Reading aids for adults with low vision

Gianni Virgili; Ruthy Acosta; Lori L Grover; Sharon A Bentley; Giovanni Giacomelli

doi:10.1002/14651858.CD003303.pub3

. Author manuscript; available in PMC: 2015 Jan 10.

Published in final edited form as: Cochrane Database Syst Rev. 2013 Oct 23;10:CD003303. doi: 10.1002/14651858.CD003303.pub3

Reading aids for adults with low vision

Gianni Virgili ¹, Ruthy Acosta ², Lori L Grover ³, Sharon A Bentley ⁴, Giovanni Giacomelli ¹

PMCID: PMC4288929 NIHMSID: NIHMS644936 PMID: 24154864

Abstract

Background

The purpose of low-vision rehabilitation is to allow people to resume or to continue to perform daily living tasks, with reading being one of the most important. This is achieved by providing appropriate optical devices and special training in the use of residual-vision and low-vision aids, which range from simple optical magnifiers to high-magnification video magnifiers.

Objectives

To assess the effects of reading aids for adults with low vision.

Search methods

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 1), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE, (January 1950 to January 2013), EMBASE (January 1980 to January 2013), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to January 2013), OpenGrey (System for Information on Grey Literature in Europe) (www.opengrey.eu/), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov/) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 31 January 2013. We searched the reference lists of relevant articles and used the Science Citation Index to find articles that cited the included studies and contacted investigators and manufacturers of low-vision aids. We handsearched the British Journal of Visual Impairment from 1983 to 1999 and the Journal of Visual Impairment and Blindness from 1976 to 1991.

Selection criteria

This review includes randomised and quasi-randomised trials in which any device or aid used for reading had been compared to another device or aid in people aged 16 or over with low vision as defined by the study investigators.

Data collection and analysis

At least two authors independently assessed trial quality and extracted data.

Main results

We included nine small studies with a cross-over-like design (181 people overall) and one study with three parallel arms (243 participants) in the review. All studies reported the primary outcome, results for reading speed.

Two studies including 92 participants found moderate- or low-quality evidence suggesting that reading speed is higher with stand-mounted electronic devices or electronic devices with the camera mounted in a ‘mouse’ than with optical magnifiers, which in these trials were generally stand-mounted or, less frequently, hand-held magnifiers or microscopic lenses. In another study of 20 participants there was moderate-quality evidence that optical devices are better than head-mounted electronic devices (four types).

There was low-quality evidence from three studies (93 participants) that reading using head-mounted electronic devices is slower than with stand-based electronic devices. The technology of electronic devices may have changed and improved since these studies were conducted.

One study suggested no difference between a diffractive spectacle-mounted magnifier and either refractive (15 participants) or aplanatic (15 participants) magnifiers.

One study of 10 people suggested that several overlay coloured filters were no better and possibly worse than a clear filter.

A parallel-arm study including 243 participants with age-related macular degeneration found that custom or standard prism spectacles were no different from conventional reading spectacles, although the data did not allow precise estimates of performance to be made.

Authors' conclusions

There is insufficient evidence on the effect of different types of low-vision aids on reading performance. It would be necessary to investigate which patient characteristics predict performance with different devices, including costly electronic devices. Better-quality research should also focus on assessing sustained long-term use of each device. Authors of studies testing several devices on the same person should consider design and reporting issues related to their sequential presentation and to the cross-over-like study design.

Medical Subject Headings (MeSH): *Reading, *Sensory Aids, Eyeglasses, Lenses, Macular Degeneration [complications], Optical Devices [*standards], Randomized Controlled Trials as Topic, Vision, Low [*rehabilitation], Visual Acuity, Visually Impaired Persons [*rehabilitation]

MeSH check words: Adult, Humans

Background

Description of the condition

There is no single globally-accepted definition of low vision (also known as partial sight, visual impairment and subnormal vision). However, there is general consensus that low vision is an uncorrectable loss of vision that interferes with daily activities. Definitions normally incorporate an estimate of visual loss in terms of impairment (e.g. measuring visual acuity or visual fields), or in terms of disability (measuring the ability to perform a certain task). One such definition states that low vision is the inability to read a newspaper at a normal reading distance (40 cm) with best refractive correction (Legge 1991).

The World Health Organization (WHO) has established criteria for low vision which are used in the International Classification of Diseases (WHO 2010). Low vision is defined as a best-corrected visual acuity worse than 0.5 logMAR (Snellen 6/18 or 20/60) but equal to or better than 1.3 logMAR (3/60 or 20/400) in the better eye, or visual field loss corresponding to less than 20 degrees in the better eye with best possible correction. Blindness is defined as a best-corrected visual acuity worse than 1.3 logMAR or a visual field no greater than10 degrees around central fixation in the better eye with best possible correction. Visual impairment includes low vision as well as blindness. In the United States, legal blindness is defined as a visual acuity of 1.0 logMAR (6/60 or 20/200) or worse in the better eye.

Blindness is one of the most common disabilities (Congdon 2003): an estimated 39 million people were blind a decade ago, i.e. at the time of the last accurate assessment (Pascolini 2011). Among people older than 40 years in the USA, 937,000 were blind in 2002. Figures for the developing world, where 90% of world blindness exists, and for the developed world are expected to increase significantly during the next decades as the world's population ages. Causes of blindness are associated with race and ethnicity in the USA (Congdon 2004): age-related macular degeneration (AMD) is the most common cause in white people, whereas cataract, glaucoma and diabetic retinopathy are the leading causes in Hispanic and black people. Different treatable or preventable conditions are the most frequent causes of blindness in developing countries: infectious disease, nutritional causes, and especially cataract and refractive error (Congdon 2003; Pascolini 2011).

In industrialised countries, low vision is found principally in the 75+ age group (Margrain 1999; Tielsch 1990) and has been ranked third behind arthritis and heart disease among conditions that cause people older than 70 years to need assistance in activities of daily living (Scott 1999). The aging population, combined with the dramatic increase in visual impairment in the older age groups, explains the significant increase seen in the demand for low-vision services.

Description of the intervention

The purpose of low-vision rehabilitation is to allow the person to resume or to continue to perform daily living tasks. This is achieved by providing appropriate optical devices, environmental modifications and special training in the use of residual vision and use of low-vision aids (Massof 1998). Without rehabilitation people with decreased visual acuity often abandon reading and other tasks requiring detailed vision. For individuals with extensive loss of visual field, orientation and mobility can become difficult. For a person with low vision, reading has been identified as one of the most important tasks or goals to achieve (Leat 1994; Shuttleworth 1995). People using low-vision aids have reported improvements in reading a specific letter size both during distance and near work and have found optical aids useful to perform tasks (Humphry 1986; Nilsson 1990; Virtanen 1991). A low-vision aid (LVA) is any device that enables a person with low vision to improve visual performance.

Common optical low-vision devices or aids include:

magnifiers - these sometimes have their own illumination and are either battery-powered or rechargeable from mains electricity. They may be hand-held or mounted on a stand or on spectacles;
telescopes - for work where the reading matter is distant, a telescope can be mounted on a spectacle frame. This gives a longer working distance, although less can be seen at one time because the field is necessarily restricted. Telescopes may also be hand-held.

Electronic aids include primarily closed-circuit television and other readers incorporating a monitor or an LCD screen, which provide improved contrast and magnification.

How the intervention might work

Like many types of rehabilitation, low-vision rehabilitation includes heterogeneous interventions, which may have several components. Moreover, people who are prescribed a low-vision device usually receive training to use it. Several training techniques are employed, often using both office- and home-based exercises with the device for a few hours in different sessions. Overall, modern rehabilitation services tend to be provided by multidisciplinary services (Langelaan 2007). Besides prescription of LVAs and training on their use, especially focused on reading tasks, services can provide psychological support, home environmental assessment, and, for people of working age, social worker support. Moreover, different types of follow-up are provided, either in low-vision clinics or at home, by several types of professionals.

As was intended, this review concentrates on reading aids that magnify text, sometimes also improving its contrast.

Why it is important to do this review

The most suitable device depends on the person's needs and the visual functioning they have. Rehabilitation should be tailored to correspond to the type of visual loss and may also be modified by the individual's choice or expectations or by more general cultural demands (Dickinson 1998; Margrain 1999). Besides the level of magnification, there are other factors that are important when choosing an optical device, such as ease of use and cosmetic appearance. Devices may be rejected if they have an unusual cosmetic appearance that call attention to the person's disability.

Reading is an extremely complex visual task, which involves the integration of visual, cognitive, and motor processes. In everyday reading, it is important for people to achieve their optimal reading rate (measured usually in words per minute), and, for people with low vision, a speed that is sufficient to complete the task within an acceptable amount of time. The effect of slow reading on comprehension is variable, as low reading speed was found to decrease comprehension by Dickinson 1998 but not by Legge 1989.

Given the availability of a wide range of aids from simple magnifiers to high-power video magnifiers, all of which have advantages and disadvantages, an assessment of their effects on reading would be very useful.

Objectives

The objective of this review is to assess the effects of reading aids for adults with low vision. We consider reading aids that maximise the person's visual reading capacity, e.g. by increasing image magnification (optical and electronic magnifiers), augmenting text contrast (coloured filters), or trying to optimise the viewing angle or gaze position (such as prisms). We have not included studies investigating reading aids that allow reading through hearing, such as talking books or screen readers, or through touch, such as Braille-based devices. Finally, we did not consider rehabilitation strategies or complex low-vision interventions.

Methods

Criteria for considering studies for this review

Types of studies

We included randomised and quasi-randomised trials.

