Optical reading aids for children and young people with low vision

  • Protocol
  • Intervention

Authors


Abstract

This is the protocol for a review and there is no abstract. The objectives are as follows:

To assess the effect of optical low visual aids on reading in children and young people with low vision.

Background

Description of the condition

In 2004, the World Health Organization (WHO) reported that more than 161 million people worldwide were visually impaired, with 124 million classified as having low vision and 37 million classified as blind (defined as visual acuity less than 3/60 in the better-seeing eye (World Health Organization 2004). In children, prevalence of blindness varies from 0.3/1000 in high-income countries to over 1.0/1000 in low- and middle-income countries, equating to around 1.4 million blind children worldwide (Gilbert 2001; World Health Organization 2000). Low vision is about twice as common as childhood blindness, and might affect almost 3 million children worldwide (Gilbert 2008a; Gilbert 2008b).

The leading causes of low vision in children worldwide are retinal conditions, corneal scarring (vitamin A deficiency, measles, harmful traditional practices), globe anomalies, cataract, optic nerve anomalies, glaucoma, and central nervous system disorders (Gilbert 2001). A recent study in Nepal identified corneal disease as the leading cause of visual impairment followed by retinal disease and lens pathology. In 46% of children, however, the cause of visual loss could not be identified (Shrestha 2012). In high-income countries, brain damage sustained around the time of birth has become the leading cause of severe visual impairment (Bodeau-Livinec 2007; Mitry 2013; Rahi 2003). In England and Wales, the commonest conditions in children with impaired, but not severely impaired sight, are hereditary retinal conditions or congenital globe abnormalities (Mitry 2013).

In the UK, there are an estimated 25,000 children with vision impairment (VI) or severe vision impairment/blindness (SVI/BL) (Morris 2008). The cumulative incidence of SVI/BL by 16 years of age is 5.9, and that of VI around 7 per 10,000 live births (Bodeau-Livinec 2007; Rahi 2003). About 950 new cases of VI or SVI/BL are diagnosed each year (Bodeau-Livinec 2007).

Children are considered to have 'low vision' when the corrected visual acuity (VA) is between less than 6/18 and light perception in their better eye, or their visual field is less than 10 degrees from the point of fixation, but they use, or are potentially able to use, vision for the planning or execution, or both, of a task (World Health Organization 1992). There is an overlap with the definitions of VI and SVI/BL. The exact definition of childhood blindness is variable, but usually ranges between a best-corrected visual acuity of less than 6/60 to 3/60 in the better-seeing eye in a young person age under the age of 15 years (Gilbert 2001; World Health Organization 2004).

Visual impairment can result in developmental delay by reducing the range of experiences to which the child is exposed. Early assessment with provision and training of low vision aids (LVAs) is essential to improve functional vision and adaptation to visual impairment, so allowing most children to enter and remain in mainstream schools (Ducrey 1998; Massof 1998; Silver 1976a). In the UK, approximately 70% of children with VI are educated in mainstream schools where the use of LVAs to enable use of printed educational materials is essential (Morris 2008). In the developing world, access to enlarged print, or methods to enlarge text (i.e. computers or photocopiers) is more spartan, and magnifiers can be provided as a cheaper and more transportable option for children with low vision. Epidemiological studies in Pakistan have demonstrated that provision of basic magnification aids would permit at least 11% of children currently educated in schools for the blind to be moved to mainstream schooling (Sight Savers International 2003). This estimate, however, was based on a sample of 1000 children in schools for the blind and was subject to selection bias due to the small percentage of children with low vision currently being educated in special schools in low- and middle-income countries; the overall potential for improvement is significantly higher. In Nepal, optical intervention provided a significant improvement to the vision of 48.2% of children in schools for the blind, enabling those learning braille to learn to read visually, or visually in conjunction with braille (Gnyawali 2012). Despite this improvement however, only 34.8% of children were still using their LVA one year later. Damage or loss was the most common reason reported for cessation of use; however, inadequate instruction and inappropriate setting/lighting were also reported, both of which highlight the vital importance of maintenance of equipment - however basic - and instruction to enable its use (Gnyawali 2012).

Description of the intervention

LVAs can be defined as any device that enables a person with low vision to improve visual performance. LVAs can be classified into optical aids (magnifiers) and electronic 'assistive technologies' (AT). Non-optical aids (filters, tinted lenses and coloured overlays) are also sometimes used to enhance vision, but are less frequently used in children with visual impairment and will, therefore, not be included in this review.

