facial nerve impairment, allowing the lid to eversion. Cicatricial changes from scarring can also pull the lid outward. Horner’s syndrome, on the other hand, does not typically cause ectropion; it mainly produces ptosis with miosis due to sympathetic denervation and is not a common driver of lower lid eversion. When the lid is exposed, tear film distribution is disrupted and the inferior cornea and sclera can develop exposure keratopathy, seen as inferior superficial punctate keratitis.