Types of participants

We included trials in which participants were aged 16 or over with low vision as defined by the study investigators. Where possible we grouped participants according to the type or cause of visual impairment.

Types of interventions

We included trials in which any device or aid used for reading visually was compared to another device or aid. This included non-electronic aids, i.e. optical devices such as magnifiers and telescopes, and electronic aids such as several types of closed circuit television (CCTV). These devices are rated in terms of the equivalent power measured in diopters, which allows devices to be compared to each other (Sloan 1971). We also considered other low-vision aids (LVAs) such as coloured filters and optical prisms, which are commonly prescribed in low-vision rehabilitation as they are supposed to improve reading in some people.

We excluded trials in which the intervention is a device to read though hearing, such as screen readers or talking books, or through touch, such as Braille-based devices.

Types of outcome measures

Using World Health Organization (WHO) language on Functioning, Disability and Health (accessed at WHO website on July 17th, 2011), maximum reading speed and reading acuity under ideal conditions of text magnification and contrast, such as when using the Minnesota Low-Vision Reading test (MNREAD), is the person's capacity. Capacity may be partly an individual trait (slow or fast reader) and can be limited by several visually and non-visually impairing diseases. Vision-based reading aids aim at maximising the person's performance by compensating their diminished visual function, especially by magnification. The choice of outcome measures in this review is driven by its emphasis on the vision-related component of performance.

Research on psychophysics of reading has shown that reading speed is typically stable across a range of print sizes (maximum reading speed) that are larger than a certain threshold (critical print size), whereas at smaller print sizes, below the critical print size, the reading speed slows and the reading acuity limit is reached (Ahn 1995a; Ahn 1995b; Legge 1985a; Legge 2007). Font size at critical print size is usually two or three times larger than reading acuity. A similar pattern is also found in most people with low vision (Legge 1985b; Legge 2007). A plot of reading speed against font size (adjusted by reading distance and expressed in logMAR) can be obtained using reading charts such as the MNREAD charts (Legge 2007). The following definitions developed by the authors of the MNREAD charts (Ahn 1995a) are adopted in the updated version of this review:

READING ACUITY: the smallest print that the person can read without making significant errors;
CRITICAL PRINT SIZE: the smallest print that the person can read with maximum speed;
MAXIMUM READING SPEED: the person's reading speed when reading is not limited by print size, i.e. for print size larger than the critical print size.

The issue of measuring reading performance in LVA research has been recently reviewed in Rubin 2013, He found that the methods for assessing reading performance and the algorithms for scoring reading tests need to be optimised so that the reliability and responsiveness of reading tests can be improved. A broader perspective on outcome measures, including quality of life measures, is also included in a systematic review on effectiveness of low vision service provision (Binns 2012).

Primary outcomes

In the 2013 update of this review, we decided to change our primary outcome, as defined in the original protocol (reading speed), by including print size in its definition in order to make it more similar to real-world tasks. The primary outcome for this updated version was reading speed in words per minute, recorded using typical point size (i.e. approximately 10 to 14 point size), in books or newspapers.

Maximum reading speed recorded across a range of point sizes, using MNREAD or Bailey-Lovie charts, was also accepted. However, it may be unclear, unless specified, whether maximum reading speed is achieved for common book text size with each reading aid. Thus, we rated studies reporting only maximum reading speed as providing indirect evidence regarding the primary outcome of this review.

Secondary outcomes

The review conclusions were based on the primary outcome, whereas secondary outcomes were mainly assessed for consistency with the primary outcome. Secondary outcomes include:

reading duration in minutes; defined as the time the person could read without visual discomfort causing the need to take a pause;
reading acuity in logMAR; because this is mostly a function of magnification, we analyse this outcome only if devices are matched by magnification (e.g. a difference between unmatched electronic and optical aids needs no demonstration);
ease and frequency of use as reported by the participants;
quality of life as measured by any validated scale that aims to measure the impact of visual function loss on quality of life;
reported adverse outcomes.

Search methods for identification of studies

Electronic searches

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) 2013, Issue 1, part of The Cochrane Library. www.thecochranelibrary.com (accessed 31 January 2013), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMED-LINE, (January 1950 to January 2013), EMBASE (January 1980 to January 2013), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to January 2013), OpenGrey (System for Information on Grey Literature in Europe) (www.opengrey.eu/), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov/) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 31 January 2013.

See: Appendices for details of search strategies for CENTRAL (Appendix 1), MEDLINE (Appendix 2), EMBASE (Appendix 3), LILACS (Appendix 4), OpenGrey (Appendix 5), mRCT (Appendix 6), ClinicalTrials.gov (Appendix 7) and the ICTRP (Appendix 8).

Searching other resources

We handsearched the British Journal of Visual Impairment from 1983 to 1999 and the Journal of Visual Impairment and Blindness from 1976 to 1991 for relevant trials. We searched the reference lists of relevant articles to find additional trials. We used the Science Citation Index to find articles that cited relevant articles. We contacted investigators and manufacturers of low-vision aids to identify other published and unpublished reports.

Data collection and analysis

Selection of studies

Two authors working independently assessed the titles and abstracts resulting from the electronic searches. We obtained the full copy of all relevant or potentially relevant trials and assessed these according to the ‘Criteria for considering studies for this review’. Only trials meeting these criteria were assessed for methodological quality. The authors were not masked to any trial details when making their assessments. We resolved disagreements about whether a trial should be included by discussion and consensus. We attempted to obtain additional information where necessary.

Data extraction and management

Two authors working independently extracted data using a form developed by the Cochrane Eyes and Vision Group using Chapter 7 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011a). We resolved any discrepancies by discussion. We contacted investigators to obtain missing data where necessary. For three studies, individual data were reported in tables of the publication. These were used for further analyses.

Assessment of risk of bias in included studies

Two authors working independently assessed trial quality according to the methods set out in Chapters 8 and 10 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011b; Sterne 2011). The following parameters were considered: method of allocation to treatment; allocation concealment (selection bias); documentation of exclusions and completenessof follow-up (attrition bias); selective outcome reporting (reporting bias). Masking of participants, study personnel (performance bias) and outcome assessors (detection bias) was not used in this review since it is not possible with most LVAs. Moreover, masking is meaningless for some outcomes, such as participant's preference for each device. We graded each parameter of trial quality as being at low, high or unclear risk of bias. We contacted study authors for clarification on any item graded as unclear. Authors were not masked to any trial details during the assessment.

Evaluation of cross-over-like studies was an issue in this review. Assessing the performance of the same participant who tries different LVAs is a common study design used by researchers into low vision, and is also known as a ‘within-subject’ design. This is an efficient design since we do not need to allow for all variations which occur between arms of parallel-group studies. In practice this means that, for the same number of participants, a cross-over design is likely to be more powerful. However, cross-over trials are not always appropriate. The most important consideration is whether the participants start the second period in a similar state to how they started the first period. If the characteristics of the participant have changed in some way by the time the second period starts, then the comparison of treatments is not fair, and there will be within-participant variation. Based on The Cochrane Collaboration's Open Learning Additional Module 2, (Alderson 2002) and on Chapter 16 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011c), the following questions should generally be addressed for a cross-over study:

Is the condition of the participants chronic and stable?
Does the intervention provide temporary relief, and not permanent change?
Can the outcome be repeated in the second period if it occurs in the first?
Might the effect of the first intervention last into the second treatment period?
Does the trial go on long enough for the LVA to be properly used?

In the 2013 update of this review, we applied the new ‘Risk of bias’ tool to rate methodological quality. Assessment of randomisation procedures requires consideration of two components: sequence generation and allocation concealment. A discussion among the authors led to grading both components in cross-over-like studies included in this review as being at low risk of bias. In fact, in low-vision studies adopting a cross-over-like design in this review, all participants used all devices and the order of presentation was randomised. We judged that two questions must be asked to rate the quality of randomisation and allocation in this type of study:

Does knowledge of the first LVA selected affect recruitment into the trial?
Does the order in which the LVAs are used affect the results?

Regarding question 1, the answer should be no, since knowing the order of LVA presentation in the study should not affect recruitment into the trial in studies in which testing with each device is carried out in the same session, which is often referred to by low-vision researchers as ‘within-subject’ design. As to question 2, we considered two additional items: 1) period effect, whether the condition can change during subsequent phases of testing of each device; 2) carry-over effect and period-by-treatment interaction, whether the effect on performance of using a specific device affects the performance of the following. These items will be contextu-alised in the ‘Results’ section.

Measures of treatment effect

We obtained the mean difference (MD) and the standard error (SE) of the MD, referred to as ‘SE (MD)’, when continuous data were available. We then used the generic inverse variance method when dealing with cross-over studies (Higgins 2011c); see also Appendix 9 for details and additional methods used.

Results were summarised in the Summary of Findings table using relative and absolute measures of effect, as recommended in Chapter 11 of the Cochrane Handbook for Systematic Reviews of Interventions (Schünemann 2011).

Methods for future updates to this review

The following methods will be used to analyse studies if sufficient data become available in future updates.

For dichotomous data, results will be expressed as odds ratio (OR) estimates or risk ratio (RR) estimates (with a 95% confidence interval (CI)). Odds ratios will be preferred when event probability is close to one, in order to avoid over-optimistic conclusions associated with RR estimate in such cases. The risk difference or the number needed to treat for an additional beneficial outcome will be obtained, with a 95% CI.