Commonly used optical aids include:

  • magnifiers: hand and stand magnifiers, with and without illumination; in general, the higher the magnification the greater the restriction of visual field

  • high dioptric power reading glasses or near adds in bifocal glasses (above +4.00 DS and up to +20.00 DS)

  • distance telescopes or binoculars: a hand-held or spectacle-mounted lens system that provides magnification at greater distance

  • electronic magnification: the longest established form of electronic magnification uses closed-circuit television (CCTV).

Other devices increasingly used in educational settings include screen-magnifying and screen-reading software operated on computers (desktops, laptops, tablets). For the purpose of this review, we will exclude devices that include monitors to display enlarged text. The present review will focus on optical LVAs; assistive technologies including CCTV will be the topic of a second review. No review is planned on non-optical visual aids.

A different magnification strategy used in educational settings is the enlargement of hardcopy printed material. Decisions about which strategy is superior, i.e. LVAs or text modification, depends on the outcomes selected for evaluation. Any form of visual support, i.e. LVAs or enlarged print, can be expected to facilitate access to the educational curriculum and to enable a child to develop better reading and literacy skills. Compared with text enlargement, LVAs may have the additional advantage of providing children and young people with greater independence of access to printed material (Corn 2002; Douglas 2011). However, peer pressure and the fear of 'standing out' may reduce usage of LVAs by children and young people (Mason 1999).

Why it is important to do this review

Improving functional vision in children with vision impairment is important for enabling education and personal development, and for improving vision-related quality of life. The previously held belief that children with low vision should be treated as children with no vision may in the past have hampered the study and use of LVAs. The WHO identified and highlighted the provision, education and use of LVAs in children as a priority in managing children with vision impairment (World Health Organization 1992).

The use and benefit of LVAs in adults is well documented, although the need for further research into the comparative benefits of different types of visual aids was highlighted by a previous Cochrane review (Margrain 2000; Virgili 2013).  Multiple studies document the use and subjective benefit of LVAs in children (de Carvalho 1998; Haddad 2006; Haddad 2009), and training in the use of magnifiers has been shown to improve the beneficial effects of their use (Cox 2009). There appears to be, however, a lack of agreement and comparative data on relevant outcomes and benefits of LVAs in children and young people.

LVA users, i.e. children, their families and carers, as well as healthcare providers or commissioners, require high quality evidence to make informed choices about allocation of personal, institutional and public resources. Facilitating reading and literacy in children and young people not only optimises individuals' access to education and employment, but also benefits society. The rationale for this review is, therefore, to provide critical evaluation of information that is already available from high-quality trials, and to delineate a framework for future research and practice policies in low-income, middle-income, and high-income countries.

Objectives

To assess the effect of optical low visual aids on reading in children and young people with low vision.

Methods

Criteria for considering studies for this review

Types of studies

We will include randomised controlled trials (RCTs) and quasi-RCTs in this review. We will consider within-subject studies, in which the order of presentation of devices was randomised, as quasi-RCTs. Within-subject studies are similar in design to conventional cross-over studies, but instead of offering interventions sequentially, LVA studies frequently offer these simultaneously and measure outcomes sequentially, in the same session.

Non-randomised studies may be included in the discussion, but will be excluded from any meta-analysis.

Types of participants

We will include trials involving children between the ages of five and 16 years with low vision as defined by, or equivalent to, the WHO 1992 definition (World Health Organization 1992):

“A person with low vision is one who has impairment of visual functioning even after treatment and/or standard refractive correction, and has a visual acuity of less than 6/18 to light perception, or a visual field of less than 10° from the point of fixation, but who uses, or is potentially able to use, vision for the planning and/or execution of a task”.

We will exclude children of pre-school age, as young children tend to hold objects close to their faces to achieve magnification, and LVAs are not usually prescribed for this age group. When LVAs are issued to children under the age of five years, the aim is to introduce children to the concept of magnifying devices in a playful manner, and not actually to improve access to visual information.

Types of interventions

We plan to include studies that assess optical visual aids. These will include non-electronic magnifiers of all types. We will not include CCTV, which, although it magnifies, is an electronic device. A separate Cochrane review will explore the effects of assistive technologies in the same population. The motivation for splitting the topic into two reviews has its basis in the different objectives of these technologies. Optical aids are prescribed to facilitate reading and access to printed material by providing magnification. Electronic assistive technologies have a broader aim: facilitating access to education, but also social media and real-time information available via the internet, for example maps/directions, educational or leisure activities offered in the vicinity etc. As such, a comparison of optical aids with assistive technologies would be difficult, as trial outcomes would be limited to the smallest common denominator, i.e. reading-related outcomes. We will include studies where both mediums are used, however, if it is possible to isolate the data relating to the use of optical aids alone.

