Internal ophthalmoplegia refers to paralysis of the __________.

• A. Eyelids
• B. Pupil
• C. Extraocular muscles
• D. Retina

Answer: (B)

Internal ophthalmoplegia means the dysfunction of the intrinsic eye muscles inside the globe that are controlled by the parasympathetic fibers of the oculomotor nerve. These muscles include the sphincter pupillae, which constricts the pupil, and the ciliary muscle, which adjusts the lens for accommodation. When these intrinsic muscles are paralyzed, the pupil cannot constrict properly, leading to a dilated pupil and impaired near vision due to loss of accommodation. The pupil is the structure affected because it directly reflects the parasympathetic control disrupted in internal ophthalmoplegia. External movements of the eye involve the extraocular muscles, which is a different topic, and the retina isn’t the target of this parasympathetic dysfunction.