Unit of analysis issues

Participants, rather than eyes, are the unit of analysis in this review. Specific unit of analysis issues were found in studies comparing several devices on the same participant which we dealt with as described in other sections of this review and as shown in Appendix 9. Studies which measure outcome in the better eye will be included, whereas studies adopting eyes rather than individuals as the unit of analysis are excluded.

Dealing with missing data

There was only one parallel-arm trial in this review. Missing data for this study were enumerated for each treatment arm in the Characteristics of included studies table. The concept of missing data is more complex when several devices are tested on the same participant, since the participant may be able to read with some devices but not with others. These issues are related to study inclusion criteria and are discussed in the Results and Discussion sections.

Assessment of heterogeneity

If a sufficient number of studies are found for future updates of this review, we will assess heterogeneity using the I² statistic and its 95% confidence interval according to Chapter 9 of the Cochrane Handbook for Systematic Reviews of Interventions (Deeks 2011b).

Assessment of reporting biases

We considered reporting biases only for reading speed as the primary outcome, since we found it difficult to consider other outcomes not reported in the absence of standard measurements tools, relative to the specific aim of this review.

Data synthesis

We conducted data analysis using Chapter 8 of the Cochrane Handbook for Systematic Reviews of Interventions (Deeks 2011b). Since a cross-over design was found to be common in research on the effectiveness of LVAs, these studies were included in the review provided that the order of presentation of the devices was randomised or quasi-randomised and specific methods were used to deal with them. A number of minor statistical and data extraction issues arose from the fact that nine out of ten studies included in this review compared several devices on the same participant, e.g. methods to handle within-subject correlation and multiplicity of testing. Other items were small sample size issues, data skewness, and the availability of individual patient data in small studies. These items were dealt with using methods suggested in Elbourne 2002 and in Chapter 16 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011c), as summarised in Appendix 9. These statistical manipulations were based on methods that are unchanged from the first version of this review.

Subgroup analysis and investigation of heterogeneity

If enough studies are found in future updates of this review, we will assess the effect of low-vision severity (e.g. proportion of participants below 20/100 in the better eye), matching of LVAs by magnification versus no matching, participant age (e.g. proportion of people aged 55 years or more), study design (parallel-arm versus ‘within-subject’).

Sensitivity analysis

If a sufficient number of studies are found in future updates, we will conduct sensitivity analyses with the following adjustments:

excluding studies of lower methodological quality (scoring high risk of bias on any parameter of quality);
excluding unpublished studies.

Results

Description of studies

Results of the search

The electronic searches run in July 2006 revealed 488 reports of trials. We screened the titles and abstracts and identified 20 studies which appeared relevant. We obtained full-text copies of these reports and after further assessment we included nine studies and excluded the remaining 11 studies (Figure 1).

Results from searching for studies for inclusion in the review.

An update search run in January 2013 identified 528 references. The Trials Search Co-ordinator removed 150 duplicates, scanned 378 references and removed 64 records which were not relevant to the scope of the review. We screened 314 references and obtained full-text reports of eight studies; after assessment these studies were excluded. While this review was being updated, we retrieved studies in low-vision research which are conference abstracts. Currently we are unable to identify six full-text reports of studies or make contact with the trialists. Relevant sections from the conference abstracts are shown in the Characteristics of studies awaiting classification. If we are able to collect sufficient data we will assess these studies for potential inclusion in further updates. In addition, handsearching references of other reports used for this review found two studies published in 2005, of which Watson 2005 is now included and Kaida 2005 is under assessment awaiting contact from the author.

Included studies

We included 10 studies in the review (see Characteristics of included studies). A summary of the studies is given below including their methodological quality assessment, which is presented graphically in Figure 2. Interventions, outcome measures and their measurement tools were very variable and are summarised in Table 1.

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

Table 1. Description of outcomes in studies.

Study	LVAs compared	RS measurement	Reading acuity	Reading duration	Subjective preference for specific devices	Quality of life	Other outcomes reported but not included in this review
Culham 2004	4 electronic head-mounted versus participant's aids or spectacles	Small (N5), typical medium (N10) and large (N20) print size	Bailey-Lovie charts				Reading accuracy, contrast sensitivity (Pelli Robson), daily living tasks: grocery identification (seconds), writing checks (seconds)
Eperjesi 2004	Coloured versus clear filter overlays	Rate of Reading Test (print size 4- to 18-point)	not available, but not relevant for filters which do not magnify text
Goodrich 2001	Hand-held CCTV, stand-mounted CCTV versus prescribed optical aid	1M text (typical print size at 40 cm)		Cumulative time spent reading	Questions on subjective preference		Reading comprehension
Kleweno 2001	Head-mounted display versus standard CCTV	Next largest size close to near acuity (MNREAD electronic version)	MNREAD charts		Single question on preference in terms of brightness and clarity		Different contrast/colour condition for cathode ray tube or virtual retinal display
Ortiz 1999	Head-mounted display (LVES) versus CCTV	News articles MNREAD	MNREAD charts				Reading comprehension
Peterson 2003	Head-mounted display, handheld CCTV, standard CCTV versus the participant's optimum conventional optical magnifier	MNREAD reading speed across several print sizes available in figure	MNREAD-like charts		Single question on subjective ease of use of each magnifier on a 5-step scale		Ability to read specific print sizes (0.2 - 1.0 log-MAR); navigate a text, follow a route on a map, reading medicine bottle label
Spitzberg 1995	Mirror, prism or zoom optical magnifiers versus conventional magnifier (same magnification)	1M or 1.5M print (ordinary print size at 40 cm)			Preference for a specific device		Note: magnification was standardised at 3x for all devices
Smith 2005	Custom or standard bilateral prism spectacles versus conventional spectacles	MNREAD reading speed “at the critical print size”	MNREAD charts		MLVQ measuring helpfulness and use	NEI-VFQ25, MLVAI
Stelmack 1991	CCTV, illuminated stand magnifier, spectacles	Readers Digest (silent reading)		Reading time without visual discomfort			Reading comprehension
Watson 2005	Hybrid-diffractive spectacle magnifier compared with a refractive spectacle magnifier and an aplanatic spectacle magnifier (2 separate experiments)	MNREAD maximum RS with each reading aid; Pepper Visual skills for Reading Test	MNREAD charts		Self report of satisfaction with reading using a visual analogue scale		Reading accuracy, Morgan Low Vision reading Comprehension Assessment

Electronic device (various types of CCTV) versus optical device for adults with low vision
Patient or population: Adults with low vision Settings: Intervention: Electronic device (various types of CCTV) Comparison: Optical device
Outcome: reading speed in words per minute (wpm) Comparison subgroups	Illustrative comparative risks^* (95% CI)		No of Participants (studies)	Quality of the evidence (GRADE)	Studies
	Assumed risk	Corresponding risk
	Optical device	Electronic device (various types of CCTV) versus optical device
Stand-mounted CCTV versus best prescribed optical device	The mean reading speed in the control group (best prescribed optical device) was 64 words per minute	The mean reading speed (words per minute) using a stand-mounted CCTV was 12 higher (2.51 lower to 26.51 higher)	22 (1 study)	⊕⊕○○ low¹^,²^,³	Goodrich 2001
Stand-mounted CCTV versus participant's optical device	The mean reading speed in the control group (participant's optical device) was 65.8 words per minute	The mean reading speed (words per minute) using a stand-mounted CCTV was 45.5 higher (25.07 lower to 65.03 higher)	70 (1 study)	⊕⊕○○ low¹^,²^,³^,⁴	Peterson 2003
Mouse-based device (27” TV monitor) versus optical device	The mean reading speed using an optical device was 64 words per minute	The mean reading speed using a mouse-based device (27”TV monitor) was 15.8 higher (0.42 to 31.18 higher)	22 (1 study)	⊕⊕○○ low¹^,²^,³	Goodrich 2001
Mouse-based device (14” monitor) versus participant's optical device	The mean reading speed in the control group (participant's optical device) was 65.8 words per minute	The mean reading speed using a mouse-based device (14” monitor) was 40.5 higher (23.71 to 57.29 higher)	70 (1 study)	⊕⊕⊕○ low ¹^,²^,³^,⁴	Peterson 2003
Flipperport head-mounted CCTV (table stand camera) versus optical device	The mean reading speed (words per minute) using an optical device was 95 words per minute	The mean reading speed using a Flipperport head-mounted CCTV (table stand camera) was 24.6 lower (40.88 to 8.32 lower)	20 (1 study)	⊕⊕⊕○ moderate¹^,²	Culham 2004
Jordy head-mounted CCTV versus optical device	The mean reading speed (words per minute) using an optical device was 95 words per minute	The mean reading speed using Jordy head-mounted CCTV was 33.7 lower (50.34 to 17.06 lower)	20 (1 study)	⊕⊕⊕○ moderate¹^,²	Culham 2004
Maxport head-mounted CCTV versus optical device	The mean reading speed (words per minute) using an optical device was 95 word per minute	The mean reading speed using Maxport head-mounted CCTV was 29.4 lower (45.74 to 13.06 lower)	20 (1 study)	⊕⊕⊕○ moderate¹^,²	Culham 2004
NuVision head-mounted CCTV versus optical device	The mean reading speed (words per minute) using an optical device was 95 word per minute	The mean reading speed using NuVision head-mounted CCTV was 40 lower (56 to 23.3 lower)	20 (1 study)	⊕⊕⊕○ moderate¹^,²	Culham 2004
Outcome: Reading duration (minutes) Comparison: stand CCTV versus optical device	The mean reading duration (minutes) in the control groups was 23 minutes	The mean reading duration (minutes) in the intervention groups was 13.7 higher (7.9 higher to 19.5 higher)	22 (1 study)	⊕⊕⊕○ moderate¹^,²	Goodrich 2001
Outcome: Reading duration (minutes) Comparison: stand CCTV versus optical device	The mean reading duration (minutes) in the control groups was 23 minutes	The mean reading duration (minutes) in the intervention groups was 12.8 higher (9.3 higher to 16.3 higher)	22 (1 study)	⊕⊕⊕○ moderate¹^,²	Goodrich 2001

