The ability of the eye to focus objects clearly at various distances is dependent on the flexibility of the eye’s crystalline lens. The closer an object is, the more lens flexure required. Lens flexibility gradually diminishes with age, so that by the time we reach our 40s we find ourselves pushing objects further away to help us see them more clearly. The condition is termed Presbyopia and is the most common cause of vision impairment globally (ultimately affecting everyone who lives beyond middle age). Presbyopia can be corrected with reading glasses, but more than half of those requiring near-vision spectacles globally cannot access them due to factors such as poverty, isolation, poor availability, poor access to eye health facilities and lack of awareness. Whilst far less common, ocular diseases which impair distance vision, (eg Cataract), would also impair near vision.
Average sub-regional rates of Near-Vision Impairment due to lack of reading glasses
Poor global recognition of near-vision impairment
Currently, near-vision impairment due to uncorrected Presbyopia is not classified as a visually impairing condition under the WHO International Statistical Classification of Diseases, Injuries and Causes of Death, 10th Edition (ICD-10). There is also relatively little in the literature on near-vision loss. The reasons are unclear. Perhaps it is considered a relatively trivial problem, one that can easily be overcome with spectacles in most cases and in places were spectacles are difficult to obtain, (e.g. in low-income settings) literacy and life expectancy are generally lower and hence there might be less need of correction. However, there is a growing body of research suggesting that near vision matters just as much to people, if not more, than distance vision regardless of their setting or circumstances.
Impact of Near-Vision Impairment
Studies in rural Africa have shown poor near vision leads to a significant decrement in quality of life . In these populations, spectacles are essential for a range of activities such as sorting grains, weeding, cooking, sewing and caring for children. One study conducted with an elderly Nigerian population (> 65 years) found that near-vision impairment had a broader impact on quality of life than distance-vision impairment since it affected more aspects of day-to-day life .
Evidence is proof
A study conducted in Australia found that reduced quality of life due to vision impairment was strongly correlated with the level of visual acuity reduction a person suffered, but sociodemographic or lifestyle factors did not appear to influence the findings. This study also found that quality-of-life reductions for near-vision impairment were equal to reductions due to distance-vision impairment .
Uncorrected Presbyopia also has an impact on employment, and hence is very costly for society in an economic sense .
The global burden of uncorrected Presbyopia, in terms of lost productivity, is estimated to be just over US$11 billion annually.
Global burden of near-vision impairment due to lack of reading glasses
|Age range of populations considered||Cost in lost productivity||% GDP|
|<50 Years||US$11.02 Billion||0.016|
|<65 Years||US$25.37 Billion||0.037|
Interventions aimed at alleviating near-vision impairment due to uncorrected Presbyopia are simple and extremely cost-effective . In settings with limited resources, ready-made spectacles are an effective and inexpensive means to deliver vision correction, but this is only part of the solution for effective intervention. There is a severe shortage of eye care providers in developing communities world-wide who have the expertise to deliver services. Providing training and education programmes suitable for the delivery of eye care services, as well as the infrastructure for training to be carried out, is imperative for effective intervention.
The prevalence of near-vision impairment due to uncorrected Presbyopia is around four times the prevalence of distance-vision impairment due to all causes combined.
Global prevalence of vision impairment
correctable with spectacles
correctable with spectacles
due to ocular disease
Studies in rural Africa have shown poor near vision leads to a significant decrement in quality of life. Spectacles are essential for a range of activities such as sorting grains, weeding and cooking.