Scientific reports
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The pupillary light reflex (PLR) describes the response when light hits the retina and sends a signal (cranial nerve II) to the Edinger-Westphal Nucleus which via cranial nerve III results in pupillary constriction. The Neurological Pupil indexTM (NPi) and pupil constriction velocity (CV) are two distinct variables that can be observed and measured using a pupillometer. We examine NPi and CV in 27,462 pupil readings (1,617 subjects). ⋯ The remaining 30.9% revealed that one or both PLR had either a normal NPi with slow CV, or abnormal NPi with brisk CV. Brisk CV does not rule out an abnormal PLR; slow CV does not rule in abnormal PLR. Practitioners should consider these implications when interpreting pupillometry readings.