Stand-based closed-circuit television (CCTV) versus head-mounted electronic device (HMD) for adults with low vision
Patient or population: Adults with low vision Settings: Intervention: Stand-based closed-circuit television (CCTV) versus head-mounted electronic device (HMD)
Outcomes	Illustrative comparative risks^* (95% CI)		No of Participants (studies)	Quality of the evidence (GRADE)	Studies
	Assumed risk	Corresponding risk
	Control	Stand-based closed-circuit television (CCTV) versus head-mounted electronic device (HMD)
Reading Speed (words per minute MNREAD Charts	The mean reading speed in the control groups was 66 word/minute	The mean reading speed in the intervention groups was 3.13 higher (3.47 lower to 9.73 higher)	93 (3 studies)	⊕⊕○○ low¹^,²^,³^,⁴	Ortiz 1999; Kleweno 2001; Peterson 2003
Reading acuity (logMAR) MNREAD charts	The mean reading acuity in the control groups was 1.50 logMAR	The mean reading acuity in the intervention groups was 0 higher (-0.03 to 0.03 higher)	13(1 study)	⊕⊕⊕○ moderate¹^,²	Kleweno 2001

	Diffractive spectacle mounted magnifiers compared to control for adults with low vision
	Patient or population: Adults with low vision Settings: Intervention: Diffractive spectacle-mounted magnifiers Comparison: Control
Comparison	Outcomes	Illustrative comparative risks^* (95% CI)		No of Participants (studies)	Quality of the evidence (GRADE)	Studies
		Assumed risk	Corresponding risk
		Control	Diffractive spectacle mounted magnifiers
Diffractive versus refractive-aspheric spectacle magnifier	MNREAD maximum reading speed (words/minute)	The mean maximum reading speed using refractive-aspheric spectacle magnifier was 99 words per minute	The mean maximum reading speed using diffractive spectacle magnifier was 0.94 lower (16.56 lower to 14.68 higher)	15 (1 study)	⊕○⊕○ low¹^,²^,³	Watson 2005
	MNREAD critical print size (M print size)	The mean critical print size using refractive-as-pheric spectacle magnifier was 1.17 logMAR	The mean critical print size using diffractive spectacle magnifier was 0.10 lower (0.25 lower to 0.05 higher)	15 (1 study)	⊕⊕○○ low¹^,²^,³	Watson 2005
	Morgan Low Vision Reading Comprehension Assessment	The mean reading comprehension using refractive-aspheric spectacle magnifier was 11.1 score	The mean reading comprehension using diffractive spectacle magnifier was 1.98 higher (0.67 to 3.29 higher)	15 (1 study)	⊕⊕○○ low¹^,²^,³	Watson 2005
Diffractive versus apla-natic spectacle magnifier	MNREAD maximum reading speed (words/minute)	The mean maximum reading speed using apla-natic spectacle magnifier was 110 words per minute	The mean maximum 15 reading speed using (1 study) diffractive spectacle magnifier was 2.6 higher(11.88 lower to 17.08 higher)	15 (1 study)	⊕⊕○○ low¹^,²^,³	Watson 2005
	MNREAD critical print size (M print size)	The mean critical print size using aplanatic spectacle magnifier was 1.03 logMAR	The mean critical print 15 size using diffractive (1 study) spectacle magnifier was 0.19 lower (0.40 lower to 0.02 higher)	15 (1 study)	⊕⊕○○ low¹^,²^,³	Watson 2005
	Morgan Low Vision Reading Comprehension Assessment	The mean reading comprehension using aplanatic spectacle magnifier was 13.5 score	The mean reading com- 15 prehension using diffrac- (1 study) tive spectacle magnifier was 0.76 lower (1.98 lower to 0.46 higher)	15 (1 study)	⊕⊕○○ low¹^,²^,³	Watson 2005

Overlay coloured filters versus clear filter for adults with low vision
Patient or population: Adults with low vision Settings: Intervention: Overlay coloured filters Comparison: Clear filter
Outcome: reading speed (words per minute) Filter colour	Illustrative comparative risks^* (95% CI)		No of Participants (studies)	Quality of the evidence (GRADE)	Study
	Assumed risk	Corresponding risk
	Control	Overlay coloured filters versus clear filter
Rose filter	The mean reading speed (words perminute) using clear filter was 84 words per minute	The mean reading speed using rose filter was 9 lower (-24 lower to 6 higher)	13 (1 study)	⊕⊕○○ low¹^,²^,³	Eperjesi 2004
Pink filter	The mean reading speed (words perminute) using clear filter was 84 words per minute	The mean reading speed using pink filter was 9 lower (-15 lower to -3 lower)	13 (1 study)	⊕⊕○○ low¹^,²^,³	Eperjesi 2004
Yellow filter	The mean reading speed (words perminute) using clear filter was 84 words per minute	The mean reading speed using yellow filter was 7 lower (20 lower to 6 higher)	13 (1 study)	⊕⊕○○ low¹^,²^,³	Eperjesi 2004
Orange filter	The mean reading speed (words perminute) using clear filter was 84 words per minute	The mean reading speed using orange filter was 13 lower (29 lower to 2 higher)	13 (1 study)	⊕⊕○○ low¹^,²^,³	Eperjesi 2004
Mint filter	The mean reading speed (words per minute) using clear filter was 84 words per minute	The mean reading speed using mint filter was 8 lower (17 lower to 2 higher)	13 (1 study)	⊕⊕○○ low¹^,²^,³	Eperjesi 2004
Lime filter	The mean reading speed (words per minute) using clear filter was 84 words per minute	The mean reading speed using rose filter was 6 lower (23.73 lower to 5.73 higher)	13 (1 study)	⊕⊕○○ low¹^,²^,³	Eperjesi 2004
Gray filter	The mean reading speed (words per minute) using clear filter was 84 words per minute	The mean reading speed using grey filter was 4 lower (25 lower to 17 higher)	13 (1 study)	⊕⊕○○ low¹^,²^,³	Eperjesi 2004
Blue filter	The mean reading speed (words per minute) using clear filter was 84 words per minute	The mean reading speed using blue filter was 12 lower (24 lower to 1 higher)	13 (1 study)	⊕⊕○○ low¹^,²^,³	Eperjesi 2004
Aqua filter	The mean reading speed (words per minute) using clear filter was 84 words per minute	The mean reading speed using aqua filter was 9 lower (15 lower to 3 lower)	13 (1 study)	⊕⊕○○ low¹^,²^,³	Eperjesi 2004
Purple filter	The mean reading speed (words per minute) using clear filter was 84 words per minute	The mean reading speed using rose filter was 14 lower (25 lower to 3 lower)	13 (1 study)	⊕⊕○○ low¹^,²^,³	Eperjesi 2004

Methods	Randomised presentation of devices. First, the clinician determined as many unique combinations of the order of showing each device and listed them. Second, an independent non-clinician was then asked to randomly rearrange the order of the possible combinations on the list. On completion of the clinical evaluation participants were loaned 2 of the electronic devices, each for a period of 1 week, for use at home. The devices were allocated randomly. Masking: Participant - masking issues are not described but the study participants were likely to be unmasked given the use of recognisable devices. Provider - same as above; Outcome - same as above. Exclusions after randomisation: None reported. Losses to follow-up: None reported. Unusual study design: Within-subject design, i.e. a cross-over study in which all participants try all 4 devices. After training the use is restricted to 2 devices per participant
Participants	Country: UK Number randomised: 10 individuals with AMD and 10 with EOMD were recruited from the low-vision clinic and specialist medical clinics at Moorfields Eye Hospital. Age: EOMD group: 21 - 57 (mean 41.8 years); AMD group: 54 - 82 (mean 73.5 years). Sex: 11 women, 9 men. Inclusion criteria: (1) English-speaking and prepared to attend 5 appointments; (2) visual acuity between 6/18 and 1/60 in the better eye and stable vision for at least 3 months; (3) to be experienced in the use of optical LVAs (i.e. for 1 year or more); (4) prior to recruitment all participants had to have received standard hospital care and any medical intervention required had been completed. Exclusion criteria: any co-existing conditions which may have affected the handling of devices or performance with them
Interventions	Treatment: 4 types of head-mounted electronic devices (HMDs): Flipperport, Jordy, Maxport, and NuVision. Participants' own spectacles were used with the HMDs when appropriate Control: habitual spectacle correction for distance with a +1.50 addition for intermediatedistance and a +4.00 addition for near, as required, depending on accommodative ability previously prescribed low-vision device Duration: 1 week.
Outcomes	Use of the devices for a range of clinical and practical visual tasks. Assessment was based on clinical and practical visual tasks measured in the laboratory. On completion of the clinical evaluation, devices were also loaned to participants for use in their habitual environments for a period of 1 week, on a random basis. Reading speed and accuracy using passages of text. Three print sizes were used: N5 (i.e. comparable with medicine bottle labels), N 10 (standard newsprint) and N 20(small newspaper headlines). Performance on 2 intermediate distance visual tasks: a) time to complete, sign and date a cheque; b) time to locate and touch 2 grocery items from an assembled collection of 15 products on a shelf
Notes
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomised presentation of devices; although no further detail was given on how randomisation sequence was generated, selection bias should be avoided since all participants used all devices (cross-over study design)
Allocation concealment (selection bias)	Low risk	Randomised presentation of devices; although no further detail was given on how randomisation sequence was concealed, selection bias should be avoided since all participants used all devices (cross-over study design)
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow-up reported
Selective reporting (reporting bias)	Low risk	No protocol available, but primary outcome reported
Period effect	Low risk	Stable vision required during the last 3 months to include participants
Carry-over effect and period-by-treatment interaction	Unclear risk	No details reported
Other bias	Low risk	No other bias identified