We will compare use of optical aids with standard practice, which consists of standard refractive correction including any required near add up to +4.00 DS in aphakic (lacking a lens) or pseudophakic patients. We will also include studies that compare different types of optical aids with each other, and compare optical aids provided with, or without, instructions for use.

Types of outcome measures

Outcome measures for objective outcomes include near visual acuity, distance visual acuity, and reading accuracy, comprehension and speed (Binns 2012). A range of questionnaires is available to measure functional outcomes relating to activities of daily living (ADL), psychological status, and quality of life (both voice-related (VRQoL) and health-related (HRQoL)), such as the Manchester Low Vision Questionnaire (MLVQ) (Harper 1999), the Low Vision Quality of Life Questionnaire (LVQoL) (Wolffsohn 2000), the National Eye Institute Visual Function Questionnaire (NEI-VFQ) (Mangione 1998; Mangione 2001), and the Impact of Vision Impairment profile (IVI) (Hassell 2000; Weih 2002). Only a few tools have been developed and validated for use in children and young people, and even fewer have been developed with focus groups of children and young people. Examples include the Impact of Vision Impairment Profile for Children (IVI_C) (Cochrane 2011), the Cardiff Visual Ability Questionnaire for Children (CVAQL) to assess VRQoL (Khadka 2010), the Functional Vision Questionnaire for Children and Young People with Visual Impairment (FVQ CYP) (Tadic 2013), and the general health-related Pediatric Quality of Life Inventory (Varni 2001; Varni 2002).

Usage of LVAs is an additional important outcome measure, as it may reflect pragmatic and emotional difficulties with using devices. Peer pressure and the fear of 'standing out' may lead to optical aids being used infrequently or abandoned (Mason 1999). Usage of the LVA is likely to be a more specific outcome measure than VRQoL and HRQoL tools.

Whilst the main aim of LVAs is to magnify visual information, near visual acuity, reflecting successful enlargement of text, is of limited value as a main outcome measure. Reading speed may be the most appropriate primary outcome, as it evaluates the functional visual effect of the aid. Reading performance has been found to be one of the best predictors of patient-reported visual ability and VRQoL (Hazel 2000; McClure 2000). Reading is an important function in daily life. It is a standard outcome in studies monitoring conditions causing visual impairment and in clinical trials evaluating the effectiveness of interventions (Rubin 2013). Maximum reading speed may be the most commonly used outcome in assessing the effect of reading aids, and is the primary outcome explored in a Cochrane review on reading aids for adults with low vision (Virgili 2013). It is typically stable across a range of print sizes over 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 1995; Ahn 1995a; Bailey 2003). Using standardised reading charts such as those in the Minnesota Low-Vision Reading test (MNREAD), a plot of reading speed against font size (adjusted for reading distance and expressed in logMar) can be obtained (Legge 2007). Typically, reading speed also slows above a certain magnification due to the restricted field of view and a lack of a proportional increase in the size of saccades (fast movements of the eyes) (Dickinson 2000).

The use of different font sizes in various studies is a methodological problem for meta-analysis. The most recent update of the Cochrane review on reading aids for adults with low vision included only studies assessing reading speed "when reading ordinary print size", i.e. 10 to 14 points (Virgili 2013). However, there is no universal agreement on ordinary print size for children. Books for young readers frequently use a large font size, i.e. 14 points or larger. School textbooks frequently reduce font size as their target audience matures, but there are no standards, and no recommendations as to when 'standard adult font size' (usually 9 to 14 points) should be used.

The type of reading material also influences reading speed. Research studies often use standardised reading charts such as the MNREAD and, more recently, the International Reading Speed Texts (IReST). Repeated, standardised assessment of reading performance requires a collection of texts of similar difficulty. Whilst the MNREAD chart contains single short sentences, IReST consists of 10 paragraphs of texts (around 130 words each) and offers the advantage of a longer paragraph, which facilitates more accurate measurement of reading speed and judgement of fluency and mistakes (Trauzettel-Klosinski 2012). IReST has been evaluated in a cohort of normal sighted young adults and in patients with age-related macular degeneration, but has not been validated in children and young people.

