Low Vision Outcomes Literature Review - RNIB

Low vision service outcomes: a systematic review September 2009
This review has been prepared for the RNIB as part of the Low Vision
Service Model Evaluation (LOVSME) project.
Authors:
Alison Binns, Cardiff University
Catey Bunce, Moorfields Eye Hospital
Chris Dickinson, University of Manchester
Robert Harper, Manchester Royal Eye Hospital
Rhiannon Tudor-Edwards, Bangor University
Maggie Woodhouse, Cardiff University
Pat Linck, Bangor University
Alan Suttie, Fife Society for the Blind.
Jonathan Jackson, Royal Victorial Hospital
Jennifer Lindsay, Royal Victoria Hospital
James Wolffsohn, Aston University
Lindsey Hughes, British and Irish Orthoptic Society
Tom Margrain, Cardiff University Advisory Panel:
Mary Bairstow, Vision 2020 UK
Andy Fisher, Focal Point UK
Lisa Hughes, Service User
Marek Karas, Optometric Advisor
Robert W Massof, Hopkins University School of Medicine.
Anita Morrison-Fokken, FOCUS Birmingham
Joan A Stelmack, Edward E. Hines Jr VA Hospital, Illinois.
Gaynor Tromans. FOCUS Birmingham
Contents
1 Executive Summary 6
1.1 Quality of Evidence 7 1.2 Does rehabilitation improve outcomes for service users? 7 1.3 Is there evidence that some services are better than others? 8 1.4 Do rehabilitation outcomes deteriorate with time? 9 1.5 Is more rehabilitation better? 9 1.6 Studies on children, those of working age and minority groups 9 1.7 How cost-effective is low vision service provision? 9 2 Introduction 12
2.1 Visual Impairment: the scale of the problem 12 2.2 Causes of visual impairment in older adults 15 2.3 Visual loss in children 16 2.4 The Consequences of Visual Impairment 16 2.5 The psychosocial impact of visual loss 17 2.6 The economic impact of visual impairment and associated disabilities
19 2.7 Vision Rehabilitation Services 20 2.8 Outcome Measures for Assessing the Effectiveness of a Service 26
2.8.1 Traditional Outcome Measures 26
2.8.2 Quality-of-life and Functional Self-Assessment Tools 27
2.8.3 Economic outcomes 29 2.9 Implementation of Outcome Measures 30
2.9.1 Mode of Implementation 30
2.9.2 Timing of Outcome Assessment 31 3 Objectives 34
3.1 Primary objective: 34 3.2 Secondary objectives: 34 4 Methods 34
4.1 Outcomes Assessed 34 4.2 Inclusion/Exclusion Criteria 35 4.3 Literature Searching Methods 37 4.4 Evaluating Quality of Evidence 38 4.5 Data extraction 39 4.6 Statistical methods 39 5 Results 41
5.1 Search Results 41 5.2 Quality of included studies 41 5.3 Evidence Synthesis 45 5.4 Effect of Low Vision Service Intervention on Clinical Measures of
Visual Function 45 5.5 Frequency of Use of LVAs Following Low Vision Service Intervention and
Satisfaction with LVAs and Service 48 5.6 Effect of Low Vision Service Intervention on Performance of Activities
of Daily Living (ADLs) 49 5.7 Effect of Low Vision Service Intervention on Vision-Related Quality-of-
Life 54 5.8 Effect of Low Vision Service Intervention on Mood 58 5.9 Effect of Low Vision Service Intervention on Generic Health-Related
Quality-of-Life 62 5.10 The Differential Effect of Low Vision Service Models on
Rehabilitation Outcomes 63 5.11 The Effect of Follow-up Timing on Rehabilitation Outcomes 68 5.12 The Effect of Low Vision Service "Dose" on Rehabilitation
Outcomes 71 5.13 The Effect of Low Vision Services on Rehabilitation Outcomes in
Specific Patient Groups 74 5.14 The Cost-Effectiveness of Low Vision Service Provision 75 6 Summary 77
7 Appendix 1: Key Words used in Identifying Relevant Studies 80
8 Appendix 2: Evidence Synthesis 81
8.1 Table 1a: Characteristics of Included Studies: General 81 8.2 Table 1b: Characteristics of Included Studies: Economic 115 8.3 Table 2a: Characteristics of Excluded Studies: General 119 8.4 Table 2b: Characteristics of Excluded Studies: Economic 125 8.5 Table 2c: Characteristics of Excluded Studies: Specific Patient Groups
e.g. Children 126 8.6 Table 3: Outcome Measures Employed by Studies 128 9 Appendix 3: Risk of Bias Table 157
9.1 Table 1: Risk of bias in included studies 157 9.2 Table 2: Quality Assessment in Economic Studies 189 10 References 192
Executive Summary
Visual impairment is a global concern, which is likely to become more
significant, on a social, economic and personal level, as the standard of
medical care improves, and the average lifespan increases. Low vision
rehabilitation aims to improve functional ability, and possibly wider
aspects, such as quality of life and psychosocial status, in those with
visual impairment. Different service models have been developed to meet
these goals, and there is need for a strong evidence base regarding the
ability of these different strategies to achieve positive outcomes in
various patient groups. This report is a systematic review of the
literature on the effectiveness of different models of vision
rehabilitation.