Methods	Method of allocation: It is reported that “the filters were presented randomly“, but no description of the methods is provided. Masking: Participant - masking issues are not described, but the study was likely to be unmasked given the use of recognisable coloured filters; Provider - same as above; Outcome - same as above. Exclusions after randomisation: None reported. Losses to follow-up: None reported. Unusual study design: Within-subject design, i.e. a cross-over study in which all participants try all 10 coloured overlay filters and the control clear one
Participants	Country: UK Number randomised: 12 consecutive participants were recruited over a 3-month period from the Focus on Blindness Low Vision Centre in Birmingham, a charitable voluntary organisation. Age: mean age 81 years, SD: 5.07 years. Sex: 9 women, 3 men. Inclusion criteria: (1) non-exudative AMD resulting in a relative scotoma with central fixation. Exclusion criteria: (1) near working reading acuity poorer than logMAR 1.00 (approximately equivalent to large print); (2) crystalline opacities greater than grade 1 on the Lens Opacity Classification System; (3) participants undergoing ophthalmological treatment
Interventions	Treatment: 10 different coloured light filter overlays (Intuitive Overlays) (figures in brackets are percentage transmission values); rose (78%); pink (78%); purple (67%); aqua (81%); blue (74%); lime-green (86%); mint-green (85%); yellow (93%); orange (83%); grey (71%) Control: a clear overlay (Roscolene # 00) (360 cdm-2) with 100% transmittance Duration: single test session
Outcomes	Reading rate calculated as the number of correct words per minute measured with the Rate of Reading Test (printed, nonsense, lower case sans serif, stationary text)
Notes	Tomeasure reading rate, tape recordings were replayed after each testing session and each participant scored by measuring the total time taken to read each block of test print and noting the errors on a score sheet
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomised presentation of devices; although no further detail was given on how randomisation sequence was generated, selection bias should be avoided since all participants used all devices (cross-over study design)
Allocation concealment (selection bias)	Low risk	Randomised presentation of devices; although no further detail was given on how randomisation sequence was concealed, selection bias should be avoided since all participants used all devices (cross-over study design)
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow-up or exclusion after randomisation reported
Selective reporting (reporting bias)	Low risk	No protocol available, but primary outcome reported
Period effect	Low risk	Participants with non-exudative AMD were included who are expected to have stable vision in the study period
Carry-over effect and period-by-treatment interaction	Unclear risk	No details reported
Other bias	Low risk	No other bias identified

Methods	Method of allocation: Randomisation was not used but the order of presentation of the devices was rotated for consecutive participants (quasi-random assignment). Masking: Participant - masking issues are not described but the study was likely to be unmasked given the use of recognisable devices. Provider - same as above; Outcome - same as above Exclusions after randomisation: none reported. Losses to follow-up: none reported. Unusual study design: Within-subject design, i.e. a cross-over study in which all participants try the devices consecutively
Participants	Country: USA Number randomised: 22 veterans enrolled in the residential rehabilitation programme of the Western Blind Rehabilitation Center (none with previous reading training). Age: mean 73 (range: 53 - 87) years Sex: 20 men, 2 women. Inclusion criteria: (1) legal blindness; (2) central scotoma with a intact peripheral field; (3) stated desire for reading rehabilitation. Exclusion criteria: (1) cognitive deficits or current use of medication that would impair reading ability; (2) illiteracy
Interventions	5 days “hands-on” training with each of the 3 types of devices (the prescribed optical device considered as control). Eccentric viewing training preceded reading training. Treatment: stand-mounted CCTV, hand-held CCTV using a 27-inch television. Control: prescribed optical device (stand magnifier n = 19; microscopic lenses n = 3). Duration: 15 training sessions plus sessions needed for evaluation
Outcomes	Reading speed using paragraphs of 250 words in Times New Roman (1 M font) with 5th-grade difficulty reading comprehension assessed with 5 question for each paragraph; Reading duration during each training session; Participants' preferences for a specific device with forced and open-ended questions
Notes
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quasi-randomised study: the order of presentation of the devices was rotated for consecutive participants; despite this, selection bias should be avoided since all participants used all devices (cross-over nature of the study design)
Allocation concealment (selection bias)	Low risk	Order of randomisation can be foreseen because rotation was used; despite this, selection bias should be avoided since all participants used all devices (cross-over nature of the study design)
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow-up or exclusion after randomisation reported
Selective reporting (reporting bias)	Low risk	No protocol available, but primary outcome reported
Period effect	Unclear risk	No details reported
Carry-over effect and period-by-treatment interaction	Unclear risk	No details reported
Other bias	Low risk	No other bias identified

Methods	Method of allocation: The order of acuity testing in terms of viewing the standard cathode ray tube (CRT) monitor or the Virtual Retinal Display (VRD) first was randomised. The method is not described. Masking: Participant - masking issues are not described but the study should be unmasked given the use of recognisable devices; Provider - same as above; Outcome - same as aboveExclusions after randomisation: 2 participants removed from the study (1 requested to be withdrawn from the testing because of fatigue, 1 was unable to locate the VRD exit pupil and maintain a stable image on the small functional portions of peripheral retina). Losses to follow-up: None reported. Unusual study design: Within-subject design, i.e. a cross-over study in which all participants try the 2 devices consecutively
Participants	Country: USA Number randomised: 13 low-vision volunteers selected to represent the broad range of partially sighted individuals actively involved in the work force. Age: 28 - 59 years with a mean age of 41.2 years (SD 10.3). Sex: not reported. Inclusion criteria: either actively employed or in graduate school. Exclusion criteria: none.
Interventions	Treatment: the VRD scans modulated, low-power laser light to form bright, high-contrast, and high-resolution images directly onto the retina, a technology underlying the scanning laser ophthalmoscope (SLO). Each participant was given a reading speed test comprising 2 different test conditions: viewing a VRD image with a lower-power setting (1.27 mW) and viewing a VRD image with a higher-power setting (2.45 mW) Control: viewing a CRT with 2 test conditions: viewing a CRT with white letters on a black background, and viewing a CRT with red letters on a black background. The CRT red-on-blackcontrast condition was used to more closely match the CRT wavelength with themonochrome red VRD. Duration: single test session.
Outcomes	Reading speed, measured with a unique reading speed test based on the MinnesotaLow-Vision Reading test (MNRead™). 3 words at a time were presented to the participant in an unrelated manner. Subjective preference for 1 of the devices: at the conclusion of the reading tests,participants were asked to rate the VRD as “better, the same, or worse than the CRT” in terms of perceived brightness and perceived clarity
Notes
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomised presentation of devices; although no further detail was given on how randomisation sequence was generated, selection bias was likely to be avoided since all participants used all devices (cross-over nature of the study design)
Allocation concealment (selection bias)	Low risk	Randomised presentation of devices; although no further detail was given on how randomisation sequence was concealed, selection bias should be avoided since all participants used all devices (cross-over study design)
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow-up or exclusion after randomisation reported
Selective reporting (reporting bias)	Low risk	No protocol available, but primary outcome reported
Period effect	Unclear risk	No details reported
Carry-over effect and period-by-treatment interaction	Unclear risk	No details provided. They used a reading test based on the MNREAD, which has short duration. Nonetheless, 1 participant withdrew because of fatigue
Other bias	Low risk	No other bias identified

Methods	Method of allocation: The order of presentation of the devices is reported to be counterbalanced across participants. It is assumed that this equals rotation or quasi-random assignment but it is not reported if randomisation was used. Masking: Participant -masking issues are not described but the study should be unmasked given the use of recognisable devices; Provider - same as above; Outcome - same as above Exclusions after randomisation: none reported. Losses to follow-up: none reported. Unusual study design: Within-subject design, i.e. a cross-over study in which all participants try the devices consecutively
Participants	Country: USA Number randomised: 10 Age: mean 47 (24 - 79) years. Sex: not reported. Inclusion criteria: proficient CCTV users. Exclusion criteria: none reported.
Interventions	Treatment: Head-mounted video magnifier called Low Vision Enhancement System (LVES). Control: CCTV. Duration: Not reported.
Outcomes	Reading performance measured with an MNREAD Chart: reading speed; critical print size; reading acuity. News article reading: 7 articles for each device randomly chosen form a pool of 45. Reading comprehension asmeasuredwithmultiple choice questions about the article's content
Notes
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quasi-randomised study: the order of presentation of the devices was rotated (counterbalanced) for consecutive participants; even so, selection bias should be avoided since all participants used all devices (crossover study design)
Allocation concealment (selection bias)	Low risk	Order of randomisation can be foreseen because rotation was used; despite this, selection bias was likely to be avoided since all participants used all devices (cross-over study design)
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow-up or exclusion after randomisation reported
Selective reporting (reporting bias)	Low risk	No protocol available, but primary outcome reported
Period effect	Unclear risk	No details reported
Carry-over effect and period-by-treatment interaction	Unclear risk	Authors reported they could not find a practice effect comparing the first and the last half of their tests, nor a decay of performance, but a quantitative assessment was not available
Other bias	Low risk	No other bias identified