In addition to reading performance, literacy outcomes such as reading accuracy and comprehension can give additional functional information. A measure of reading ability used in children with vision impairment is the Neale Analysis of Reading Ability (NARA), currently available in its second edition (NARA II) (Neale 1997). This is a comprehensive assessment of reading ability aimed for use with pupils aged 6 to 12 years, and is also recommended for use beyond the age of 12 years in children with sensory impairment. The test material consists of six paragraphs that increase in length from 26 to 140 words, and increase in difficulty.The test is designed to assess oral reading ability in terms of reading rate, accuracy and comprehension. Validation data are available for normally sighted individuals, and also for children and young people with visual impairment (Douglas 2002; Hill 2005). There are two parallel versions of the test, which permits the same child to be re-tested without remembering a previous test and thereby altering the score. The child’s scores are converted into reading ages for accuracy, comprehension and speed. Accuracy is determined by noting reading errors such as mispronunciations, substitutions, refusals, additions, omissions and reversals. Comprehension is measured by asking the child a number of set questions concerning the passage he/she has just read. Reading speed is measured by timing the passages read and converting this into words per minute over the total number of passages read. Results can be plotted as graphs comparing the performance of VI-students with normal-sighted age-matched peers (Douglas 2002; Hill 2005).

All literacy evaluations need to take into account that children are learning to read, i.e. are developing a skill. Children with low vision often read print more slowly and less accurately than normal, sighted peers (Douglas 2004; Gompel 2004). Comprehension may also be delayed; this may be linked to general delay in reading development (Douglas 2002). Other literacy tests used in educational settings, such as the National Foudation for Educational Research (NFER) and Access Reading Test (ART), include access features for children with low vision (enlarged print, braille, extended time), but no data from children with low vision are available.

Primary outcomes
  • Maximum reading speed in words per minute using MNREAD, IRest, NARA or NARA II

Secondary outcomes

Any of the following outcomes assessed using a standardised chart such as MNRead or IReST, or a standardised literacy test such as NARA.

  • Reading accuracy as errors per words read.

  • Reading comprehension as number of correctly answered set questions concerning the text read.

  • Reading acuity in logMar, defined as the smallest print that the child/young person can read without making significant errors.

  • Critical print size, defined as the smallest print that the child/young person can read with maximum speed.

  • Fatigue-free reading duration in minutes.

Secondary outcomes with different means of assessment (i.e. not standardised chart or literacy test).

  • Acceptance of the LVA, as reflected in usage (days per week, hours per day, at home and at school).

  • Independent learning, i.e. ability to access the curriculum independently, as assessed by questionnaires.

  • VRQoL, evaluated using any validated VRQoL scale for children.

  • HRQoL evaluated using any validated HRQoL scale for children.

  • Cost effectiveness.

  • Adverse outcomes, for example loss of motivation to use the device.

With regard to the timepoints of evaluation, general child development and, particularly, the development of reading and literacy skills will affect the effect size of interventions at given timepoints. One would expect an increase in reading speed with time as a younger child learns to read, regardless of LVA use, but using an aid may allow faster development of reading skills. On the other hand, a child’s ability may have improved to a degree over that period of time, just as his/her general development has progressed.

For this review, we will consider the following timepoints: Primary outcome: three and 12 months (+/- 3 months) after the intervention and relevant instructions, if any, have been issued, where three months is a proof of concept. Secondary outcomes: 12 months (+/- 3 months).
Ultimate outcomes such as educational attainment, as measured in educational progress, would be desirable, but due to the length of follow-up required, these are unlikely to be captured in research studies.

Search methods for identification of studies

Electronic searches

We will search the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Group Trials Register) (latest issue), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to present), EMBASE (January 1980 to present), the Health Technology Assessment Programme (HTA) (www.hta.ac.uk/), 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 will not use any date or language restrictions in the electronic search for trials.

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

Searching other resources

We will also use manual searching to check the references listed in retrieved articles. Manufacturers of LVAs will be contacted to request any information of which they are aware about studies or research regarding their products.

Data collection and analysis

Selection of studies

Independently, two review authors will assess titles and abstracts for eligibility. Studies will be divided into categories to 'definitely include', 'definitely exclude' and 'possibly include', and final judgements about inclusion/exclusion will be made by obtaining full text copies of the studies in the 'possibly include' category. Abstracts and, where necessary, full text articles will be translated into English before a final decision is made regarding inclusion/exclusion. Disagreements between the two review authors will be resolved by discussion or a designated third author, or both.

