Objective: To investigate the value of pupillometric parameters according to the progress of Parkinson’s disease (PD).

Background: Pupil light reflex is known to be associated with a parasympathetic nervous system. Recent studies in patients with Alzheimer’s disease and PD suggesting that the pupil constriction velocity is decreased in these patients, reflecting cholinergic deficit. However, there is a lack of research on the association between pupil light reflex and disease progression in PD patients.

Method: We performed pupilometer testing on 148 patients with PD from September to December 2019. The patients with an eye disease such as glaucoma which may affect results of pupilometer test were excluded from the recruitment. Of the 141 patients, except for the first 17 diagnosed with PD, 124 patients who were already receiving dopaminergic treatment were divided into two groups according to the severity of PD. Neurological examination and pupilometer test of all patients were performed in ON state. Hoehn and Yahr stages 1 and 2 were defined as early groups and 3 to 5 as late groups. We performed age and sex matched 2:1 propensity score to compensate the effect of age on pupil light reflex. Mean value of pupilometer parameters such as pupil size, minimum diameter of pupil, percent change of pupil, constriction velocity, maximum constriction velocity, latency of constriction, and dilation velocity were measure and compared between the two groups.

Results: After propensity score matching, 64 patients were classified as early group and 32 patients were classified as late group. The late group had longer disease duration (6 years VS 4 years, p = 0.010) and higher levodopa equivalent dose (392 ± 217 VS 641 ± 297, p < 0.001) than the early group. The constriction velocity (2.29 ± 0.62 VS 1.89 ± 0.57, p = 0.002) and maximum constriction velocity (3.36 ± 0.87 VS 2.79 ± 0.80, p = 0.003) were significantly faster in the early group than in the late group. Pupil size was larger in the early group than in the late group (3.97 ± 0.62 VS 3.60 ± 0.72, p = 0.015).

Conclusion: In this study, the pupillary contraction rate slowed down in proportion to the severity of disease progression and motor symptoms. This shows the possibility of observing the disease progression and severity of PD by measuring the constriction velocity of pupil using pupilometer.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/analysis-of-pupillometer-results-according-to-motor-symptoms-severity-in-parkinsons-disease-patients/