NOT a common etiology associated with entropion?

• A. Bell's palsy
• B. Involutional changes
• C. Trachoma
• D. OCP

Answer: (A)

Entropion happens when the eyelid margin turns inward, causing lashes to rub against the eye. The common causes fall into a few categories: involutional (age-related) changes that lead to lid laxity and inward pull of the margin; cicatricial scarring from diseases or infections that contract the lid and pull it inward; and less often spastic or mechanical factors. Involutional changes are a typical, age-related cause because the tissues around the eyelids thin and the canthal tendons loosen, allowing the lid to turn in. Cicatricial etiologies, such as trachoma or ocular cicatricial pemphigoid, create scarring that contracts and drags the lid margin inward, producing entropion.

Bell's palsy, a facial nerve palsy, more commonly leads to loss of eyelid tone and outward turning of the lid (ectropion) due to weakness of the orbicularis oculi muscle, rather than inward turning. So while Bell's palsy affects eyelid position, it does not typically cause entropion, making it the NOT common etiology among the options.