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.
To assess the effects of different visual reading aids for adults with low vision.
We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 12); MEDLINE Ovid; Embase Ovid; BIREME LILACS, OpenGrey, the ISRCTN registry; ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). The date of the search was 17 January 2018.
This review includes randomised and quasi-randomised trials that compared any device or aid used for reading to another device or aid in people aged 16 or over with low vision as defined by the study investigators. We did not compare low-vision aids with no low-vision aid since it is obviously not possible to measure reading speed, our primary outcome, in people that cannot read ordinary print. We considered reading aids that maximise the person's visual reading capacity, for example 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 and we did not consider rehabilitation strategies or complex low-vision interventions.
We used standard methods expected by Cochrane. At least two authors independently assessed trial quality and extracted data. The primary outcome of the review was reading speed in words per minute. Secondary outcomes included reading duration and acuity, ease and frequency of use, quality of life and adverse outcomes. We graded the certainty of the evidence using GRADE.
We included 11 small studies with a cross-over design (435 people overall), one study with two parallel arms (37 participants) and one study with three parallel arms (243 participants). These studies took place in the USA (7 studies), the UK (5 studies) and Canada (1 study). Age-related macular degeneration (AMD) was the most frequent cause of low vision, with 10 studies reporting 50% or more participants with the condition. Participants were aged 9 to 97 years in these studies, but most were older (the median average age across studies was 71 years). None of the studies were masked; otherwise we largely judged the studies to be at low risk of bias. All studies reported the primary outcome: results for reading speed. None of the studies measured or reported adverse outcomes.Reading speed may be higher with stand-mounted closed circuit television (CCTV) than with optical devices (stand or hand magnifiers) (low-certainty evidence, 2 studies, 92 participants). There was moderate-certainty evidence that reading duration was longer with the electronic devices and that they were easier to use. Similar results were seen for electronic devices with the camera mounted in a 'mouse'. Mixed results were seen for head-mounted devices with one study of 70 participants finding a mouse-based head-mounted device to be better than an optical device and another study of 20 participants finding optical devices better (low-certainty evidence). Low-certainty evidence from three studies (93 participants) suggested no important differences in reading speed, acuity or ease of use between stand-mounted and head-mounted electronic devices. Similarly, low-certainty evidence from one study of 100 participants suggested no important differences between a 9.7'' tablet computer and stand-mounted CCTV in reading speed, with imprecise estimates (other outcomes not reported).Low-certainty evidence showed little difference in reading speed in one study with 100 participants that added electronic portable devices to preferred optical devices. One parallel-arm study in 37 participants found low-certainty evidence of higher reading speed at one month if participants received a CCTV at the initial rehabilitation consultation instead of a standard low-vision aids prescription alone.A parallel-arm study including 243 participants with AMD found no important differences in reading speed, reading acuity and quality of life between prism spectacles and conventional spectacles. One study in 10 people with AMD found that reading speed with several overlay coloured filters was no better and possibly worse than with a clear filter (low-certainty evidence, other outcomes not reported).
There is insufficient evidence supporting the use of a specific type of electronic or optical device for the most common profiles of low-vision aid users. However, there is some evidence that stand-mounted electronic devices may improve reading speeds compared with optical devices. There is less evidence to support the use of head-mounted or portable electronic devices; however, the technology of electronic devices may have improved since the studies included in this review took place, and modern portable electronic devices have desirable properties such as flexible use of magnification. There is no good evidence to support the use of filters or prism spectacles. Future research should focus on assessing sustained long-term use of each device and the effect of different training programmes on its use, combined with investigation of which patient characteristics predict performance with different devices, including some of the more costly electronic devices.