Methods	Method of allocation: Each magnifying device was presented in a random order to participants; theywere asked to complete (also in a randomorder) a series of 4 tests chosen specifically to replicate daily living tasks. Methods of randomisation are not described. Masking: Participant -masking issues are not described but the study should be unmasked given the use of recognisable devices. Provider - same as above; Outcome - same as above Exclusions after randomisation: none reported. Losses to follow-up: none reported. Unusual study design: Within-subject design, i.e. a cross-over study in which all participants try the devices consecutively
Participants	Country: UK Number randomised: 70 Age, Sex: 35 men with mean age: 68.3 (SD: 22.8) years and 35 women with mean age: 71.8 (SD: 20.6) years. Inclusion criteria: consecutive visually impaired participants. Each had previously undergone ophthalmologic care and a full low-vision examination including optimization of their refraction and their optical magnifier. Minimum magnification for comfortable reading of the participants' chosen print size was prescribed. Exclusion criteria: none.
Interventions	Treatment: various electronic vision enhancement systems (EVES) vs the subject's optimum conventional optical magnifier for near task. Optical magnifiers were a hand magnifier (n. 24), a stand magnifier (n. 45), and high-powered reading glasses (n. 1) with an average nominal magnification (lens dioptric power divided by 4) of 5.7 times (range, 2.0 - 14.7 times). EVES were: mouse-based with the image viewed at a fixed distance of 40 cm on a 14” monitor; mouse-based with the image viewed on a HMD unit; stand-based EVES with the image viewed at a fixed distance of 40 cm on a 14” monitor (images were black on white)
Outcomes	After an explanation, demonstration and a 2-minute active training period with each magnifying device the participants were asked to complete a series of 4 tests chosen to replicate daily living tasks: Reading speed and acuity (using adapted MNREAD charts); Time taken to track from 1 column of print to the next; Time taken to follow a route on a map and locate a specific feature; Time taken to identify specific information from a medicine bottle label. 4 versions of each task, equal in difficulty (in terms of number, length, and difficulty of words and page distance), were constructed and used in a randomised order to control fatigue effects
Notes
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomised presentation of devices; although no further detail was given on how the randomisation sequence was generated, selection bias should be avoided since all participants used all devices (crossover study design)
Allocation concealment (selection bias)	Low risk	Randomised presentation of devices; although no further detail was given on how randomisation sequence was concealed, selection bias was likely to be avoided since all participants used all devices (cross-over study design)
Incomplete outcome data (attrition bias) All outcomes	High risk	Not all participants could read using all devices; thus, the analysis is not intention-to-treat
Selective reporting (reporting bias)	Low risk	No protocol available, but primary outcome reported
Period effect	Unclear risk	No details reported
Carry-over effect and period-by-treatment interaction	Unclear risk	Authors reported they used reading and real-word tests of very short duration, but no quantitative details are available
Other bias	Low risk	No other bias identified

Outcome or subgroup title	No. of studies	Statistical method	Effect size
1 MNREAD maximum reading speed (words per minute)	1	Mean Difference (Fixed, 95% CI)	Totals not selected
1.1 Diffractive versus refractive-aspheric spectacle magnifier	1	Mean Difference (Fixed, 95% CI)	0.0 [0.0, 0.0]
1.2 Diffractive versus aplanatic spectacle magnifier	1	Mean Difference (Fixed, 95% CI)	0.0 [0.0, 0.0]
2 MNREAD critical print size (M print size)	1	Mean Difference (Fixed, 95% CI)	Totals not selected
2.1 Diffractive versus refractive-aspheric spectacle magnifier	1	Mean Difference (Fixed, 95% CI)	0.0 [0.0, 0.0]
2.2 Diffractive versus aplanatic spectacle magnifier	1	Mean Difference (Fixed, 95% CI)	0.0 [0.0, 0.0]
3 Morgan Low Vision Reading Comprehension Assessment	1	Mean Difference (Fixed, 95% CI)	Totals not selected
3.1 Diffractive versus refractive-aspheric spectacle magnifier	1	Mean Difference (Fixed, 95% CI)	0.0 [0.0, 0.0]
3.2 Diffractive versus aplanatic spectacle magnifier	1	Mean Difference (Fixed, 95% CI)	0.0 [0.0, 0.0]

Outcome or subgroup title	No. of studies	Statistical method	Effect size
1 Reading speed (words per minute)	1	Mean difference (Fixed, 95% CI)	Totals not selected
1.1 Rose filter	1	Mean difference (Fixed, 95% CI)	0.0 [0.0, 0.0]
1.2 Pink filter	1	Mean difference (Fixed, 95% CI)	0.0 [0.0, 0.0]
1.3 Yellow filter	1	Mean difference (Fixed, 95% CI)	0.0 [0.0, 0.0]
1.4 Orange filter	1	Mean difference (Fixed, 95% CI)	0.0 [0.0, 0.0]
1.5 Mint filter	1	Mean difference (Fixed, 95% CI)	0.0 [0.0, 0.0]
1.6 Lime filter	1	Mean difference (Fixed, 95% CI)	0.0 [0.0, 0.0]
1.7 Gray filter	1	Mean difference (Fixed, 95% CI)	0.0 [0.0, 0.0]
1.8 Blue filter	1	Mean difference (Fixed, 95% CI)	0.0 [0.0, 0.0]
1.9 Aqua filter	1	Mean difference (Fixed, 95% CI)	0.0 [0.0, 0.0]
1.10 Purple filter	1	Mean difference (Fixed, 95% CI)	0.0 [0.0, 0.0]

Methods	Participants were allocated using computer-generated randomisation codes prepared in advance. Randomisation and the ordering of spectacles were performed by a principal investigator who had no contact with participants during the study. Masking: Participant: yes Provider: no; Outcome: yes. Exclusions after randomisation: None reported. Losses to follow-up: 10 in the custom prism group, 6 in the standard prism group, and 2 in the placebo group
Participants	Country: UK Number randomised: 243 individuals with AMD at Manchester Royal Eye Hospital,England. Age: mean 81 years Sex: women 65% Inclusion criteria: English-speaking. Exclusion criteria: illiterate, resident in a hospital or a nursing home. Study duration: 3 months follow-up during the period July 15, 2001, through March31, 2003
Interventions	Treatment: 3 types of test spectacles: custom, incorporating bilateral prisms to match participants' preferred power and base direction; standard, incorporating standard bilateral prisms (6 prism diopters base in for logMAR VA of 0.48 - 1.00 and 10 prism diopters base in for logMAR VA of 1.02 - 1.68); placebo, consisting of spectacles matched in weight and thickness to prism spectacles but without the prism. The spectacles prescribed to each group included the optimal refractive correction for distance and near vision
Outcomes	logMAR visual acuity with ETDRS chart. Reading speed and critical print size with an MNREAD chart. National Eye Institute Visual Functioning Questionnaire (NEI-VFQ-25). Melbourne Low-Vision ADL (Activities of Daily Living) Index (MLVAI), part 1 consisting of the performance of 16 typical ADL dependent on vision assessed for speed, accuracy, and independence of performance, and part 2 consisting of a questionnaire. Manchester Low VisionQuestionnaire23 (MLVQ) with itemsmeasuring helpfulness and use of test spectacles
Notes
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants were allocated to a group using computer-generated randomisation codes prepared in advance
Allocation concealment (selection bias)	Low risk	Randomisation and the ordering of spectacles were performed by a principal investigator who had no contact with participants during the study
Incomplete outcome data (attrition bias) All outcomes	Low risk	Low number of losses to follow-up: 10 in the custom prism group, 6 in the standard prism group, and 2 in the placebo group
Selective reporting (reporting bias)	Low risk	No protocol available, but primary outcome reported
Other bias	Low risk	No other bias identified

Methods	Method of allocation: quasi-randomisation obtained by systematically rotating the order of presentation of the devices among participants. Masking: Participant - masking issues are not described but the study was likely to be unmasked given the use of recognisable devices; Provider - same as above; Outcome: same as above. Exclusions after randomisation: none reported. Losses to follow-up: none reported. Unusual study design: Within-subject design, i.e. a cross-over study in which all participants try the devices consecutively
Participants	Country: USA Number randomised: 39 from 5 low-vision clinics. Age: 9 - 77 years. Sex: not reported. Inclusion criteria: All participants were selected based on a need to use 3x magnification to read 1.0 M or 1. 5 M print. Exclusion criteria: None reported.
Interventions	Each participant trained dailywith 4 low-vision aids including at least 2 prototype devices for a minimum of 5 days. All participants practiced reading for 1 hour each day using materials developed for the study. Treatment: 4 new stand magnifiers with equivalent power: Spherical mirror magnifier covering 1 whole column width of newsprint; Cylindrical mirror magnifier covering one whole page width; reflecting prism magnifier with a 45 degree viewing angle; Zoom magnifier. Control: common stand magnifiers of the same power. Duration: 10 days.
Outcomes	Reading speed; Preference for each device including reporting detailed information on their looks, clarity, portability, comfort, ease of use, field and glare
Notes
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quasi-randomised study: the order of presentation of the devices was rotated (counterbalanced) for consecutive participants; even so, selection bias should be low since all participants used all devices (cross-over study design)
Allocation concealment (selection bias)	Low risk	Order of randomisation can be foreseen because rotation was used; despite this, selection bias should be low since all participants used all devices (cross-over study design)
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow-up or exclusion after randomisation reported
Selective reporting (reporting bias)	Low risk	No protocol available, but primary outcome reported
Period effect	Unclear risk	No details reported
Carry-over effect and period-by-treatment interaction	Unclear risk	No details reported
Other bias	Low risk	No other bias identified

