Magnifying reading devices or aids for adults with low vision

The number of people with low vision is increasing with the aging population. Magnifying optical and electronic aids are commonly prescribed to help people maintain the ability to read when their vision starts to fade, but still have some ability to see. We reviewed the evidence for the effect of reading aids on reading ability in people with low vision, with the aim of investigating whether there are differences in reading performance using conventional optical devices, such as hand-held or stand-based microscopic magnifiers, as compared to telescopic optical devices, or electronic devices such as stand-based, closed-circuit television and hand-held electronic magnifiers. The searches covered studies published until January 2013.

We found 10 studies (424 participants) comparing reading performance, mainly reading speed, in adults who are followed in low vision services. Most people were affected by macular degeneration, which causes loss of central vision and is often age-related.

Results from small studies of moderate or low quality were inconclusive, although they suggested faster reading speed with stand-based or hand-held electronic devices compared to stand-mounted or hand-held optical magnifiers. They also suggested that head-mounted electronic devices performed less well than optical magnifiers. The technology and versatility of electronic devices may have developed and improved since these trials were conducted between 1991 and 2005.

One study suggested that prism spectacles, or special glasses which are sometimes prescribed to try to help people with central visual loss to see objects outside their blind spot areas, were no more effective than conventional spectacles for people with age-related macular degeneration.

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.

Read the full 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 strategy: 

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.

Share/Save
Health topics: