Editorials

Minimising the impact of visual impairment

Low vision aids are a simple way of alleviating impairment 

Visual impairment is responsible for much individual suffering and economic hardship. Magnifying devices and other types of low vision aid can significantly reduce the degree of handicap associated with impaired vision. Two thirds of the people who would benefit from a low vision aid (about 600 000 people in the United Kingdom), however, do not possess one.¹ What are the reasons for this disturbing situation?

Currently about 316 000 people are registered as blind or partially sighted. However, the registers underestimate the number of people with low vision by a factor of three,² so almost 1 000 000 people in the United Kingdom have untreatable low vision. Community based surveys support this estimate and have shown that around 20% of those aged 75 and over have visual acuity less than 6/12.³ With the advent of annual screening for patients over 75 and the high prevalence of visual impairment, general practitioners are becoming increasingly familiar with low vision and its associated problems such as depression and falls. ^{4 5}

Demographic trends indicate that the situation is likely to get worse because the causes of low vision are predominantly age related. Unfortunately, medical intervention is unlikely to offer much help. No treatment currently exists for age related maculopathy, the primary cause of visual impairment in the United Kingdom. Furthermore, although continuing advances in the management of conditions such as glaucoma and diabetes are likely to reduce the degree of visual impairment associated with these conditions, the overall number of people with impaired sight may not diminish because the benefits of improved management are likely to be offset by the general trend toward increased life expectancy.

In the absence of a cure for blindness, rehabilitation is of paramount importance. The most effective way to reduce the degree of handicap associated with visual impairment is by providing low vision aids as part of a comprehensive low vision service.¹ When dispensed appropriately these simple magnifying devices enhance residual vision and often permit people with impaired sight to perform daily tasks such as reading. Regrettably, evidence based on observational studies and expert opinion collated by the Partially Sighted Society suggests that many people are not benefiting from this simple form of management.¹ The greatest consequence of this failure is that many old people require residential care because they can no longer live alone.¹ So why are low vision aids underused?

One reason might be that the benefits to be gained from the use of low vision aids are not widely recognised in the community. Yet the ability of these devices to alleviate the problems associated with visual impairment is well established, ^{1 6-8} and has been highlighed at Cardiff University's low vision clinic, which provides low vision services for the people of south Wales. Data collected over six months from 168 new referrals showed that, although only about 20% of those referred could read normal print when they first came to the clinic, this figure rose to almost 90% after provision of a suitable low vision aid and some training (unpublished data). Rarely can medical intervention be so effective. The improvement in reading performance addresses the primary complaint of people with age related maculopathy, and it is perhaps for this reason that more than 80% of people report a benefit from attending low vision clinics.⁶ Other reasons why people with impaired vision do not benefit from a low vision assessment include the fact that some may fail to recognise their degree of visual impairment or fear treatment, the stigma of blindness, and differences in ophthalmological referral criteria.

Nevertheless, low vision aids provide a simple and effective means of alleviating the problems associated with visual impairment. Greater provision of these inexpensive devices would greatly reduce both the social and economic impact of low vision.

Tom H Margrain, Head of low vision clinic and lecturer in optometry. 

Department of Optometry and Vision Sciences, Cardiff University, Cardiff CF1 3XF