At some stage, everyone starts to have trouble reading fine print. Whether the page is moved close to the eyes or held at arm’s length, the print is blurred and reading can become frustrating.
This loss of near vision happens to all of us and is quite normal. It begins for most of us in the early 40’s and this is called presbyopia. Fortunately there is a solution to this problem, wearing corrective spectacle lenses brings the sharpness again to fine print.
How your eyes work
Light rays enter through the pupil and are bent by the lens inside the eye so that they come to focus on the retina. The image formed is transmitted to the visual centres of the brain via the optic nerve.
The lens of the eye is responsible for about 30% of the eye’s total focusing power. As we age the lens becomes less flexible until it eventually loses the ability to take on the deeply curved shape required to focus on near objects.
Young eyes adjust easily
When we are young the lens inside the eye is quite flexible. This allows the lens to change shape to refocus the light onto the retina for near objects.
Near objects blur in presbyopia
When the lens loses flexiblility it will no longer bend light rays enough, therefore images formed on the retina by rays from near objects become blurred. This is because they are now focused at a point beyond the retina. The brain receives the blurry image that the retina sends, thus a focusing aid is needed.
Multifocal lenses in presbyopia
With the aid of multifocal lenses, the eye can receive a sharp picture for distance, intermediate and near. As presbyopia progresses, the eye is unable to focus on intermediate objects as well as for distance and near. In the past, bifocal lenses were used to combine a distance and near correction, however multifocals are now considered the lens of choice.
Advice on vision care
As your ability to focus declines you will need to have your eyes checked and your prescription changed every few years. Changes in vision due to presbyopia may continue to occur until around the age of 65 years.
Often factors other than age and visual conditions influence seeing problems. Certain visual tasks in our daily occupation may require specially designed lenses. Discuss your visual activities with your optometrist to ensure that you attain your full visual potential.
Apart from checking on the continuing condition of presbyopia, the eyes of people aged 40 years and over should be examined every two years to exclude the development of other eye health problems.