Data extraction and management

Independently, two authors will extract data using a data extraction form (see Appendix 8) developed in conjunction with the Cochrane Eyes and Vision Group using Chapter 7.3 of the Cochrane Handbook for Systematic Reviews of Interventions for guidance (Higgins 2011a). Data will be entered into Review Manager (RevMan) software by one author and independently reviewed and cross-checked by a second (Review Manager 2012).

When continuous data are available, we will extract data on the mean and standard deviation (SD) in each group. RevMan will calculate the mean difference and 95% confidence intervals (CI). When dealing with cross-over studies we will use the generic inverse variance method (Higgins 2011c).

Assessment of risk of bias in included studies

Two authors will work independently to review the risk of bias of included studies using the Cochrane Collaboration's 'Risk of Bias' assessment tool, detailed in Chapter 8 of the Cochrane Handbook for Systematic Review of Interventions (Higgins 2011b), as guidance. The five main domains of the tool include:

Selection bias

Studies will be graded by review authors as 'high risk', 'low risk' or 'unclear risk' based on the method of randomisation (sequence generation) and allocation concealment. If an 'unclear risk' assessment is made, study authors will be contacted to provide further information to enable a more detailed risk assessment to be made.

Performance bias

Masking of participants will not be possible given the nature of the intervention in question. We will, therefore, not grade studies on the basis of masking alone. A judgement regarding performance bias will be made by the review authors, taking into consideration the instruction and education given to participants for each visual aid and the 'learning-effect' time allocated before the final assessment is made.

Attrition bias

Incomplete outcome data will be recorded and attempts will be made to contact the study authors in order to obtain complete data. A judgement of 'high risk', 'low risk' or 'unclear risk' of attrition bias will be made by review authors with regard to the completeness of the data and the handling of incomplete data in the studies.

Detection bias

Masking of study investigators and personnel will not be possible due to the nature of the intervention in question. Detection bias will occur if the allocated intervention, i.e. use of the optical aid is visible to the outcome assessor. One way of reducing this risk would be to record reading on audiotape, or as audiofile, and later to have masked evaluation by a masked observer. We will judge studies on use of masking strategies. Detection bias may, in turn, affect reporting, if assessors then chose to exclude some participants or type of devices based on performance, thereby introducing reporting bias.

Reporting bias

Where a study protocol is available, the review authors will compare the published protocol with the final outcomes reported to assess the risk of selective outcome reporting as 'high risk', 'low risk' or 'unclear risk'. Where no protocol is available, the full text article will be studied to make this judgement.

Other bias

The review authors will judge whether each study design is subject to any other risks for the introduction of bias that are not detailed above. In particular, we expect studies with within-subject design to be commonly used in assessing the benefit of LVA, as a previous Cochrane review found this to be the case in studies investigating the use of LVAs in adults (Virgili 2013). A particular problem with this design in paediatric studies is that by the time participants start using a second intervention they may have matured and acquired more skills, which may influence the effect size of the second intervention. Chapter 16 of the Cochrane Handbook for Systematic Reviews of Interventions recommends that when cross-over studies are evaluated reviewers should take into account whether the condition is chronic and stable, whether the intervention provides temporary relief and not permanent change, whether the outcome can be repeated in the second period if it occurs in the first, whether the effect of the first intervention lasts into the second treatment period, and whether trial length is sufficient to allow appropriate use of the intervention (Higgins 2011c).

Within-subject studies can provide randomisation by including independent sequence generation and allocation concealment. We will grade both sequence generation and allocation concealment as factors carrying a 'low risk' of bias in these studies (Virgili 2013). We will ask two questions to rate the quality of randomisation and allocation in this type of study: 1. Does knowledge of the first LVA selected affect recruitment into the trial, and 2. Does the order in which the LVAs are used affect the results?

For within-subject studies testing several devices within the same research session, knowledge of the first LVA should not affect recruitment. In such situations we will consider two additional items for question 2: 1) period effect, that is, whether the condition might change during subsequent phases of testing of each device; and 2) carry-over effect and period-by-treatment interaction, that is, whether the effect on performance of using a specific device affects the performance of the devices assessed afterwards (Virgili 2013).

Review authors will not be masked to any aspect of the study design and any disagreement will be settled by discussion or a third designated author, or both.

Measures of treatment effect

We will summarize results in a 'Summary of findings' table using relative and absolute measures of effect.

The primary outcome (reading speed) is a continuous variable, as are reading accuracy, comprehension, acuity, print size, duration, acceptance/usage. Validated VRQoL and HRQoL tools also deliver continuous scores.

