Abnormal Dynamic Pupillometry Relates to Neurologic Disability and Retinal Axonal Loss in Patients With Multiple Sclerosis

PURPOSE: To assess alterations in quantitative dynamic pupil responses to light in relation to neurologic disability and retinal axonal loss in patients with multiple sclerosis (MS). METHODS: Twenty-five patients with relapsing-remitting MS and 25 healthy subjects were included in this cross-sectional study. Pupillary responses were measured with an infrared dynamic pupillometry unit, and peripapillary retinal nerve fiber layer (RNFL) thickness was measured with spectral-domain optical coherence tomography. Neurologic disability was assessed by the Expanded Disability Status Scale (EDSS). Patients with a history of optic neuritis (ON) within 6 months were excluded. Only the right eyes were assessed, except in 11 patients with a history of unilateral ON in whom both eyes were further analyzed to evaluate the effect of previous ON. RESULTS: The initial pupil diameter (P = 0.003) and pupil contraction amplitude (P = 0.027) were lower in patients with MS compared with healthy controls. Initial pupil diameter correlated with EDSS score (ρ = −0.458; P = 0.021), and RNFL correlated with contraction latency (ρ = −0.524; P = 0.007). There were no significant differences in any of the pupil parameters between eyes with and without a history of ON, and between the ON and fellow eyes of the 11 patients with previous unilateral ON. CONCLUSIONS: Dynamic pupillometry reveals significant alterations in pupillary light reflex responses associated with neurologic disability and retinal axonal loss, independent of previous ON. TRANSLATIONAL RELEVANCE: Dynamic pupillometry is a simple, noninvasive tool that may be useful in detecting autonomic dysfunction in patients with MS.