{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T13:00:56Z","timestamp":1785416456330,"version":"3.56.0"},"reference-count":51,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2026,6,11]],"date-time":"2026-06-11T00:00:00Z","timestamp":1781136000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100001288","name":"Parkinson\u2019s Foundation","doi-asserted-by":"publisher","award":["PF-FBS-1898"],"award-info":[{"award-number":["PF-FBS-1898"]}],"id":[{"id":"10.13039\/100001288","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100001288","name":"Parkinson\u2019s Foundation","doi-asserted-by":"publisher","award":["PF-CRA-2073"],"award-info":[{"award-number":["PF-CRA-2073"]}],"id":[{"id":"10.13039\/100001288","id-type":"DOI","asserted-by":"publisher"}]},{"award":["PF-FBS-1898"],"award-info":[{"award-number":["PF-FBS-1898"]}],"id":[{"id":"https:\/\/ror.org\/05mx85j86","id-type":"ROR","asserted-by":"publisher"}]},{"award":["PF-CRA-2073"],"award-info":[{"award-number":["PF-CRA-2073"]}],"id":[{"id":"https:\/\/ror.org\/05mx85j86","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Pupil response may be a useful biomarker in Parkinson\u2019s disease (PD) due to links with autonomic function and cognitive load. However, research has focused on static tasks, missing functional demands during real-world activities like walking. Methods: We recruited 38 people with PD and 16 healthy controls who walked for 2 min under single- and dual-task conditions while wearing mobile eye-tracking glasses (Tobii Pro Glasses 2, 100 Hz). Pupil response outcomes (velocity, size, difference between eyes) were extracted alongside gait characteristics from inertial sensors. Known groups validity compared PD and controls; convergent\/divergent validity examined relationships with cognitive, visual, clinical, and gait measures. Results: People with PD had significantly altered pupil constriction\/dilation velocity (p = 0.01), a larger difference between their left and right pupils (p = 0.04), and a larger mean and minimum pupil size (p \u2264 0.01) compared to controls during walking. Pupil response correlated with cognitive function (JLO, CLOX1, TMTB), visual acuity, disease severity (MDS-UPDRS-III), and gait characteristics in both groups. No dual-task effects were observed. Conclusions: Pupil response during walking demonstrates known groups and convergent validity, indicating potential as a clinical biomarker for PD. Following this initial study, more research is required to further validate pupil response in PD (e.g., analytical validation and testing within real-world ecologically valid environments).<\/jats:p>","DOI":"10.3390\/s26123711","type":"journal-article","created":{"date-parts":[[2026,6,11]],"date-time":"2026-06-11T12:14:58Z","timestamp":1781180098000},"page":"3711","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Clinical Validation of Pupil Response During Walking in Parkinson\u2019s Disease"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6887-8739","authenticated-orcid":false,"given":"Lisa","family":"Graham","sequence":"first","affiliation":[{"name":"Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle NE1 8ST, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7128-9452","authenticated-orcid":false,"given":"Rodrigo","family":"Vitorio","sequence":"additional","affiliation":[{"name":"Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle NE1 8ST, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4049-9291","authenticated-orcid":false,"given":"Alan","family":"Godfrey","sequence":"additional","affiliation":[{"name":"Department of Computer and Information Sciences, Northumbria University, Newcastle NE1 8ST, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Martina","family":"Mancini","sequence":"additional","affiliation":[{"name":"Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rosie","family":"Morris","sequence":"additional","affiliation":[{"name":"Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle NE1 8ST, UK"},{"name":"Northumbria Healthcare NHS Foundation Trust, North Shields NE27 0QJ, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6846-9372","authenticated-orcid":false,"given":"Samuel","family":"Stuart","sequence":"additional","affiliation":[{"name":"Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle NE1 8ST, UK"},{"name":"Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA"},{"name":"Northumbria Healthcare NHS Foundation Trust, North Shields NE27 0QJ, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1002\/mds.25150","article-title":"Parkinson\u2019s disease: Evidence for environmental risk factors","volume":"28","author":"Kieburtz","year":"2013","journal-title":"Mov. 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