Non-continuous variables will not be included in the meta-analysis. These may include data assessed by non-validated questionnaires, such as 'independent learning', and data such as 'cost-effectiveness' and 'adverse outcomes'.

Unit of analysis issues

Individual patients/children, rather than individual eyes will be used as the unit of randomisation, as the use of LVAs is most commonly binocular.

Although near and distance visual acuity is commonly measured for individual eyes in a clinical setting, reading speeds and educational assessments are routinely obtained with both eyes open. This allows a more functional assessment, based on the better seeing eye and excluding artefacts such as, for example, an increase in nystagmus amplitude by covering one eye. Studies that measure outcome in the better eye will be included.

As the main outcome is measured at the person level, we do not expect any unit of analysis issues.

Dealing with missing data

Study authors will be contacted to obtain missing data where necessary. Where not available, or forthcoming, the details of the missing data and the handling of this in the outcome reporting will be looked at and reported in detail.

Assessment of heterogeneity

We will examine the characteristics of the included studies to identify clinical, methodological and statistical heterogeneity. Methodological heterogeneity may arise from differences in interventions, masking, allocation concealment, outcomes and their measurement.

If sufficient studies are identified, we will use the I2 statistic with CIs along with inspection of forest plots (poor overlap of CIs) to assess heterogeneity as detailed in Chapter 9 of the Cochrane Handbook for Systematic Reviews of Interventions (Deeks 2011). The interpretation of this statistic will be in line with the guidance in the Handbook, where an I2 value of over 50% will be considered to represent 'substantial' (50% to 90%), or 'considerable' (75% to 100%) heterogeneity.

Assessment of reporting biases

Assessment of reporting bias will be carried out as detailed in the Assessment of risk of bias in included studies section above. If 10 or more studies are included in analysis, we will construct a funnel plot and examine it for asymmetry in order to assess reporting bias.

Data synthesis

Meta-analysis will be carried out if more than one RCT is identified and there is sufficient homogeneity in study design to yield a meaningful analysis. It will be conducted according to Chapter 9 of the Cochrane Handbook for Systematic Reviews of Interventions (Deeks 2011).

Since a within-subject design is common in research on the effectiveness of LVAs (Virgili 2013), these studies will be included if the devices are presented in randomised or quasi-randomised order. This study design leads to specific issues, such as within-subject correlation and multiplicity of testing. We will deal with these issues using methods suggested in Elbourne 2002 and in Chapter 16 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011c).

Subgroup analysis and investigation of heterogeneity

No subgroup analysis will be conducted.

Sensitivity analysis

Sensitivity analysis will be conducted to establish the effect of:

  • assumptions made when dealing with missing data;

  • excluding studies at 'high risk' of bias.

Acknowledgements

The Cochrane Eyes and Vision Group (CEVG) will create and execute the electronic search strategies. We wish to thank Gianfrancesco Villani and Catey Bunce for peer review comments on the protocol and Gianni Virgili, Jennifer Evans and Anupa Shah for general guidance on the protocol.

Richard Wormald (Co-ordinating Editor for CEVG) acknowledges financial support for his CEVG research sessions from the Department of Health through the award made by the National Institute for Health Research (NIHR) Biomedical Research Centre based at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health.

Appendices

Appendix 1. CENTRAL search strategy

#1 MeSH descriptor: [Vision, Low] explode all trees
#2 low near/2 vision*
#3 MeSH descriptor: [Visually Impaired Persons] explode all trees
#4 (vision* or visual*) near/2 impair*
#5 MeSH descriptor: [Blindness] explode all trees
#6 MeSH descriptor: [Hemianopsia] explode all trees
#7 hemianop*
#8 quadrantanop*
#9 amauros*
#10 (handicap* or disabil* or disabl*) near/3 (visual*)
#11 (handicap* or disabil* or disabl*) near/3 (vision)
#12 #1 or #2 or #3 or #4 or #5 or #6 or #7 or #8 or #9 or #10 or #11
#13 MeSH descriptor: [Sensory Aids] explode all trees
#14 MeSH descriptor: [Lenses] this term only
#15 MeSH descriptor: [Optics and Photonics] this term only
#16 MeSH descriptor: [Optical Devices] this term only
#17 "low vision aid"
#18 MeSH descriptor: [Reading] explode all trees
#19 (aid* or device* or instrument* or equipment or apparatus) near (read*)
#20 (aid* or device* or instrument* or equipment or apparatus) near (optic*)
#21 telescop* or magnifi* or binocular*
#22 #13 or #18 or #20 or #21
#23 MeSH descriptor: [Child] explode all trees
#24 MeSH descriptor: [Infant] explode all trees
#25 MeSH descriptor: [Adolescent] explode all trees
#26 MeSH descriptor: [Pediatrics] explode all trees
#27 boy* or girl* or child* or minor* or offspring or prepubescen* or pubescen*
#28 adolescen* or juvenile* or teen or teens or teenage* or youth or youths or underage
#29 paediatric* or pediatric*
#30 (primary or elementary or high or secondary) near/1 school*
#31 nurser* or kindergarten* or preschool* or pre school* or school*
#32 schoolchild* or schoolage or highschool* or daycare
#33 #23 or #24 or #25 or #26 or #27 or #28 or #29 or #30 or #31 or #32
#34 #12 and #22 and #33