The primary objective of the review was to assess the effects of low vision
service provision on rehabilitation outcomes in people with a visual
impairment.
Secondary objectives:
1) To assess the relative effects of different service models on
rehabilitation outcomes in people with a visual impairment.
2) To assess the impact of timing of outcome assessment on rehabilitation
outcomes in people with a visual impairment.
3) To assess the evidence for a dose effect on rehabilitation outcomes in
people with a visual impairment.
4) To assess the effect of low vision service provision on special groups
of service users, e.g. people with learning disabilities, children and
people of working age.
5) To assess the costs associated with low vision service provision.
Literature was identified by searching the following databases: Web of
Science, EMBASE, Medline, Cochrane CENTRAL, PsychINFO, and CRD databases.
Additional literature was identified via hand searching of relevant reviews
[82, 115, 131-134], and by asking experts in the field for additional
sources of information.
Of 7,800 potential articles identified by the literature searching
strategies, forty-six of the studies were found to be relevant to the
general effectiveness of low vision services, 4 were relevant to children
and minority groups, and 2 were relevant to the cost-effectiveness of low
vision services.
The findings of the report were as follows:
Quality of Evidence
Whilst there have been many publications on low vision rehabilitation
outcomes the quality of these reports has not always been good. That is,
many studies fail to report in sufficient detail the study design, the
nature of the intervention or indeed their findings (e.g. "p values" are
reported but no data is presented). In addition, few studies control for
any underlying deterioration in visual function during the follow-up
period, which may have masked benefits associated with the rehabilitation.
There is only 1 waiting list controlled randomised controlled trial of low
vision service outcomes. There are 2 randomised low vision service
comparison trials [75, 86-88] and 1 low quality randomised rehabilitation
training comparison trial [142]. Because of the absence of high quality
evidence (RCT) this review also included other types of study (e.g. 'before
and after comparisons') but we excluded those having the weakest study
design (i.e. 'case reports' and 'case series').
In this review we use the terms: 'very good evidence' when referring to the
results of well designed randomised controlled trials; 'good evidence' when
referring to consistent results from at least two robust studies that are
not randomised controlled trials and 'evidence' when referring to the
results from at least one robust study.
Does rehabilitation improve outcomes for service users?
The results reported by studies are dependent on: 1) the nature of the
rehabilitation programme (content and dose), 2) the outcome measures used
(larger effects are observed with functional ability measures, smaller
effects with QOL measures), 3) the characteristics of the people studied,
4) when outcomes are measured, 5) study methodology.
There is good evidence that low vision rehabilitation has a large effect on
clinical reading ability (size of print read and reading speed) e.g. [70,
94, 96, 97, 145].
There is good evidence that low vision aids provided by rehabilitation
services are valued by service users and used at home e.g.[75, 79]
There is very good evidence that Veterans' Affairs rehabilitation
programmes (both inpatient and outpatient) have a very large positive
effect on self reported functional ability e.g. [61, 121, 130].
There is evidence that other rehabilitation programmes have a medium effect
on functional ability e.g. [122].
There is contradictory evidence about the ability of rehabilitation
programmes to improve "vision related quality-of-life". For example, whilst
Kuyk et al (2008) and Stelmack et al., 2002 showed medium/small effects
from the inpatient Veterans' Affairs rehabilitation programme [90] and
Scott et al, (1999) showed a medium effect for a more modest programme (60-
90 min) [147], Lamoureux et al, (2007) showed only a small effect [58] and
DeBoer et al, (2006) and Reeves et al, (2004) no change (before - after)
[75, 83].
There is no evidence that even the comprehensive Veterans' Affairs
rehabilitation programme can improve generic health related quality-of-life
(e.g. SF-36) [61]. Similarly, less intense, multidisciplinary
rehabilitation programmes and hospital based programmes have been unable to
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