Abstract
Introduction Homonymous hemianopia is a common and disabling visual problem after stroke. Currently, prism glasses and visual scanning training are proposed to improve it. The aim of this trial is to determine the effectiveness of these interventions compared to standard care.
Methods and analysis The trial will be a multicentre three arm individually randomised controlled trial with independent assessment at 6 week, 12 week and 26 week post-randomisation. Recruitment will occur in hospital, outpatient and primary care settings in UK hospital trusts. A total of 105 patients with homonymous hemianopia and without ocular motility impairment, visual inattention or pre-existent visual field impairment will be randomised to one of three balanced groups. Randomisation lists will be stratified by site and hemianopia level (partial or complete) and created using simple block randomisation by an independent statistician. Allocations will be disclosed to patients by the treating clinician, maintaining blinding for outcome assessment. The primary outcome will be change in visual field assessment from baseline to 26 weeks. Secondary measures will include the Rivermead Mobility Index, Visual Function Questionnaire 25/10, Nottingham Extended Activities of Daily Living, Euro Qual-5D and Short Form-12 questionnaires. Analysis will be by intention to treat.
Introduction
Homonymous hemianopia results in loss of one-half of the visual field in both eyes.1 ,2 The reported prevalence of visual field loss following stroke has been as high as 63%3 in hospital populations although estimates vary widely as the proportion testing positive is highly dependent on time post-stroke. Homonymous hemianopia on admission is linked to poor early survival and, conversely, around 10%3 experience full spontaneous recovery within the first 2 weeks. Visual field defects can seriously impact on functional ability and quality of life following stroke.4 ,5 Patients with visual field defects have an increased risk of falling,6 impaired ability to read, poor mood and institutionalisation.6–9 Visual field loss may impact on a patient’s ability to participate in rehabilitation, and may ultimately result in poor long-term recovery.8 Visual field loss can result in accidents or injuries which have subsequent cost implications to the National Health Service and the patient.10
Service provision is presently inconsistent.11 A recent survey of orthoptists has shown that 45% of stroke services provided no formal vision assessment for patients with stroke.12 A further survey of current practice in stroke care in patient settings in Scotland identified that only 7% of stroke units had a policy relating to vision assessment and management.13 Both surveys illustrate the lack of standardisation of practice in relation to visual impairment assessment and treatment for stroke survivors. The Department of Health National Stroke Strategy,14 argues that vision and visual perceptual difficulties are components requiring multifaceted stroke specific rehabilitation and support. The Royal College of Physicians recently revised their guidance for stroke and currently recommend that every patient who has had a stroke should have a practical assessment of vision and examination of the visual field.15 They also advise that any patient whose visual field defect causes practical problems should be taught compensatory techniques with prism treatment provided only by those with expertise in this treatment. The Scottish Intercollegiate Guideline Network (SIGN) guidelines for management of patient with stroke (SIGN 118)16 ,17 advocates that all patients with stroke should be screened for visual problems and also suggests visual scanning compensatory training techniques as potentially improving function outcomes after stroke. The SIGN 118 guidelines also stress the need for further high-quality research to investigate the effectiveness of interventions for visual field defects.
Two key interventions commonly used in the clinical setting to improve vision in hemianopia are visual scanning compensatory training and provision of prisms.13 We completed a literature search and identified a number of reviews, which have investigated the efficacy of interventions for hemianopia after stroke.8 ,18–22 We extracted data on any intervention studies investigating visual scanning compensatory training or prisms and searched for any subsequent or on-going randomised controlled trials (RCTs).
A number of intervention studies have been conducted for visual scanning compensatory training. There is consistency between these studies in identifying benefits associated with scanning or eye movement training. One RCT has reported on the use of either 15 dioptre plastic press-on fresnel prisms or no prism treatment. The results of this study demonstrated improvements in visual impairment, but not in functional outcomes.23 It was limited by the inclusion of patients with hemianopia and neglect, by the small prism power and by use of screening vision measures. We identified four longitudinal studies of prism use. Bowers et al24 and Giorgi et al25 completed prospective cohort studies, investigating Fresnel prism peripheral segments. The reported outcome for these studies was ‘clinical success’, as measured by continued wear: 74% and 67% of participants, respectively, were reported to continue to wear the prisms at the end of the study, and 47% and 42%, respectively, at long-term follow-up. In a study of 12 patients fitted with 40 dioptre prisms, an effective expansion of the visual field (in the presence of prism wear only) was reported of up to 20°26; however, there was no control group included in this study.
Our aim is to undertake a pilot RCT to provide essential information for the conduct of a subsequent full phase III study to determine the clinical and cost-effectiveness of visual rehabilitation interventions as compared to NHS standard care, in patients with hemianopia following stroke. We wish to determine whether visual rehabilitation is more effective than standard care (advice only) at improving functional outcome in patients with hemianopia following stroke, and whether prism therapy or visual search therapy is more effective at improving functional outcome in patients with hemianopia following stroke.
μέσω BMJ Open | Mobile.
TBI Rehabilitation 