A Randomised Controlled Trial of Treatment for Post-Stroke hom*onymous Hemianopia: Screening and Recruitment (2024)

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Neuroophthalmology
v.40(1); 2016 Feb
PMC5123152

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Neuroophthalmology. 2016 Feb; 40(1): 1–7.

Published online 2016 Jan 19. doi:10.3109/01658107.2015.1126288

PMCID: PMC5123152

PMID: 27928375

Fiona J. Rowe,^a Elizabeth J. Conroy,^b P. Graham Barton,^c Emma Bedson,^d Emma Cwiklinski,^d Caroline Dodridge,^e Avril Drummond,^f Marta Garcia-Finana,^b Claire Howard,^g Stevie Johnson,^h Claire MacIntosh,^e Carmel P. Noonan,ⁱ Alex Pollock,^j Janet Rockliffe,^k Catherine M. Sackley,^l and Tracey Shipman^m

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ABSTRACT

The authors report the screening process and recruitment figures for the VISION (Visual Impairment in Stroke; Intervention Or Not) trial. This is a prospective, randomised, single-blinded, three-arm controlled trial in 14 UK acute hospital stroke units. Stroke teams identified stroke survivors suspected as having hom*onymous hemianopia. Interventions included Fresnel prisms versus visual search training versus standard care (information only). Primary outcome was change in visual field assessment from baseline to 26 weeks. Secondary measures included change in quality-of-life questionnaires. Recruitment opened in May 2011. A total of 1171 patients were screened by the local principal investigators. Of 1171 patients, 178 (15.2%) were eligible for recruitment: 87 patients (7.4%) provided consent and were recruited; 91 patients (7.8%) did not provide consent, and 993 of 1171 patients (84.8%) failed to meet the eligibility criteria. Almost half were excluded due to complete/partial recovery of hemianopia (43.6%; n = 511). The most common ineligibility reason was recovery of hemianopia. When designing future trials in this area, changes in eligibility criteria/outcome selection to allow more patients to be recruited should be considered, e.g., less stringent levels of visual acuity/refractive error. Alternative outcomes measurable in the home environment, rather than requiring hospital attendance for follow-up, could facilitate increased recruitment.

KEYWORDS: Fresnel prisms, hom*onymous hemianopia, randomised controlled trial, recruitment, screening, stroke, visual search

Introduction

hom*onymous hemianopia is loss of half of the field of vision to the right or left side. It may be complete, in which total field loss occurs to one side from the vertical midline outwards, or may be partial, in which part of the field remains either centrally or in the periphery (temporal, superior, or inferior remnant).1

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Figure 1.

Methods

The VISION trial was conducted as a multi-centre three-arm pilot randomised controlled trial with independent assessment of results across 14 hospitals. For the full trial protocol, see Rowe et al.17 Interventions were Fresnel prisms (arm a), visual search training (arm b), and standard care (information sheets only) (arm c).

Setting

The trial was undertaken in hospital in- and outpatient and primary care rehabilitation settings.

Target population

Patients were identified in the acute phase following admission to hospital with a stroke (at 2 weeks post stroke onset).

Inclusion criteria

Participants were 18 years of age and older, and had best-corrected visual acuity of ≥6/18 in either eye, hom*onymous hemianopia, and refractive error within ±5 D. Measurements of vision were by orthoptic assessment.

Exclusion criteria

Participants were excluded if they were unable to consent due to severe cognitive impairment; unwilling to participate in the study; had ocular motility impairment and visual inattention in addition to the visual field impairment (as assessed by the orthoptist); and had pre-existent visual field impairment.

Screening

The stroke team within participating stroke units identified stroke survivors suspected of having a hom*onymous hemianopia. The stroke research nurse listed details of these patients on the trial screening log. The principal investigator (PI) for the trial was an orthoptist specialising in the assessment of stroke-related visual impairment who arranged assessment of these patients.