Appendix 2. MEDLINE (OvidSP) search strategy

1. randomized controlled trial.pt.
2. (randomized or randomised).ab,ti.
3. placebo.ab,ti.
4. dt.fs.
5. randomly.ab,ti.
6. trial.ab,ti.
7. groups.ab,ti.
8. or/1-7
9. exp animals/
10. exp humans/
11. 9 not (9 and 10)
12. 8 not 11
13. exp vision low/
14. (low adj2 vision$).tw.
15. exp visually impaired persons/
16. ((visual$ or vision$) adj3 impair$).tw.
17. exp blindness/
18. exp hemianopsia/
19. hemianop$.tw.
20. exp quadrantanopsia/
21. quadrantanop$.tw.
22. amauros$.tw.
23. ((handicap$ or disabil$ or disabl$) adj3 vision$).tw.
24. ((handicap$ or disabil$ or disabl$) adj3 visual$).tw.
25. or/13-24
26. sensory aids/
27. Lenses/
28. "Optics and Photonics"/
29. Optical Devices/
30. "low vision aid$".tw.
31. exp reading/
32. ((aid$ or device$ or instrument$ or equipment or apparatus) adj3 read$).tw.
33. ((aid$ or device$ or instrument$ or equipment or apparatus) adj3 optic$).tw.
34. (telescop$ or magnifi$ or binocular$).tw.
35. or/26-34
36. exp child/
37. exp adolescent/
38. exp pediatrics/
39. (boy$ or girl$ or child$ or minor$ or offspring or prepubescen$ or pubescen$).tw.
40. (adolescen$ or juvenile$ or teen or teens or teenage$ or youth or youths or underage).tw.
41. (paediatric$ or pediatric$).tw.
42. ((primary or elementary or high or secondary) adj1 school$).tw.
43. (schoolchild$ or schoolage or highschool$ or daycare).tw.
44. or/36-43
45. 25 and 35 and 44
46. 12 and 45

The search filter for trials at the beginning of the MEDLINE strategy is from the published paper by Glanville et al (Glanville 2006).

Appendix 3. EMBASE (OvidSP) search strategy

1. exp randomized controlled trial/
2. exp randomization/
3. exp double blind procedure/
4. exp single blind procedure/
5. random$.tw.
6. or/1-5
7. (animal or animal experiment).sh.
8. human.sh.
9. 7 and 8
10. 7 not 9
11. 6 not 10
12. exp clinical trial/
13. (clin$ adj3 trial$).tw.
14. ((singl$ or doubl$ or trebl$ or tripl$) adj3 (blind$ or mask$)).tw.
15. exp placebo/
16. placebo$.tw.
17. random$.tw.
18. exp experimental design/
19. exp crossover procedure/
20. exp control group/
21. exp latin square design/
22. or/12-21
23. 22 not 10
24. 23 not 11
25. exp comparative study/
26. exp evaluation/
27. exp prospective study/
28. (control$ or prospectiv$ or volunteer$).tw.
29. or/25-28
30. 29 not 10
31. 30 not (11 or 23)
32. 11 or 24 or 31
33. exp visual disorder/
34. exp visual impairment/
35. exp blindness/
36. (low adj2 vision$).tw.
37. ((visual$ or vision$) adj3 impair$).tw.
38. exp hemianopia/
39. hemianop$.tw.
40. quadrantanop$.tw.
41. amauros$.tw.
42. ((handicap$ or disabil$ or disabl$) adj3 vision$).tw.
43. ((handicap$ or disabil$ or disabl$) adj3 visual$).tw.
44. or/33-43
45. exp visual aid/
46. exp general medical aids/
47. optical instrumentation/
48. exp reading/
49. ((aid$ or device$ or instrument$ or equipment or apparatus) adj3 read$).tw.
50. ((aid$ or device$ or instrument$ or equipment or apparatus) adj3 optic$).tw.
51. (telescop$ or magnifi$ or binocular$).tw.
52. or/45-51
53. exp child/
54. exp adolescent/
55. exp pediatrics/
56. (boy$ or girl$ or child$ or minor$ or offspring or prepubescen$ or pubescen$).tw.
57. (adolescen$ or juvenile$ or teen or teens or teenage$ or youth or youths or underage).tw.
58. (paediatric$ or pediatric$).tw.
59. ((primary or elementary or high or secondary) adj1 school$).tw.
60. (schoolchild$ or schoolage or highschool$ or daycare).tw.
61. or/53-60
62. 44 and 52 and 61
63. 32 and 62

