Visual scanning training for hemianopia
Research type
Research Study
Full title
A randomised controlled trial of scanning eye training as a rehabilitation choice for hemianopia after stroke (SEARCH)
IRAS ID
293576
Contact name
Fiona Rowe
Contact email
Sponsor organisation
University of Liverpool
ISRCTN Number
ISRCTN93008420
Duration of Study in the UK
2 years, 0 months, 0 days
Research summary
Research Summary
Sight is considered by many as our most important sense. One part of sight is our field of vision. The normal visual field allows us to look straight ahead at an object but still be visually aware of our surroundings out to the far sides of our vision. After stroke a common problem is ‘hemianopia’ which is loss of one half of the visual field leaving people with a ‘blind’ side to the right or left side of their vision.
Hemianopia occurs suddenly in 30% of stroke survivors with devastating impact on quality of life - individuals cannot drive, have difficulty reading, bump into people and objects, and can lead to a loss of independence, social isolation, falls and depression. It may also affect peoples’ abilities to undertake treatment for other stroke-related problems.
Providing treatment to help stroke patients adapt to their visual field loss is variable and not standardised in the NHS because of uncertainty about what works best and when is the best time to offer treatment. This causes unacceptable inequality in health care.
A review of treatment options for hemianopia concluded that visual search training is potentially useful. Visual search training involves repeated practice by the patient at locating different targets on both the seeing and blind sides of their visual field. This training can be provided by many methods – some needing paper cards for the training and others needing computers. Paper-based visual search training is available to ALL patients whereas computer training is not.
Our VISION ‘pilot’ trial tested how useful a new portable paper-based training was in comparison to prism treatment and no treatment. It provided information on how many patients would take part in a trial, what assessments were important and what people thought of the treatments. We have used the published VISION results to design this new trial.
In this (SEARCH) trial, we aim to find out how effective the paper-based visual search training is for hemianopia after stroke. In a randomised clinical trial 71 people will undertake eye search training for 30 minutes daily, 7 days/week over 6 weeks; 71 people will undertake sham training for 30 minutes, 7 days/week over 6 weeks.. Everyone will be followed for 6 months. We will test peoples’ visual reactions and independence in daily activities and compare groups to see if there is more benefit from search treatment.
This trial is important as it addresses an area of treatment for which there is limited evidence and currently no standard care in the NHS. This treatment is a top priority highlighted by 2 national surveys that involved a large number of patients and carers. Despite research results indicating that search and detection of objects in the ‘blind’ side can be improved with training, questions remain about patient benefit from this treatment and cost of treatment. There is limited information on how this type of treatment affects daily life.Summary of Results
General information This trial was carried out by the University of Liverpool by the VISION research unit, led by Prof Fiona Rowe. The trial was sponsored by the University of Liverpool and funded by Fight for Sight and the Stroke Association.
The trial was supported by a trial management group to oversee the day-to-day management, by a trial steering group and independent data and safety monitoring group who ensured the trial followed due process, and by a consumer advisory group who provided all patient and public involvement.
The trial opened to recruitment in April 2021 with the first participant being recruited in May 2021. Recruitment completed in September 2023 with final follow-up in March 2024. Thirty-four hospitals across England, Wales and Scotland recruited participants to the trial.Background
Sight is frequently regarded as our most important sense. One key aspect of sight is our field of vision. The problem we addressed is 'homonymous hemianopia' - loss of the field of vision in both eyes to the right or left side. This occurs suddenly. The person can no longer 'see' half of their visual world with devastating impact to quality of life.
Hemianopia is reported in about 30% of stroke survivors. Few have full recovery - most are left with complete or partial visual field loss. Hemianopia can have devastating consequences for those affected. Stroke patients with hemianopia show substantial reductions in both health and vision-related quality of life. Extensive visual field loss causes greater restrictions in daily life. Individuals cannot drive, have reading difficulties, have reduced mobility and increased collisions with objects and people leading them to become fearful and isolated.