Recruitment

Patients listed on the trial screening log were contacted either in person if an inpatient, or via telephone if discharged. Patients were invited for eye assessment, conducted by the PI in the eye clinic. At assessment, patients who did not meet the inclusion criteria were excluded and reasons for exclusion were recorded. All patients meeting the inclusion criteria were invited to participate in the trial. Patients who declined to participate were invited to provide a reason, although PIs made it clear that this was not required; any reasons provided were recorded.

Results

Recruitment period

The VISION trial opened to recruitment in May 2011. During the recruitment period, 15 NHS (National Health Service) Trusts were opened to recruitment; five of these opened in the first months. Recruitment was slow and the number of recruiting sites was subsequently increased. The month and year when each site opened to recruitment is given in Table 1. Time taken to obtain Research and Development unit approvals locally combined with completion of trial setup paperwork by local research teams ranged from 1 to 21 months. One site opened in the final month of recruitment period and therefore did not contribute to screening and so is not listed in the results tables.

Table 1.

Summary of site screening and recruitment.

Site	Date site opened to recruitment	Months open to recruitment*	Number of screened patients	Number of ineligible patients	Number of unwilling patients	Number of eligible patients	Total number of patients recruited	Consent
1	May 2011	28	122	110	5	12	7	58%
2	May 2011	28	104	92	3	12	9	75%
3	May 2011	28	187	158	15	29	14	48%
4	May 2011	28	112	85	13	27	14	52%
5	August 2011	25	238	224	11	14	3	21%
6	March 2012	18	72	64	5	8	3	38%
7	March 2012	18	38	33	3	5	2	40%
8	April 2012	17	36	18	11	18	7	39%
9	April 2012	17	89	77	9	12	3	25%
10	May 2012	16	53	42	5	11	6	55%
11	June 2012	15	25	13	7	12	5	42%
12	November 2012	10	31	23	2	8	6	75%
13	January 2013	8	22	18	2	4	2	50%
14	February 2013	7	42	36	0	6	6	100%
15	July 2013	2	NA	NA	NA	NA	NA	.

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*Rounded up to nearest month.

Screening data

Total screening and recruitment numbers across 14 sites are provided in Table 1. A total of 1171 patients were identified by the stroke team as having suspected hom*onymous hemianopia and were recorded on the trial screening log. Figure 1 shows the flow of eligibility.

Table 2.

Reasons for being ineligible for recruitment and not providing consent.

Reason: Ineligible	Total screenings	Proportion	Reason: Consent not provided	Total number	Proportion
Unstable hemianopia	511	43.6%	Did not wish to provide reason	52	57.1%
Ocular motility impairment and/or visual inattention	161	13.7%	Did not want to attend follow-up visits	25	27.5%
Not able to consent/understand	117	10.0%	Did not want to be randomly assigned treatment	8	8.8%
Visual acuity worse than 0.5 logMAR	97	8.3%	Did not want to be assigned to information only group	1	1.1%
Pre-existent visual field impairment	46	3.9%	Other reason: Terminal patient	1	1.1%
Died	33	2.8%	Other reason: Patient wishes to see if recovers before participating	1	1.1%
Moved/lived out of area	17	1.5%	Other reason: Family did not want to participate	1	1.1%
Could not attend	22	1.9%	Other reason: Patient wishes to have more time to decide	1	1.1%
Did not attend	11	0.9%	Other reason: Patient does not see benefit in trial	1	1.1%
Unable to contact patient	11	0.9%	Other reason: Patient does not want to travel to appointments	1	1.1%
Further stroke	8	0.7%	Total patients	91	100%
High refractive error	7	0.6%
Unable to read and understand English	3	0.3%
Further TIA (transient ischaemic attack)	2	0.2%
Does not have transport	2	0.2%
Not 18 years of age or older	2	0.2%
Other:	5	0.5%
No reason provided	2	0.2%
Total patients	993	84.8%

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Note. Other = Patient denied vision problem, Barrier nurse, Unable to be assessed by orthoptist, Patient having further treatment for migraine.