Methods	Method of allocation: The VA Cooperative Studies Center generated the randomization sequence and the code envelopes for randomising the order of device presentation. The set of envelopes was handed to the investigators at the beginning of the study. The research assistant opened an envelope at the time needed to assign the treatment order. Methods for the randomisation sequence: the 6 different possible orders of presentation of the devices were numbered in advance. A list of random numbers was computergenerated. The 7, 8, 9 and 0 were deleted and the remaining numbers used to identify the group (information provided by investigators). Masking: Participant - masking issues are not described, but the study should be unmasked given the use of recognisable devices; Provider: same as above; Outcome - same as above. Exclusions after randomisation: none reported. Losses to follow-up: none reported. Unusual study design: Within-subject design, i.e. a cross-over study in which all participants try the devices consecutively
Participants	Country: USA Number randomised: 37 participants admitted to the Central Blind Rehabilitation Center. Age: 50 or more. Sex: not reported. Inclusion criteria: 50 or older, diagnosis of post-disciform stage AMD or ocular histoplasmosis. Exclusion criteria: eye pathologies which would affect study results by compromisingvisual function
Interventions	Before allocation all participants were trained by a visual skills instructor to use his or her best retinal viewing area. Modifications of standard techniques were used, including stand with the bar, the clock method of distance training, the fixation and reading techniques. Participant progress in eccentric viewing training was monitored with the Pepper Visual Skills for Reading Test. Treatments: 3 types of commonly-used magnifiers: CCTV Illuminated Stand magnifier in conjunction with a bifocal or reading prescription to compensate for accommodative demand; Spectacle reading lenses: either prism half eyes or microscopes. The magnification used for each device was the lowest that enabled the participant to consistently read excerpts from the Readers Digest using the preferred level of illumination and a reading stand. Prior to testing each participant had a 1-hour training/practice session under the supervision of a visual skills instructor from the Central Blind Rehabilitation Center teaching staff
Outcomes	Silent reading speed recorded in words per minute; reading comprehension tested at the end of the article using 5 general questions graded from 0 - 5. Testing was considered invalid if the score was less than 4; reading duration measured in minutes and defined as the time the participant could read without visual discomfort
Notes
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quasi-randomised study: the order of presentation of the devices was rotated (counterbalanced) for consecutive participants; even so, selection bias should be avoided since all participants used all devices (crossover nature of the study design)
Allocation concealment (selection bias)	Low risk	Order of randomisation can be foreseen because rotation was used; despite this, selection bias should be low since all participants used all devices (cross-over study design)
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow-up or exclusion after randomisation reported
Selective reporting (reporting bias)	Low risk	No protocol available, but primary outcome reported
Period effect	Low risk	Participants with disciform neovascular maculopathy were included who are expected to have stable vision during the study period
Carry-over effect and period-by-treatment interaction	Unclear risk	No details reported
Other bias	Low risk	No other bias identified

Methods	Within-subject study with random assignment of the first device used
Participants	2 groups of 15 veteran participants with age-related or juvenile macular degeneration or diabetic retinopathy, visual acuity 20/50 or less in the better eye
Interventions	Hybrid-diffractive spectacle magnifier compared with a refractive spectacle magnifier and an aplanatic spectacle magnifier (2 separate experiments)
Outcomes	MNREAD reading speed, reading acuity and critical print size. Pepper Visual skills for Reading Test. Morgan Low Vision reading Comprehensioon Assessment. Self-report of satisfaction with reading using a visual analogue scale
Notes
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random presentation of first device, but sequence generation method not described; even so, selection bias should be low since all participants used all devices (cross-over study design)
Allocation concealment (selection bias)	Low risk	Unclear if order of randomisation could be foreseen since no detail given; despite this, selection bias should be low since all participants used all devices (cross-over study design)
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow-up or exclusion after randomisation reported
Selective reporting (reporting bias)	Low risk	No protocol available, but primary outcome reported
Period effect	Unclear risk	No details reported
Carry-over effect and period-by-treatment interaction	Unclear risk	No details reported
Other bias	Low risk	No other bias identified

Study	Reason for exclusion
Blaskey 1990	Assessment of Irlen filters in people with reading difficulty not due to low vision
Bonatti 2008	Stand magnifier compared to hand magnifier regarding subjective preference, but reading speed or reading acuity data not available
Cheong 2005	Large-print reading training effect and not LVA effect studied
Cheong 2009	Reading performance of 29 participants with AMD assessed using their habitual stand magnifier with and without a temporary line guide attached; no comparison of different LVAs
Cohen 1991	LVAs compared in normal observers
Culham 2009	The study aims to elicit the users' responses to 4 electronic HMDs and to correlate users' opinion with performance, but no reading speed or acuity data for each device are provided
Goodrich 1977	Participants assigned to 2 groups but no randomisation used (information obtained by the first author)
Goodrich 2004	Within-subject or cross-over study but all participants underwent training and testing with the 3 devices in the same order
Jacobs 1990	Evaluated whether the colour of the screen altered performance of CCTV
Kuyk 1990	Comparison of motorised and manual focus Keplerian telescopes, but target spotting and not reading performance assessed
Lawton 1989	Before-and-after study on compensation filters boosting the amplitudes of the intermediate spatial frequencies more than the amplitude of the lower spatial frequencies. No control group
LOVIT 2008	Multicentre randomised study comparing the effectiveness of a low-vision rehabilitation programme with control (waiting list); outcome measure was change in participants' visual reading ability estimated from participant responses to the Veterans Affairs Low-Vision Visual Functioning Questionnaire (LV VFQ-48) reading items completed at baseline compared with 4 months after enrolment for the treatment and control groups. No comparison of different reading aids
Margrain 2000	No comparisons between LVAs
Parodi 2004	RCT including 28 participants comparing the effect of prisms (5 to 7 prismatic dioptres) in the better eye versus control. Excluded because the aim was to improve visual acuity
Rees 2006	Comparison of low-cost and high-cost hand-held magnifiers, but no comparison of different LVAs
Reeves 2004	The effectiveness of 3 models of low-vision rehabilitation for people with AMD compared rather than the efficacy of specific types of LVAs
Rohrschneider 1998	Assessed reading speed in CCTV with different image refresh rates (50, 60 and 70 Hz of frequency)
Rosenberg 1989	Quasi-randomised study comparing prismatic correction in 19 participants versus 11 controls. Excluded because the aim of the study was to improve visual acuity not reading acuity
Rossi 1990	Effect on walking and transfer assessed in stroke patients with hemianopsia or visual neglect using Fresnel prisms vs control. No reading speed data
Scott 2002	Evaluation of performance in icon identification tasks while the screen features of the graphical user interface were varied
Wolffshon 2002	Coloured lenses compared with no filter in 10 AMD people and 5 healthy controls, but reading speed not assessed

Methods	Quote: “Twenty-nine adults (distance visual acuity 20/80-20/320) from the Vision Rehabilitation Center read short paragraphs (41-44 words) using three 10X devices (a portable electronic magnification system (EMS), a hand held magnifier (MAG) and table top CCTV). Subjects read three font sizes (18, 12, and 8 pt, san serif) with each device. We defined a weighted words per minute reading rate from the time taken to read and approximate number of words read from each paragraph. We also recorded age (19-91), diagnosis (41% ARMD) and previous use of each device.”
Participants	29 adults
Interventions	A portable electronic magnification system (EMS), a hand held magnifier (MAG) and table top CCTV
Outcomes	Quote: “The group as a whole read faster with the CCTV, then magnifier, then portable EMS (P<0.0001). To our surprise, with each device, reading was slowest with 18 pt and fastest with 8 pt. There was no effect of familiarity with device. For subjects with ARMD, again, reading was fastest with CCTV but there was no difference between MAG and EMS. Unlike the group as a whole, reading rate was the same for all font sizes except with CCTV, where reading was fastest with 8 pt type. Conclusions: The portable EMS provides no benefit for low vision patients. The increase in reading performance with decreasing font size may be due to increased field of view. Further research is required.”
Notes	ARVO abstract only

Methods	Quote: “In this study we explored the effect reading training and device type (optical aid closed circuit television (CCTV)) on reading performance of individuals with central field loss. While a central field loss reduces reading performance, rehabilitation can restore function, but the question of how much rehabilitative training is necessary to optimize reading has not been addressed. Reading performance with low vision aids has similarly been shown to be effective, but the value of optics aids versus CCTV has not been extensively explored. METHOD: Fifty subjects with central field loss who participated in the rehabilitation program of the Western Blind Rehabilitation Center volunteered to participate in the stud; which used a randomized, counter-balances design. All subjects received comprehensive optometric examinations, were prescribed an optimum near vision optical aid and CCTV. The training group received ten days of instructor training with their optical aid and fifteen days of instructor training with their CCTV. The other group received five days of instructor training with the optical aid followed by five days of independent practice and seven days of training with the CCTV and eight days of independent practice. The variables of acuity, contrast sensitivity, reading speed and reading duration were measured.”
Participants	50 subjects with central loss
Interventions	Optimum near vision optical aid and CCTV
Outcomes Notes	Quote: “Short term instructor training combined with independent practice was as effective in optimizing reading speed and duration as was the longer term instructor training. CCTVs provided greater reading speed and duration than did optical aids. Reading performance with an optical aid was only moderately correlated with reading performance with a CCTV. CONCLUSION. Instructor training combined with independent practice is an effective method of rehabilitating reading skills. CCTVs offer advantages in terms of reading speed and duration. Reading training is a variable which, if taken into account, can improve both low vision clinical practice and research”American Academy of Optometry abstract only

