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Presbyopia

What is Presbyopia?

Presbyopia stems from the Greek word that means 'old eyes'!

Generally, it is an ageing process affecting a person's ability to focus on objects nearby, impairing concentration and accuracy. The 'run-up' to Presbyopia starts in your early thirties and first affects your close viewing significantly once you are between 38 and 43 years old, statistically, where adjusting your focus to close work at your average working distance (40 cm) becomes more difficult. Some lucky individuals leading healthy lifestyles and having the correct genetic predisposition may experience it a couple of years later.

Where does Presbyopia happen?

Presbyopia affects the crystalline lens situated right behind the iris. (When you look at someone's pupil, you're looking at the front surface of the crystalline lens). This lens's function is to change shape and bring close objects into focus. This is known as 'Accommodation'.

The lens is connected by fine ligaments to a muscle surrounding it, called the Ciliary muscle. For the lens to change shape the muscle contracts, bringing the point of focus closer to the eye.

It is important to understand that it is mainly the lens that causes Presbyopia and not the muscles of the eye. With time the muscle does become weaker, but it is not the main contributor to Presbyopia. In a normal eye the Ciliary muscle is still capable of contraction after the crystalline lens has lost its flexibility!

Why does Presbyopia happen?

The lens is made up of various layers. As you get older, the number of these cellular layers escalates, increasing the lens's density and reducing its flexibility. The ciliary muscle must then work harder and harder to get the lens to assume the right shape, leading eventually to normal muscle fatigue.

Symptoms

The first symptoms are usually tiredness around the eyes, and head and neck aches. At first you may not ascribe it to an eye condition, but perhaps exhaustion or stress. These symptoms may seem worse at night when there is less light around causing occasionally blurry vision. You may also feel your arms are getting a bit short, because you can't hold the newspaper away far enough!

When you reach 43 years of age it is almost certain that Accommodation has reduced to such a level that either distance or near vision must be compromised. A spectacle prescription will then be required to correct either distance or near vision.

Why can some Presbyopes read without reading glasses?

A shortsighted eye can see better up close, but not far. Being shortsighted is like having 'built-in' reading specs! But when a shortsighted presbyope looks through his distance lenses, close vision will be difficult or impossible.

When the eye cannot customise its focus adequately anymore, it needs a spectacle lens to compensate for those distances it cannot see well.

What can be done about Presbyopia?

Researchers are generating and testing various ideas to rid us of Presbyopia, but it is a complicated issue. As yet, there is no way to reverse the changes taking place in the crystalline lens.

For now the only thing we can do when Presbyopia becomes a problem is to wear our reading spectacles.

Some final thoughts

Whether or not you wear reading glasses, they will not weaken your eyes. They are merely experiencing a natural age-related process that started in your 30's and that you are feeling only now. Various eye exercises cannot stop this process either. That is because, as stated above, the problem is due to densifying intra-ocular lenses, not lazy intra-ocular muscles.

But do not worry. This process of change will end at around 55 years of age, after which your reading prescription should remain constant.

Happy reading!