Pupil cycle time: as indicator of visual pathway dysfunction in multiple sclerosis

To evaluate the value of pupil cycle time (PCT) as an indicator of optic nerve dysfunction in patients with multiple sclerosis (MS), 42 patients with MS and 35 control subjects were included to the study. Patients with MS with a history of ON were accepted as group 1, without a history of ON as group 2 and healthy control subjects as group 3. Groups were compared with Chi-square and one-way ANOVA tests. Correlations of PCT results with age, best corrected visual acuity, duration of MS, visual field (VF) test, visual evoked potential (VEP) latans, retinal nerve fiber layer (RNFL), and ganglion cell layer–inner plexiform layer (GCL–IPL) thicknesses were analyzed. Mean PCT was 1286.4 ± 357.8 ms in group 1, 1021.3 ± 102.3 ms in group 2, and 872.5 ± 69.4 ms in group 3 (p < 0.001). Moderate-to-significant correlations were found between PCT measurements and duration of MS, VF test, VEP latans, RNFL, and GCL–IPL thicknesses. PCT might be an alternative method to evaluate the optic nerve function in patients with MS.