Methods	Quote: “Reading aids are arguably the most frequently prescribed low vision device, yet there is little comparative information on the performance to be expected for different low vision devices prescribed for patients having different characteristics. PURPOSE. This study sought to provide comparative information for clinicians to assist in prescribing low vision reading devices, and for patients in selecting which device will best meet their needs in relation to its cost. METHOD. Subjects were 133 patients (mean age = 68.5 yrs) of the Western Blind Rehabilitation Center. Subjects were assigned to one of three groups based upon field loss: central (N = 90); peripheral (N = 28); or mixed central and peripheral field loss (N = 15). The study used a within subjects, counterbalanced design with all subjects trained in reading with an optical aid (primarily stand magnifiers or microscopic lenses) and CCTV. Reading speeds and durations were recorded.”
Participants	132 low-vision participants
Interventions	Optical aid (primarily stand magnifiers or microscopic lenses) and CCTV
Outcomes	Quote: “Central loss subjects read 20% faster and 34% longer with the CCTV than their best optical aid. Peripheral loss subjects read only 12% faster and 23% longer with CCTV than their best optical aid, and mixed loss subjects read only 9% faster and 34% longer. CONCLUSIONS. CCTVs, as a low vision reading device, provided all subjects in this study with an average of 23% to 34% longer reading durations. Reading speeds averaged between 9% and 20% greater. Central loss subjects appear to gain the greatest benefit from CCTV, while mixed and peripheral loss subjects gain a greater reading duration with the CCTV. The relative benefits of devices for each patient group will be discussed in the context of information that may assist the clinician in prescribing low vision reading devices. Prescribing information should encompass the patient s reading needs and the cost of the devices, as well as, information about the performance patient's can expect from the device.”
Notes	American Academy of Optometry abstract only

Methods	Quote: “Clinicians frequently prescribe reading devices for low vision patients having a central field loss, however there is an absence of critical types of information upon which to base this decision. In particular, there is a lack of information relating to the reading speed and duration to be expected from different types of low vision devices. PURPOSE. This study sought to provide comparative information for clinicians to use to assist clinicians in prescribing and patients in selecting the most cost-effective device. METHOD. The study compared optical aids with two types of CCTVs that differ in two important characteristics: price and whether the camera was stand mounted with an X-Y table or whether the camera was manually scanned. A within subjects design was chosen and we used measures of reading speed and duration as the performance measures. The 22 central field loss subjects indicated their preferences in response to seven forced choice or open-ended questions.”
Participants	22 central field loss participants
Interventions	optical aids and 2 types of CCTVs
Outcomes	Quote: “Subject reading speed and duration were significantly greater with the CCTV systems than with optical aids, however no significant differences were found between the two types of CCTVs. Patients expressed clear preference for one versus the other type of CCTV, with over-all preference for the standmounted system. When considering the price differential between types of CCTVs patient preferences were equally divided. CONCLUSIONS. Clinicians can expect significant reading performance differences between optical aids and CCTVs. Patients, given the opportunity to choose, will factor features, performance, and price information into the selection of low vision reading device(s).”
Notes

Methods	Quote: “Low power lasers have been used for purposes ranging from scanning laser ophthalmoscopes to heads-up displays for aircraft pilots. In this study we have begun a formal examination of one possible application as a reading display for low vision patients. The prototype device, called Nomad, is a monocular, head-mounted display that uses a red laser to display text onto the retina. A CCTV camera and XY table provided input. METHODS: Twenty subjects read with the prescribed optical device, CCTV, and Nomad. Data was collected on subject visual acuity, pathology, contrast sensitivity, duration of visual disability, and reading speed and reading duration with each device. In addition subjective impressions of the Nomad were gathered using both forced choice and open-ended questions.”
Participants	20 low vision participants
Interventions	Prescribed optical device, CCTV, and Nomad
Outcomes	“Subject reading speeds with the Nomad were faster than optical devices, but slower than CCTV. Reading durations with the Nomad were similar to that with CCTV; both of which were about 3X longer than optical devices. Subjective data indicated that subjects would prefer another color, or full-color laser for the Nomad and would like a more comfortable head-mount. Most subjects preferred the brightness and sharpness of the Nomad display to the displays of the optical devices and CCTVs. The brightness and high contrast may allow patients with extremely low vision to maintain, the ability to read visually even when conventional devices are no longer effective. CONCLUSIONS: The Nomad is a prototype display with potential as both a distance and near vision aid. At present it is a useful research tool to begin examining the potential benefits of new visual display technology. We will discuss our findings in relation to this potential.”
Notes	American Academy of Optometry abstract only

PERMALINK

Reading aids for adults with low vision

Gianni Virgili

Ruthy Acosta

Lori L Grover

Sharon A Bentley

Giovanni Giacomelli

Abstract

Background

Objectives

Search methods

Selection criteria

Data collection and analysis

Main results

Authors' conclusions

Background

Description of the condition

Description of the intervention

How the intervention might work

Why it is important to do this review

Objectives

Methods

Criteria for considering studies for this review

Types of studies

Types of participants

Types of interventions

Types of outcome measures

Primary outcomes

Secondary outcomes

Search methods for identification of studies

Electronic searches

Searching other resources

Data collection and analysis

Selection of studies

Data extraction and management

Assessment of risk of bias in included studies

Measures of treatment effect

Methods for future updates to this review

Unit of analysis issues

Dealing with missing data

Assessment of heterogeneity

Assessment of reporting biases

Data synthesis

Subgroup analysis and investigation of heterogeneity

Sensitivity analysis

Results

Description of studies

Results of the search

Figure 1.

Included studies

Figure 2.

Table 1. Description of outcomes in studies.

Design

Participants

Interventions

Outcome measures

Reading speed (primary outcome in this review)

Reading acuity

Quality of life

Reading duration

Preference for each device

Outcomes not used in this review

Excluded studies

Risk of bias in included studies

Allocation

Blinding

Incomplete outcome data

Selective reporting

Other potential sources of bias

Period effect: stability of disease during cross-over phases

Carry-over effect and period-by-treatment interaction: the potential risk of learning effect or fatigue during repeated testing

Effects of interventions

Electronic versus optical devices

Reading speed

Figure 3.

Reading duration

Comparisons between electronic devices

Stand-mounted CCTV versus head-mounted electronic device

Reading speed

Figure 4.

Methods	Within-subject study (2 low-vision aids tested on the same participant); order of presentation randomised (coin toss, as notified by the authors)
Participants	13 low-vision persons participated in the study. Their ages ranged from 57 - 82 years, average 70 years. Their best corrected visual acuity ranged from 0.01 - 0.3, average 0.04. They were asked to read characters with these 2 devices for 20 seconds text of decreasing print size
Interventions	A hand-held retinal projection system was compared with a face-mounted video display using a CCTV system
Outcomes	Reading speed, critical print size
Notes	Article in Japanese; authors have been contacted to collect data

Methods	Quote: “Portability and ease of text and spot reading is a challenge for low vision patients needing high levels of magnification. ‘Powervision,’ a new, head-mounted electronic magnification system, offers portable high magnification for reading. This pilot study compared the speed and accuracy of text and spot reading by low vision patients using ‘Powervision’ (P), traditional CCTV (C) and a comparable hand held magnifier (H). METHODS. Twenty patients from the Vision Rehabilitation Center of the Mass. Eye and Ear Infirmary best corrected to < or = 20/80, could read English, and consented to participate were included. Patients were scored on time and accuracy of reading three short paragraphs of text (8, 12, 18 pt print) and spot reading of a hospital bill. Patients reported ease of reading with each of the three devices.”
Participants	20 low-vision participants
Interventions	Powervision, traditional CCTV and a comparable hand held magnifier
Outcomes	Quote: “Ages ranged 22-92 (mean 58.3), with acuities of 20/80-20/800 (mean 20/267), and primary diagnoses of ARMD (23%) and other etiologies of visual loss. Text reading mean scores (360s maximum) were P: 313s, C: 180s, H: 248s, and accuracy (12.0=whole paragraph correct, 0=could not read) was P: 8.4, C: 11.3, H: 8.9. Spot reading mean times were P: 95s, C: 60s, H: 83s and accuracy (4.0= all correct, 8.0= all incorrect) measured P: 5.4, C: 4. 2, H: 5.1. Mean patient reports of ease of use (1=Very Easy, 5=Very Difficult) were P: 3.5, C: 1.9, H: 3.1 for text reading and P: 3.6, C: 1.7, H: 2.8 for spot reading. DISCUSSION. In this pilot population, despite its portability, Powervision scored less well on speed and accuracy of spot and test reading and for patient report of ease of use. Planned redesign and training in use may improve patient performance.”
Notes	ARVO abstract only

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Reading speed (words per minute)	3		Mean difference (Fixed, 95% CI)	3.13 [-3.47, 9.73]
2 Reading acuity (logMAR)	1		Mean difference (Fixed, 95% CI)	Totals not selected

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Reading speed (words per minute)	2		Mean difference (Fixed, 95% CI)	-9.54 [-19.36, 0.27]
2 Reading duration in minutes	1		Mean difference (Fixed, 95% CI)	Totals not selected