Appendix 4. HTA Programme search strategy

low vsion

Appendix 5. metaRegister of Controlled Trials search strategy

reading aids AND low vision

Appendix 6. ClinicalTrials.gov search strategy

Reading Aids AND Low Vision

Appendix 7. ICTRP search strategy

Low Vision = Condition AND Reading Aids = Intervention

Appendix 8. Data extraction form

Review author 
Study ID 
Dates when study was conductedIf not available, comment "dates not available" 
Funding source(s) 
Declarations of interest by researchers 
Methods

Study design, e.g. parallel group randomized trial, cluster-randomized trial, controlled before and after study, within-subject

Duration

Within-subject design: method of intervention allocation

Participants

Total number, number in each group (sample size)

Comparability

Setting

Risk of biasAssessed using risk of bias tool (see Handbook)

Outcomes (as defined in study)

Please specify which

Primary outcome

  • Maximum reading speed in words per minute using MNREAD, IRest, NARA or NARA II

Secondary outcomes

  • Reading accuracy as errors per words read

  • Reading comprehension as number of correctly answered set questions concerning the text read

  • Reading acuity in logMar, defined as the smallest print that the child/young person can read without making significant errors

  • Critical print size, defined as the smallest print that the child/young person can read with maximum speed

  • Fatigue-free reading duration in minutes,

all assessed using a standardised chart such as MNRead or IReST or a standardised literacy test such as NARA.

  • Acceptance of the LVA, as reflected in usage (days per week, hours per day, at home and at school)

  • Independent learning, i.e. ability to independently access the curriculum, as assessed by questionnaires

  • VRQoL, evaluated using any validated VRQoL scale for children

  • HRQoL evaluated using any validated HRQoL scale for children

  • Cost effectiveness

  • Adverse outcomes, for example loss of motivation to use the device

Interventions compared

Intervention 1 =  Standard care (baseline refractive correction), or LVA (specify type)

Intervention 2 = LVA (specify type)

additional interventions: LVA - specify type

 PRIMARY OUTCOME:
Maximum reading speed
Intervention 1Intervention 2
Time pointTotal number of participantsMean Standard deviation*Total number of participantsMeanStandard deviation* 
 Baseline      
 Immediately after intervention issued      
3 months      
6 months      
12 months      
 Intervention 3Intervention 4
Time pointTotal number of participantsMeanStandard deviation*Total number of participantsMeanStandard deviation*
Baseline      
Immediately after intervention issued      
3 months      
6 months      
12 months      
 
 
SECONDARY OUTCOMES:
Copy table for each secondary outcome
Intervention 1Intervention 2
Time pointTotal number of participantsMeanStandard deviation*Total number of participantsMeanStandard deviation*
Baseline      
Immediately after intervention issued      
3 months      
6 months      
12 months      
 Intervention 3Intervention 4
Time pointTotal number of participantsMeanStandard deviation*Total number of participantsMeanStandard deviation*
Baseline      
Immediately after intervention issued      
3 months      
6 months      
12 months      
       
 

Contributions of authors

Lucy Barker: design and co-ordination of review and writing the protocol.
Annegret Dahlmann-Noor: guarantor of review; design of review and writing the protocol.
Gary Rubin, Rachel Thomas: design of review and writing the protocol.

Declarations of interest

None of the authors have any commercial or proprietary interests to declare.

Sources of support

Internal sources

  • National Institute for Health Research (NIHR) Biomedical Research Centre (BRC), UK.

    The research is supported by the NIHR BRC based at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.

External sources

  • No sources of support supplied

Ancillary