Recruitment data

In total 178 patients (178/1171, 15.2%) were eligible for recruitment, and 87 of these (87/178, 48.9%) provided consent and were subsequently recruited to the trial. Reasons eligible patients declined consent are outlined in Table 2. Ninety-one patients did not provide consent (91/178, 51.1%), of which 52 (52/91, 57.1%) did not disclose a reason. Of the patients who did provide a reason, 25 patients (25/91, 27.5%) did not want to attend the follow-up appointments required for the trial and 8 (8/91, 8.8%) did not want to be randomly assigned.

The overall proportion of screenings resulting in recruitment was 7.4% (87/1171). This proportion varied across the 14 sites from 1.26% (3/238) to 20% (5/25), with Table 1 providing more details. Time open to recruitment varied across sites, with a median of 17.5 months and range of 7 to 28 months (Table 1), with lower recruitment rates in sites open longest.

Discussion

The recruitment phase of the VISION trial commenced in May 2011 and ceased in August 2013. During this period, 1171 patients were screened of which less than 10% were randomised (n = 87). Recruitment was initially slow, and formal feedback from the PIs during an end-of-trial investigator meeting suggests that this may be due partly to lack of familiarity with the trial and research process.

Research is relatively new in this field. Staff, who are new to research trials, must learn new processes (as was the case in our trial). For this trial, a local orthoptist was the principal investigator at each recruitment site. Many of our PIs had participated in previous observation studies, but this was their first PI role in a trial.

There was also a learning curve for the stroke research nurses. Although experienced at recruiting, for many they had to acquire knowledge of the various visual conditions that could coexist with hom*onymous hemianopia to aid identification of suspected hemianopia. Continuous feedback and information were provided by the orthoptists to the stroke teams to facilitate an on-going update of knowledge of visual conditions, particularly for new staff with no prior vision experience. It was recognised that lack of knowledge and information could be a limitation in the identification of hemianopia by members of the stroke team. Sites opening to recruitment a year or longer after the initial sites possibly benefited from the knowledge and experience passed on by the orthoptist PIs of the original sites. Consequently, recruitment rate was generally higher for the later opening sites. These may be important lessons for future studies in this area.

Low recruitment numbers remained an issue through the first year of recruitment; there were fewer eligible patients than expected and smaller numbers of patients agreeing to take part. Slow and low numbers of recruitment to trials are well reported.18^–21 Barriers to trial participation include a lack of patient time, issues with their perceived importance of the trial, poor patient-clinician relationship, and a lack of compatibility between the trial protocol and usual clinical practice.19 Strategies to improve recruitment to trials have been advocated and include telephone reminders, participant opt-out versus opt-in options for trial contact, and open designs.21

We found a high number of patients who did not meet the trial inclusion criteria due to full or partial recovery of hemianopia, but other reasons included death prior to baseline assessment, further stroke, patients moved out of area, or could/did not attend baseline assessment appointments. Patients who were eligible but who did not wish to consent to the trial often did not want to attend follow-up appointments, did not want to be randomly assigned to a treatment group or be assigned to the control (no treatment) group, wanted to wait for natural recovery, did not wish to travel to the hospital for appointments (a requirement for outcome measures), did not anticipate any benefit to participating in the trial, or their family did not wish them to participate.

Almost half (511/1171, 43.6%) of all screenings resulted in patients not being recruited for reasons related to recovery of hemianopia, which included either full recovery with return to normal visual field to the previously affected side, or partial recovery to less than one quadrant. The literature reports that up to 44% of individuals have full recovery of visual field and up to 72% have partial recovery, although the extent of this recovery is not stated.2,^6–12 Our screening results show 43.6% full or partial recovery, but of note, the partial recovery in our excluded cases was to less than a quadrant of visual field. This is a positive finding, as a small visual field defect, particularly in the peripheral visual field, may not functionally impede an individual to anything near the extent of impact from complete hom*onymous hemianopia. This factor should be taken into consideration when planning future trials.

