Presbyopia is the gradual loss of near sight that occurs from the age of 40. It is not an eye disease but a symptom of the aging process. It is different from farsightedness, or hypermetropia, which is caused by a fault with the shape of the cornea and can affect people of any age.

In young eyes, the incoming light is focuses by the cornea and the lens on to the back of the eye. The lens is flexible and can change shape to alter its focal length, allowing you to focus on objects at different distances. This change is brought about by small muscles called the ciliary body, which are attached to the lens via suspensory ligaments. As the muscles tighten, the ligaments become lose and the lens becomes more curved, bringing closer objects into focus.

With age, the lens becomes less flexible and the muscles less effective in changing its shape. This means that you are no longer able to see objects or text close to you as clearly as you once did.

Who does presbyopia affect?

Presbyopia is an inevitable result of the aging process. It can start in some people from the age of 35 but is more common in the over 40s. By the age of 45, most people will have noticed some problems with their close up vision.

You may be more vulnerable to presbyopia if you are involved in a lot of close up work as part of your job, or if you work outdoors, particularly in summer or in hotter climates, and your eyes are exposed to a lot of UV radiation.

What are the symptoms of presbyopia?

Since presbyopia is a slow, degenerative process, you may only notice gradual changes in your vision over time. Typical problems include:

• Struggling with small print.
• Problems with reading reversed or white on colour text.
• A need to hold things further away to see them clearly.
• Headaches.
• Eyestrain.

Presbyopia progresses through a number of stages:

• Incipient presbyopia – in which you start to notice occasional problems.
• Functional presbyopia – in which the problems become more frequent.
• Absolute presbyopia – in which you can no longer focus at all on close up objects.

You may also experience nocturnal presbyopia, in which close focus becomes difficult in low light conditions.

How is presbyopia treated?

For a long time, the only solution to presbyopia was glasses or contact lenses. These have become quite sophisticated in recent years, with varifocal glasses and contact lenses allowing for the correction of both short sight and presbyopia with a single lens. However, this is not ideal, and many people would prefer not to have to wear glasses or have the inconvenience of contact lenses.

Today, private eye surgery offers several techniques that can treat presbyopia successfully. With some techniques you may need to wait until your vision has been stable for 12 months but surgery can improve close vision and enable you to be glasses-free for several years. Surgery is done as a day case and recovery is rapid and most people no longer need to wear glasses or contact lenses afterwards.

Surgery for presbyopia

Techniques used to treat presbyopia are being constantly refined but the main ones include:

LASIK monovision laser eye surgery

One eye is treated with LASIK surgery so that it becomes slightly short sighted. The other eye still has normal long-sighted vision. Over a few weeks, the brain becomes acclimatized to processing images from both eyes and combining them, resulting in good near and far vision. It does take time to get used to and most clinics offer a disposable contact lens trial before surgery so that you can find out if this works for you.

Refractive lens exchange or presbyopic lens exchange

This technique is based on the same lens replacement techniques used to treat cataracts. The old, inflexible lens is removed with precision laser surgery and replaced with a flexible artificial lens. Different types of lenses are available:

• Multifocal lenses: if you also have underlying short sightedness, a multi-focal lens can be used to correct both conditions simultaneously.
• Trifocal lenses: a technological improvement on the older multifocal lenses, these give good middle distance vision too, and improve your vision in poor light or at night when driving.
• Light adjustable lenses: this is a new and state-of-the-art technique. A special lens is implanted and two weeks after surgery, the shape of the lens is adjusted by shining UV light onto it in a controlled way. This polymerises substances in the lens, moulding it into the shape required to give perfect vision.
• Accommodating lenses: also very advanced, these lenses contract and expand, mimicking the eye’s natural lens when in perfect condition, restoring the same level of vision and accommodation you had in your twenties.

The added advantage of opting for lens replacement surgery to treat presbyopia is that since the aging natural lens is removed, you will no longer be at risk of developing cataracts in later life.