Managing presbyopia

SPEAKER: By the end of this presentation, you should be able to define presbyopia and describe its epidemiology and explore considerations for service delivery at the community level. Presbyopia is caused by age-related and progressive loss of elasticity in the crystalline lens in the eye. This diminishes people’s ability to focus on near objects and makes it increasingly difficult to read and write as well as carry out everyday tasks, such as sewing, sorting rice, cooking, or weeding, for example. People try to compensate for the problem by moving objects to arm’s length, but this has a limited effect. The global prevalence of refractive error as reported by the World Health Organisation does not include presbyopia.

Definitions of presbyopia– in functional presbyopia, significant optical correction, at least plus 1 dioptre, must be added to presenting distance refractive correction to achieve a near visual acuity improvement of either more than one line or so that N8 print can be read. N8 print is the same size as newsprint. Objective presbyopia is defined as needing significant optical correction, or greater than plus 1 dioptre, added to best corrected distance vision to improve near vision to N8 print. It’s important to remember the difference between these two definitions when you review epidemiological data, because people with uncorrected myopia do not develop functional presbyopia.

There have been a limited number of population-based studies in presbyopia. It was estimated that, globally, there were 517 million people without adequate correction for functional presbyopia in 2005. Some of these people would have had minimal correction requirements, and the estimate of those that are likely to experience significant difficulties with near work was about 410 million. Of these people, 94% lived in low- and middle-income countries. Projections indicate that urgent service provision is required in order to manage the projected need for presbyopic correction in the future. We have learned, from the limited studies in this area, that a higher prevalence of disabling presbyopia is seen in women compared to men.

People with secondary or higher education and urban populations also show higher prevalences. Interestingly, it has also been noted that people in hotter climates and in Asia and Africa tend to have a higher prevalence of disabling presbyopia and earlier onset of near-vision difficulties. Nearly half of Asian and African people aged over 30 experience disabling presbyopia compared to Caucasian people who begin to experience difficulties by the age of 45.

Challenges– presbyopia remains one of the most common refractive conditions for seeking treatment. Spectacle correction is not widely available in low- and middle-income countries. Barriers to uptake of services need to be locally understood. And presbyopia affects the working age group and their quality of life, and this can have an economic impact.

Service provision for presbyopia begins with estimating the need. Local studies can be used to estimate the need in a population. It is also reasonable to assume that 90% of people over the age of 45 will need spectacles for near correction, reading glasses. If some services are already in place, then an estimate of the met need can be obtained by carrying out a survey of people aged over 45, using a rapid assessment method called RARE. RARE stands for Rapid Assessment for Refractive Error. Coverage, or the extent to which people in the community who need near correction are actually receiving it, can then be calculated by dividing the met need by the estimated need and multiplying by 100 to give a percentage.

If coverage is found to be low, it is important to understand local barriers around awareness, access, affordability, and willingness to pay. Patient satisfaction rate and acceptance rates are usually very high with presbyopic spectacle correction.

Patients can be provided with different options for lenses. Single vision ready-made lenses are commonly used for lens powers of between plus 1 to plus 3. They are less expensive. But the patient experiences some inconvenience with distance vision, and they have to remove their glasses frequently. Bifocal or multifocal lenses are useful when added to a distance correction and the patient can use their spectacles for distance and near vision. These spectacles are more expensive, and it takes longer for the patient to adjust to them. These options must be considered when planning for service provision in the community.

Models of service provision for presbyopia vary within health systems. But primary health care, static, and outreach services should be planned in an integrated way to improve access in the community. At the community level, training for dispensing ready-made presbyopic spectacles should be considered through primary health care workers or pharmacists. Outreach screening and dispensing camps can also be used as a strategic service to reach adults over the age of 45. Finally, static units can be used to provide access to ready-mades and also patient-specific multifocals, which require more equipment and skills.

In conclusion, the magnitude of uncorrected disabling presbyopia has been estimated at 410 million people, with an increase to 563 million by 2020. 94% of the unmet presbyopic need is in low- and middle-income countries. 90% of people with presbyopia are aged over 45. Presbyopic correction lenses are available as ready-mades or as multifocal spectacles. Their use should be planned with local needs in mind. Services to improve access, availability, and affordability of presbyopic correction should be planned at the local level. And finally, primary health care, static, and outreach services should be integrated.