Of total screenings, 161 patients were excluded (161/1171, 13.7%) who had acquired eye movement deficits that prevented accurate horizontal gaze to the side of the hemianopia, for example horizontal gaze palsy. The reason for this is that treatment with visual search strategies utilised eye scanning exercises. These rely on the patient being able to make eye movements to look at different targets to the right and left sides of the exercise card. It was important to exclude eye movement deficits that might impede the process of doing the eye scanning exercises. Thus, we propose this inclusion criterion should remain in future trials using visual search training.

Presence of high refractive error precluded the recruitment of only seven patients (7/1171, 0.6%). Formal quantitative perimetry of the peripheral visual field is typically done without glasses, as the frames can impede the test by blocking the stimuli. Individuals with high refractive errors may therefore not detect stimuli if undertaking the test without their glasses. Thus, they were excluded. The level of visual acuity was set at 0.5 logMAR or better level, as quantitative perimetry requires sufficient visual acuity to maintain adequate fixation of the central stable target during formal assessment. Ninety-seven patients (97/1171, 8.3%) did not meet this criterion. It is possible to increase the visual acuity cut-off to a lower acuity level but not less than 6/60 Snellen or 1.0 logMAR level and future trials could consider this. This change in the inclusion criteria would allow a small increase in recruitment of patients, but it would still be necessary to exclude those with visual acuity worse than 6/60 or 1.0 if formal perimetry remained an outcome measure.

A further consideration in relation to formal visual field assessment is that a number of patients could not participate because they did not wish to attend follow-up appointments or had transport difficulties so could not travel for appointments (35 patients, 3%). We required hospital attendance for follow-up appointments because formal visual field assessment was an outcome measurement. A consideration for future hemianopia trials is whether formal visual field perimetry is required as an outcome measure. If outcome measurements could be completed at home or community settings, recruitment may be improved. Furthermore, exclusion based on refractive error or level of visual acuity may not be necessary.

Conclusions

Of 1171 patients screened with possible hemianopia, we identified 178 eligible patients (15.2%) from whom we recruited 87 patients, which represents 7.4% of the total screened patients and 48.9% of eligible patients. Just under half of patients screened could not be recruited because their hemianopia had fully or partially recovered, which is a positive finding for stroke outcomes. It would be possible to recruit a small additional number of hemianopia patients with less stringent inclusion criteria for level of visual acuity and refractive error, and with varied outcome measurements not requiring formal hospital visits for perimetry or other quantitative assessments. Support for staff when screening and recruiting to trials may promote improved recruitment rates across multi-centre trials. Consequently, although we recruited fewer participants than we anticipated, our findings are important for the future planning of trials and studies for the care and treatment of patients with hom*onymous hemianopia.

Acknowledgements

Trial Registration: Current Controlled Trials ISRCTN05956042.

Data sharing statement: There are no additional unpublished data in relation to the screening process for this trial. All data are held at the Clinical Trials Research Unit, University of Liverpool.

We should like to thank the patients and staff who participated in this trial and the following collaborators and investigators: Isabel Ash, Conrad Beacham, Rachel Breen, Judith Burn, Carol Buckley, Joanne Gardiner, Henrietta Holmes-Smith, Sandra Knowles, Tallat Maan, Sonia MacDiarmid, Lorraine North, Leonie Ripley, Claire Scott, Sarah Spencer, Andrew Twigg, Carole-Anne Vince, Data Monitoring Committee (Cicely Freeman, Irene Stratton, David Wright), and Trial Steering Committee (Darren Brand, Catie Bunce, Anne-Marie Mackay, Sarah Peel).

Funding

This trial was funded by the UK Stroke Association, which includes salaries for E.C. The sponsor (University of Liverpool Research Support Office) and funder (the Stroke Organisation) had no role in the study design, collection, management, analysis, interpretation of data, writing of the report, and the decision to submit the protocol for publication.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Funding Statement

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