Presbyopia

Reading glasses. Ewelina Karmazyn / EyeEm

Many of us are lucky enough to not require eyeglasses for much of our early life. Then suddenly, at around the age of 40, we start to experience focusing problems when we try to read. It feels like our near vision progressively gets worse and worse. Many people attribute it to simply getting old. In the beginning it feels like our near vision focusing is delayed or slower to occur. Our eyes may feel tired and we may get headaches when we try to read for long periods of time.

Nowadays, people may find that they have to hold their cell phone or other digital device a little farther away to make it clear. As the years progress after age forty, it may seem like everything within arms-length becomes very blurry. This is called presbyopia.

Presbyopia Is Normal

As I always tell my patients, “presbyopia affects the very best of us.” This syndrome is referred to as the “over 40 vision syndrome.” Yes, it is linked to age, but one shouldn’t feel that they are simply losing their eyesight. Presbyopia is a normal process. Hundreds of years ago, the average lifespan was nearly 40. As a result, presbyopia never became a problem. As our average lifespan had increased to nearly 80 years of age, presbyopia has become a very real problem that affects our daily lives.

Physical Changes

The cornea, the clear, dome-like structure on the front part of our eye, is responsible for roughly 75% of the way light focuses onto our retina so that we can see images sharply.

However, inside our eye is the crystalline lens, located right behind the iris, the colored part of our eye. The crystalline lens looks just like a camera lens and is responsible for about 25% of the focusing power of the eye. It allows us to make small, quick, dynamic changes to our focusing ability as we look from distance to near and all distances in between.

It functions much like the auto-focus system in cameras. Around the lens is a muscle called the ciliary muscle. This muscle contracts and relaxes, allowing the lens to stretch out to become thinner or shrink to become fatter in the middle. These contractions allow the lens to change shape and cause a total power change of the eye that can keep items in focus as we look at different things.  

As we age, changes also occur inside the lens that causes it to lose its flexibility. We also lose a little bit of control over the ciliary body muscle and it becomes less elastic. Scientists and doctors feel that it is a combination of these two things that add up and cause us to develop presbyopia.  

A Need for Glasses

Presbyopia progresses slowly and causes significant changes in our near and intermediate vision from age 40 to about 60. This means that we may notice changes around 40 and every couple of years, our near vision may seem worse. Because of these changes, your eye doctor may prescribe several different optical devices to allow you to have good, functional near vision.

These devices may be simple over-the-counter readers, prescription reading glasses, bifocals, trifocals or no-line, progressive lenses. Sometimes contact lenses may also be prescribed.

Many people put off visiting their eye doctors because they feel like they are “giving in” and it will “make my eyes become dependent or become worse if I wear glasses.” Although a doctor could potentially influence the development of a human eye by prescribing devices below the age of 7, in adults, this will not happen. In adults, wearing corrective lenses will not make one’s vision weaker or make them become dependent on them. You might get used to clear vision so you realize how great a difference there is in corrected and uncorrected vision, but corrective lenses will simply help to focus your camera. The need to increase the power of the reading glasses every couple of years will occur with or without corrective lenses because the condition worsens naturally from age 40-60.  

Source: Benjamin, William J and Irvin M. Borish. Borish’s Clinical Refraction, second edition, Butterworth-Heinemann -Elsevier, 2006.

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