Fixate to find balance: visual fixation retraining for adults with visually induced dizziness

The intervention will be delivered over a four-week period and will include the following phases: a baseline assessment, a two-week active intervention phase, a one-week washout period, and a final post-intervention assessment. All participants will attend three clinical sessions at New Zealand Dizziness and Balance Centre (NZDBC): • Session 1 (Week 1): Baseline assessment and first intervention session • Session 2 (Week 2): Second intervention session • Session 3 (Week 4): Post-intervention assessment Each clinical session in weeks 1, 2, and 4 will last approximately 60 minutes, including rest periods. The study investigators and a trained research assistant will always be present during the clinical sessions. All interventions will be delivered by Shobika Ravindran who is a practicing clinician with four years of clinical experience and Dr Usman Ghani, a biomedical engineer and post doctoral research fellow. The experimental setup consists of a projector screen (Brateck Lumi), a mobile eye tracker device -Tobii Pro Glasses 3 and Gait&Balance smartphone application (G&B App) loaded on a smartphone. The projector screen will be positioned 3.5 metres in front of the participant to present the visual tasks used in the experiment. Visual fixations will be recorded using a mobile eye-tracking device, while postural sway metrics will be captured via the G&B app. The eye tracker provides immediate, live data following each recording session. In parallel, we will also use a low-cost portable EEG amplifier to assess cognitive workload (i.e. brain activity) during the intervention. The intervention will involve five visually stimulating tasks, adapted from a previous study conducted by our research team (Chaudhary et al., 2022 - ACTRN12619000254190). These tasks are specifically designed to elicit eye movements within visually complex environments. During each task, a single letter "X" will be projected onto the screen positioned in front of the participant, appearing in a random sequence across five distinct backgrounds that progressively increase in visual complexity. In line with prior research, a six-second threshold will be used as a cut-off to determine progression through the intervention task conditions. To minimise the risk of symptoms such as nausea or dizziness, the sequence of tasks will follow a fixed order rather than being randomised. The intervention task conditions are as follows: 1. Single letter on a neutral white background 2. Single letter on a small black and white checkered background 3. Single letter on a medium black and white checkered background 4. Single letter on a large black and white checkered background 5. Single letter on a complex 2-dimensional visual background Participants will be instructed to fixate their gaze on the centre of the projected target letter "X" for the entire duration of each task, which will last approximately five minutes, including setup time. Each task will be displayed for a total of 10 seconds. In Week 1, the task will be repeated three times, increasing to five repetitions in Week 2. Following the clinical sessions in Week 1 and Week 2, participants will be provided with a personalised home exercise programme to complete over the remainder of each week. This programme will focus on the intervention task that the participant found most challenging i.e., the task in which they did not achieve the six-second cut-off score. For example, if a participant is unable to meet the cut-off score in Task 3 (single letter on a medium black-and-white checkered background), that task will be assigned as their home-based exercise to retrain visual fixations. The anticipated duration of the home exercises is approximately 15 minutes per day for 7 days. Participants will receive the following materials to complete the home exercise programme: • An exercise workbook (instruction manual) • An exercise log sheet to track rehab progress • A large, printed banner displaying the exercise task to be completed • A piece of string to help replicate the 3.5-metre distance used in the clinical setting • A stopwatch to record the duration of task To support adherence and optimise engagement, a mid-week telephone consultation will be conducted to participants to clarify any questions/instructions and address any concerns they may have in relation to the home exercises. Following completion of the active intervention phase and washout period, participants will return to the NZDBC clinic at the start of Week 4 for a post-intervention assessment of visual fixation, postural control parameters and cognitive workload during tasks. During this session, participants will repeat the baseline assessments, complete the Dizziness Handicap Inventory (DHI) and the Visual Vertigo Analogue Scale (VVAS). Additionally, participants will complete a custom questionnaire developed by the research team and engage in a one-to-one discussion with the investigator to evaluate self-reported changes in VID symptoms and postural stability. This questionnaire will explore aspects such as symptom management, difficulties in daily and community activities, adaptations to life roles following VID, and symptom changes experienced during and after the intervention period. It will also explore the acceptability of the intervention and participants’ willingness to engage in the home-based tasks as part of an ongoing exercise routine. Data collected from this questionnaire will provide valuable insights into user experience.