Ocular microtremor (OMT) is a fixational eye movement that cannot be seen with the naked eye but is always present, even when the eye appears motionless/still. The link between OMT and brain function provides a strong rationale for investigation as there lies potential for its use as a biomarker in populations with neurological impairments. OMT frequency is typically 70-80Hz in healthy adults and research suggests that this will be reduced in those with neurological disease such as Parkinson’s Disease (PD). This study aims to examine OMT in people with PD compared to healthy older adults. This is an exploratory, observational study that will use a novel handheld device–The iTremor ONE, which has been developed to rapidly, non-invasively assess and evaluate OMT frequency. This device uses incident laser technology directed at the sclera. People with PD who meet the inclusion criteria will participate in a home-based assessment involving cognitive, motor (using the UPDRS-III) and OMT measures. With OMT as the primary outcome, assessment with the iTremor is quick, taking just three seconds to obtain a reading. People with PD will be invited into the laboratory to perform extensive cognitive assessments along with an assessment of balance, gait, and turning using wearable sensors. People with PD will be assessed both off, and on, their anti-parkinsonian medication following a 12 hour washout period. We will recruit 30 People with PD, 30 people with suspected PD and 30 age-matched healthy control participants for assessment of OMT. 20 People with PD will complete a test-retest reliability assessment at the same approximate time, exactly one week after their initial visit under the same conditions to explore consistency. This will be the first study of its kind to non-invasively investigate OMT frequency as a marker/monitor for PD with advanced technology that could be used within the clinic, laboratory, or home. Identifying OMT as a PD biomarker could better support clinical assessment, enabling improved provision of care to patients with advanced disease monitoring. Clinical trial registration: This trial is registered at clinicaltrials.gov (NCT06051877; September 2023).

Eye-movement assessment is a key component of neurological evaluation, offering valuable insights into neural deficits and underlying mechanisms. This narrative review explores the emerging subject of digital eye-movement outcomes (DEMOs) and their potential as sensitive biomarkers for neurological impairment. Eye tracking has become a useful method for investigating visual system functioning, attentional processes, and cognitive mechanisms. Abnormalities in eye movements, such as altered saccadic patterns or impaired smooth pursuit, can act as important diagnostic indicators for various neurological conditions. The non-invasive nature, cost-effectiveness, and ease of implementation of modern eye-tracking systems makes it particularly attractive in both clinical and research settings. Advanced digital eye-tracking technologies and analytical methods enable precise quantification of eye-movement parameters, complementing subjective clinical evaluations with objective data. This review examines how DEMOs could contribute to the localisation and diagnosis of neural impairments, potentially serving as useful biomarkers. By comprehensively exploring the role of eye-movement assessment, this review aims to highlight the common eye-movement deficits seen in neurological injury and disease by using the examples of mild traumatic brain injury and Parkinson’s Disease. This review also aims to enhance the understanding of the potential use of DEMOs in diagnosis, monitoring, and management of neurological disorders, ultimately improving patient care and deepening our understanding of complex neurological processes. Furthermore, we consider the broader implications of this technology in unravelling the complexities of visual processing, attention mechanisms, and cognitive functions. This review summarises how DEMOs could reshape our understanding of brain health and allow for more targeted and effective neurological interventions.

Background There is currently no pharmacological treatment for visuo-cognitive impairments in Parkinson’s disease. Alternative strategies are needed to address these non-motor symptoms given their impact on quality of life. Novel technologies have potential to deliver multimodal rehabilitation of visuo-cognitive dysfunction, but more research is required to determine their feasibility in Parkinson’s. Objective To determine the feasibility and preliminary efficacy of a home-based, technological visuo-cognitive training (TVT) intervention using a mobile application and exercise with stroboscopic glasses compared to non-technological care in people with Parkinson’s. Methods This 18-month, parallel, two-arm pilot trial took place between July 2021-December 2022. Participants were community-dwelling individuals with a diagnosis of Parkinson’s, aged over 50 years. Participants were randomly allocated to one of two active four-week interventions, TVT (n = 20) or standard care (SC) (n = 20). A physiotherapist delivered 8 home visits over 4 weeks, lasting 45–60 mins. Participants were evaluated at baseline and then on completion of the intervention. Primary outcomes were feasibility of the study design and intervention (recruitment/retention, adherence, assessment time scale, equipment and safety). Exploratory outcomes included assessments of cognitive, visual, clinical and motor function. (Blinding of participants was not possible due to the nature of the intervention) Results The recruitment rate was 60% (40/67), and the retention rate was 98% (39/40). Adherence to both arms of the intervention was high, with participants attending 98% of visits in the TVT group and 96% of visits in the SC group. 35% (9/20) of participants in the TVT group experienced mild symptoms associated with use of the stroboscopic glasses which included dizziness, queasiness and unsteadiness. There were minimal between group differences, with both interventions having positive effects on a variety of clinical, cognitive, and physical performance outcomes. Conclusions Our findings suggest that home-based TVT with a physiotherapist is feasible in people with Parkinson’s and could provide an alternative approach to addressing cognitive and motor dysfunction in this population. We make recommendations for future trials and invite ensuing studies to improve upon the design and utilise stroboscopic visual training and digital tools to investigate this emerging area of multimodal rehabilitation. This trial was prospectively registered at ISRCTN (registration number: ISRCTN46164906; https://doi.org/10.1186/ISRCTN46164906).