Anisocoria refers to a condition where the pupils of the eyes are of unequal size. While normally both pupils are expected to be of the same diameter, in anisocoria, they differ significantly. This asymmetry often results from damage or dysfunction within the nervous pathways that control pupil size. Under normal circumstances, pupils react to light changes: they constrict (become smaller) in bright light and dilate (become larger) in dim light or darkness. However, if one pupil suddenly becomes noticeably larger or smaller than the other, it is crucial to seek immediate medical evaluation from an ophthalmologist. This condition can sometimes indicate underlying serious health issues and may lead to severe long-term complications if left unaddressed.