How effective is low vision service provision? A systematic review

Methodological quality of the review: Low confidence

Author: Binns AM, Bunce CV, Dickinson C, Harper RA, Tudor-Edwards R, Woodhouse M, Linck P, Suttie A, Jackson J, Lindsay J, Wolffsohn J, Hughes L, Margrain TH.

Region: Not specified

Sector: Visual impairment

Sub-sector: Low vision; provision of service; visual impairment, quality of life

Equity focus: None specified

Review type: Effectiveness review

Quantitative synthesis method: Narrative analysis

Qualitative synthesis methods: Not applicable

Background

Low vision rehabilitation primarily improves the lives of people with sight loss in that it improves functional ability, as well as possibly more general aspects including quality of life and psycho-social status. Recently, different rehabilitation models have been developed to meet these goals. However, there is a limited evidence base regarding the ability of these different strategies to achieve positive outcomes in various patient groups.

Research objectives

To provide a critical evaluation of current literature regarding the effectiveness of different models of low vision rehabilitation service provision in persons with visual impairment.

Main findings

The study identified 478 potentially relevant studies. Out of these, 52 related to general effectiveness of low vision services, four to children and minority groups and two to health economics evaluations of visual rehabilitation. In all, 52 studies were included which mostly used before and after design, although they lacked a control group and it was difficult to determine the effect of the intervention in many cases. Only seven of the studies were randomized controlled trials and most of these had significant design or reporting flaws.

The review suggests that the provision of low vision services results in an improvement in clinically measured visual function, particularly regarding reading. Low vision services are therefore regarded as an effective means of improving reading ability in patients with visual impairment. Despite this, the effect of low vision rehabilitation services on mood, vision related quality of life and health related quality of life are less clear.

The authors suggest more high quality research to determine which types of rehabilitation services are more effective as well as the cost effectiveness of rehabilitation.

Methodology

The authors included studies that involved people with visual impairment, include a comparison, and be of rehabilitation service. They searched databases such as Web of Science, Embase, Medline, Cochrane Central, PsycINFO, and CRD databases. They used 3 search terms: target population, intervention and study design/outcomes. The search was also supplemented by a manual search of the bibliographies of included studies as well as asking experts in the field for additional sources of information. The review was limited to available English Language studies.

The authors conducted a narrative synthesis of findings rather than a meta-analysis or sensitivity analysis due to the heterogeneity of the included studies, their varying methodology, outcomes, follow-ups and interventions. To aid the qualitative comparison of the outcomes of different studies, the study calculated effect sizes where possible using Cohen’s d method.

Applicability/external validity

The authors did not discuss the applicability/external validity of the results.

Geographic focus

The authors were not clear whether the search was restricted to specific income settings, and did not report the geographical location of studies included in the review.

Quality assessment

There is low confidence in the conclusions about the effects of this study as important limitations were identified. Although the review authors conducted a comprehensive search of the literature, language bias was not avoided. It was not clear whether study selection as well as data extraction of included studies were conducted by two reviewers independently. As such, we cannot be confident that characteristics and results of included studies were reliably reported and selection bias was avoided, which impacts on the reliability/validity of this review’s findings.