Treatment for hemianopia is not standardised with variable/no treatment provided in the NHS. One treatment showing potential benefit for stroke survivors with hemianopia is visual scanning training. There is some limited evidence that compensatory visual scanning training is effective at improving scanning outcomes. Improving visual scanning is essential to improving speed and accuracy of detection of objects to the affected, blind side and leading to improved adaptation to hemianopia. Adaptation is key to acquiring better visual function and, in turn, could lead to improvements in other domains such as increased confidence in mobility/navigation and consequent increased independence.Aim
We aimed to evaluate clinical effectiveness of visual scanning training vs sham training, for homonymous hemianopia.Who participated in the study?
We recruited adult stroke survivors with confirmed stable homonymous hemianopia. All had clinically diagnosed stroke, were aged 18+ years, had stable hemianopia, were >4 weeks and <26 weeks post stroke onset, were able to engage in training, and provided informed or proxy consent.
Overall, 161 participants were randomised; 80 in the visual scanning training (VST) group and 81 in the sham training group. Three participants withdrew consent to use data so were not included in any analysis. Of 158 participants, 78 were in the VST group and 80 in the sham training group.What treatments or interventions did the participants take/receive?
Arm A: Visual scanning training.
The SEARCH trial used the VISION intervention - a paper-based VST package, consisting of training sheet and training instructions. It is portable, self-administered, does not need expert set-up, does not require expertise to use it or support its use, and can be used at home or any care setting. The sheet consists of A4-size landscape paper with targets filling the paper. The patient held the sheet at a distance of 8 inches/20cms from their eyes to achieve a 30-degree area of field of vision to the right and left sides. Following the instruction sheet, the patient performed a series of tasks, in which they transferred/jumped gaze quickly between targets. Tasks included detection of and discrimination between different targets. This engaged saccadic (fast) eye movements required for scanning and search processes. Coloured targets could be changed to patterned targets if the patient had a colour vision deficiency. The training period could run beyond 6 weeks if the participant did not gain the minimum treatment dose (20 hours) over 6 weeks.
Arm B - Sham training
The control was sham training comprising a series of slow, tracking eye movements undertaken with both eyes open (versions) and with each eye covered in turn (ductions). These movement patterns did not engage scanning eye movements. A training sheet and instructions were provided, similar to the intervention arm.What medical problems (adverse reactions) did the participants have?
There were 29 (20 participants) related adverse events in this trial and spread across both groups. Twenty-five were mild, two moderate and two severe, and largely related to eye strain, headache and blurred vision. There were five non-related serious adverse events which related to new strokes, high blood pressure and a fall with urinary tract infection.What happened during the study?
All participants began their training allocation. During the first 6 weeks of training, over 70% of participants undertook training every day or most days in the VST and sham training groups respectively. After the required 6-week treatment period, participants could continue if the dose had not been achieved, or participants could continue voluntarily and thus, increase the dose. After 12 weeks, they could also continue voluntarily.What were the results of the study?
All participants began their training allocation. Both groups were comparable in terms of baseline characteristics such as age, sex, stroke severity, stroke type, extent of hemianopia and side of hemianopia.
Primary analysis was carried out on 104 participants with quality of life data (measured using the VFQ-25 questionnaire) at both baseline and 26 weeks. Further analysis was undertaken for 120 participants using additional visit information. We found no significant differences between groups for primary and secondary outcome measure comparisons from baseline to 26 weeks. Both groups improved in all primary and secondary outcomes. There were no differences between the groups for any outcome measure. However, it was possible that there was a placebo effect from additional information resources and clinician input during the first 6 weeks of treatment and for the sham training providing a treatment effect. These aspects warrant further research.REC name
Wales REC 1
REC reference
21/WA/0030
Date of REC Opinion
11 Mar 2021
REC opinion
Further Information Favourable Opinion