Unequal Pupils indicate which of the following?

• A. Normal finding
• B. Visual impairment due to refractive error
• C. Mild head trauma without symptoms
• D. Possible neurological emergency

Answer: (D)

Unequal pupils point to disruption of the neural control of the iris, which is a red flag for potential brain or nerve pathology. The pupil’s size and reaction depend on a balance between parasympathetic input (constriction via the oculomotor nerve) and sympathetic input (dilation). If one pupil is larger and not reacting normally to light, this can indicate a problem such as a compressive or traumatic injury affecting the brainstem or cranial nerves, or raised intracranial pressure with possible herniation. Because such findings can reflect a serious neurological emergency, they require urgent evaluation and monitoring.

Visual impairment due to refractive error does not typically change pupil size, and mild head trauma without symptoms is unlikely to produce a new, concerning anisocoria. Some people have normal, harmless differences in pupil size (physiologic anisocoria), but new or asymmetric pupillary responses are the key warning sign.