Title: Measuring the effects of eye alignment surgery - a feasibility study.
Funder: Health Education England

Abstract: Background Strabismus is an abnormal alignment of one eye, which occurs in 4-5% of adults. Patients with strabismus may have visual problems, such as double vision, but for many their abnormal eye alignment is the main concern. The psychosocial impact' of having strabismus negatively affects patients by reducing self-esteem and self-confidence, affecting interpersonal relationships and reducing their ability to gain employment. Surgery on the eye muscles may be offered as a reconstructive procedure to improve eye alignment and reduce the psychosocial impact of having strabismus. Currently eye alignment surgery is funded by the NHS based on evidence of psychosocial benefits to the patient. However, some commissioners in England have withdrawn funding for this procedure over concerns it offers cosmetic benefit only. More evidence is needed to determine the effects of eye alignment surgery to inform decisions about commissioning and funding of NHS services. Research evidence shows some visual abilities can improve following eye alignment surgery (expanded field of and unexpected binocular vision) and some patients report long term functional benefits in daily activities or tasks, despite surgery for psychosocial benefit. Yet there are gaps in our knowledge and understanding of the effects of eye alignment surgery, as studies are often descriptive or report one aspect of vision only. Robust evidence is required and this study is needed to determine the changes in visual function, daily activities and task performance that can occur. Aims To undertake a mixed methods feasibility study to determine the changes in visual function, daily activities and task performance that can occur following eye alignment surgery for strabismus. Research question What are the effects of eye alignment surgery for psychosocial benefit in strabismus? Plan A mixed methods study aims to generate more insights than would be possible from a qualitative or quantitative study alone. The qualitative phase includes interviews with adult patients who have recently undergone eye alignment surgery for psychosocial benefit. It will identify functional changes they report in their vision, task performance or daily activities following surgery. This patient reported information will improve the design of the quantitative phase, as together with the literature evidence, it will inform the selection of quantitative measures. During the quantitative phase a range of tests to measure different visual functions, task performance and daily activities will be used. Some of these tests will be developed during the clinical training part of the fellowship and supported by the expert advisory group, which has been brought together to help this aspect of the fellowship. Patients who have chosen to undergo eye alignment surgery for psychosocial benefit will be recruited to have these measurements before and after surgery. This will determine if it is feasible to quantify changes in visual function, task performance or daily activities following eye alignment surgery. Potential benefits The results will provide more information to patients, clinicians and commissioners of NHS services about the effects of eye alignment surgery. In particular the changes in visual function, daily activities and task performance that can occur, which will be in addition to the known psychosocial benefits. The results will inform a larger, more complex study by determining the most appropriate tests to best quantify the outcomes from surgery, whilst remaining acceptable to patients. The results will allow a sample size calculation and identify potential issues with the design of, and recruitment and retention to, the larger study. The larger study will compare different groups of strabismus patients to determine if there are particular groups that can achieve more additional benefits from surgery than others and what these benefits mean to patients everyday lives and quality of life.

Lay abstract: Having an eye that turns, so that both eyes aren't lined up in the same direction, is known as strabismus (or squint). This disorder affects 4-5% of the population. Patients with strabismus may have visual problems, such as double vision, but for many it is the misalignment of their eyes that is their main concern. Having misaligned eyes is associated with anxiety and depression, it can reduce a person's self-esteem and self-confidence, causing problems with their relationships with other people and reduces their ability to get a job. For the majority of patients with strabismus the main reason for having surgery is to restore the alignment of their eyes to a straighter position. This is called a psychosocial benefit' and can improve their quality of life. If a patient were to suffer less with anxiety and depression and feel more confident in social situations as a result of eye alignment surgery, this would be an example of psychosocial benefit'. Therefore the NHS currently funds eye alignment surgery because of these known benefits to patients; however NHS services in some regions have withdrawn funding for this surgery over concerns that there is not enough evidence of the benefit to patients. Approximately 8.4million is spent on adult eye alignment surgery per year in England. It is not fully understood whether eye alignment surgery causes additional benefits above and beyond the psychological and social benefits. Evidence from the literature suggests that there are aspects of patients' lives and their vision that can improve following eye alignment surgery. But, the evidence comes from small studies that often only describe one aspect of vision. In order to better understand and measure the effects of eye alignment surgery, this study will firstly determine if it is achievable to measure changes in vision and the ability to perform everyday tasks after eye alignment surgery. The study aims to increase our knowledge and understanding of the potential benefits of alignment surgery, and answer the questions that haven't been addressed in smaller studies. Patients with strabismus and patients who had recently undergone eye alignment surgery were involved with the development of this research proposal in two focus groups. Their involvement has highlighted that information about possible changes in vision and ability to perform daily tasks after surgery is of high importance to patients deciding whether to undergo eye alignment surgery or not. Participants in the patient focus group will be invited to continue their involvement as part of an advisory group to ensure the study remains focused on what is important to patients. In the first part of the study, patients who have had eye alignment surgery will be asked their views on what has changed for them following surgery. This study will uniquely focus on their experiences of changes in vision or other useful aspects of everyday living, such as task performance. The results from the first part will inform the second part of the study. In the second part, patients who have chosen to undergo eye alignment surgery will be recruited to have measurements of their vision and task performance before and after surgery. These results will be compared to a group with strabismus but not having surgery to determine whether it is feasible to measure changes in visual function and task performance after surgery. The results from this study will firstly decide whether it is feasible to measure changes in vision and task performance in patients who have had eye alignment surgery for psychological and/or social reasons. Secondly, the results will determine if the tests of vision and task performance are acceptable for patients, and whether the range of tests can be narrowed down to the best at measuring any benefits. Thirdly, the feasibility of the study design will also be determined, specifically is it practical to recruit patients to a study that measures these outcomes before and after eye alignment surgery? This will provide important additional information for decision makers within local NHS services, patients and clinicians about the benefits that patients can gain from eye alignment surgery. In particular it will answer the initial question can additional functional benefits in vision and everyday task performance be measured?' These results will be used to plan a larger trial comparing different groups of patients with strabismus. This larger trial will measure the additional visual and task performance benefits gained by different groups of strabismus patients following eye alignment surgery, and how these benefits fit with the improvements to their quality of life.

Research activity codes: 6.4 SURGERY
Health categories: EYE