Pupil light reflex dynamics in Parkinson's disease

Panagiota Tsitsi; Mattias Nilsson; Josefine Waldthaler; Gustaf Öqvist Seimyr; Olof Larsson; Per Svenningsson; Ioanna Markaki

doi:10.3389/fnint.2023.1249554

Pupil light reflex dynamics in Parkinson's disease

Front Integr Neurosci. 2023 Aug 31:17:1249554. doi: 10.3389/fnint.2023.1249554. eCollection 2023.

Authors

Panagiota Tsitsi^{1

2}, Mattias Nilsson³, Josefine Waldthaler^{1

2}, Gustaf Öqvist Seimyr³, Olof Larsson⁴, Per Svenningsson^{1

2

5}, Ioanna Markaki^{1

2}

Affiliations

¹ Department of Clinical Neuroscience, Neuro, Karolinska Institutet, Stockholm, Sweden.
² Center for Neurology, Academic Specialist Center, Stockholm, Sweden.
³ Department of Clinical Neuroscience, Eye and Vision, Karolinska Institutet, Stockholm, Sweden.
⁴ Division of Aging Research Center, Karolinska Institutet, Stockholm, Sweden.
⁵ Department of Neurology, Karolinska University Hospital, Stockholm, Sweden.

Abstract

Introduction: Visual disturbance is common symptom in Parkinson's disease (PD), and defective pupil light reflex (PLR) is an anticipated contributing factor that may be associated to the presence of autonomic dysfunction, which is a common non-motor feature of PD. Studies investigating the intercorrelation between PLR and dysautonomia in PD are limited.

Methods: The aim of this study was to investigate differences of PLR parameters, measured by eye-tracker, between patients with PD, with and without signs of dysautonomia, and healthy controls (HC). In total, 43 HC and 50 patients with PD were recruited and PLR parameters were measured with Tobii Pro Spectrum, during a long (1,000 ms) and a short (100 ms) light stimulus. Presence of orthostatic hypotension (OH) was used as proxy marker of dysautonomia. Linear mixed-effects model and non-parametric comparative statistics were applied to investigate differences among groups.

Results: Peak constriction velocity was slower in PD compared with HC, after adjustment for age and sex in the mixed model, and the difference was greater in the subgroup of PD with OH (unadjusted). Dilation amplitude and velocity were also gradually slower in HC vs. PD without OH vs. PD with OH (unadjusted for confounders). In the mixed model, age was significant predictor of dilation response.

Discussion: Our results support previous observations on defective PLR in PD, evaluated with eye-tracker, and show a possible association with autonomic dysfunction. Further studies with more patients and rigorous evaluation of autonomic dysfunction are needed to validate these findings.

Keywords: Parkinson’s disease; dysautonomia; eye movements; eye tracking; pupil reflex.

Grants and funding

The study was funded by Vinnova, Sweden’s Innovation Agency (grant number: 2017-02317; early detection of Alzheimer’s and Parkinson’s disease based on eye-tracking and AI).