It has long been recognised that magnification can help a visually impaired patient, or indeed any patient, undertake a variety of tasks, and therefore the chance to improve their quality of life and /or retain independence. In the past, many low vision practitioners tended to shy away from recommendation of electronic low vision aids (which historically tended to be grouped together as ‘CCTV’s), or to use the preferred terminology ‘electronic visual enhancement systems’ (EVES), often, but not exclusively, due to cost factors or the patient’s unfamiliarity with electronic and computer based devices.
Computers and electronic devices are now well established into everyday life, in schools, work environments and the home. Patients attending low vision clinics are increasingly computer literate, some having had prior years of experience perhaps in their current or previous jobs or indeed at home. Manufacturers of electronic low vision aids have also moved with the times, from supplying a limited range of aids to a now fairly extensive selection. A patient’s success with a low vision aid doesn’t just rest solely with acuity and other clinical measures, but is influenced by real-life considerations such as ease of use and cosmesis. Electronic devices may even be simpler to use than a standard optical magnifier due to familiarity, and additionally have the advantage of being perceived as more socially acceptable.
Who are they for?
Magnification in the optometric context should be regarded simply as a method of making the retinal image size larger, either by relative distance magnification, relative size magnification, angular magnification, projection/transverse/display magnification or a combination. EVES is essentially display magnification, displaying a larger image on a monitor, but can be enhanced by the inclusion of one of the other forms, for example moving towards the display or using a magnifier in combination.
Experienced low vision practitioners will be aware that the philosophy in the past was that electronic aids were only for the young and highly motivated visually impaired persons. Though this may obviously still hold some truth, encouragement of all age groups should now be the norm. Success with any low vision aid however, does still depend on a degree of motivation and similar criteria for suggesting an optical magnifier should therefore still be used if recommending an EVES.
As with traditional optical magnifiers, the assessment of visual acuity (VA), contrast sensitivity (CS) and visual fields (VF) remains essential. Common sense dictates the better these three factors are, the better the success with the aid will be. From experience, the author has found that EVES will only have limited success if the VA is worse than 1.20 and/or the contrast sensitivity worse that 22 per cent (0.60 Log CS), though some highly motivated patients may surprise you. Practitioners should not ignore the fact that there may be audio options with some devices that will enhance performance in the more significantly sight impaired.
Unlike traditional optical magnifiers, EVES are not available for funding via the NHS. There is statutory provision, following assessment, for those who are deemed eligible; ie for those in full time education, or those in employment via the ‘Access to Work’ scheme. For those in education, children are ‘statemented’ and receive a Statement for Special Educational Needs (SEN) which outlines the help they require which may include EVES. The Access to Work scheme provides practical support and financial help for those with visual impairment, and other disabilities. Some charities may help certain individuals, for example St Dunstan’s (Blind Veterans
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