Derby Eye Surgery
Normal Ageing of the Eye lens

To understand cataract and modern surgical treatment, it’s worth quickly considering the anatomy of the eye and the effect of ageing on its focusing system.

The anatomy of the eye.

The eye is constructed in many ways like a camera. It has a lens system which focuses light onto the light sensitive “film” called the retina. The front window or cornea acts together with the internal lens to do the focusing. In young people the lens can change shape and therefore it’s focusing power. When looking at a distant object the lens has it lowest focusing power. For the eye to focus on something closer, the lens has to become more curved to make it optically stronger. The eye can do this by using its internal muscles to change the lens shape. This process is called accommodation.

As we age, our eye loses the ability to focus close up. This is because the lens hardens and can no longer change its shape to become more curved. As a result, people who previously did not require glasses find everything is blurred close up. They end up needing reading glasses. This is a normal part of ageing and is called presbyopia.

It’s more complicated for those people who have always worn glasses either because they are long or short sighted (see refractive errors in the children’s eye problems section).

A short-sighted person needs glasses to help them see in the distance. Their eyes, in effect, are too strong and their glasses weaken the focusing power of the eye. Whilst wearing their glasses they will still need to increase the focusing power of their eye’s lens to see close up. As they get older they cannot do this as easily and they too need reading glasses (actually less weakening glasses than they use to see in the distance). However they have the option of simply taking off their distance glasses and using their abnormally strong eyes to see close up. It’s a hassle taking glasses on and off so most people use bifocal glasses to use both for distance and near vision.

Longsighted eyes are too weak. They need glasses that strengthen the focusing power of the eye. They may need to use glasses even for looking in the distance but especially so when looking close up. When they get older they need even stronger glasses to look close up. If they take off their glasses they are blurred for distance and even more so for close up. They almost always will use some form of bifocal glasses, though some people still prefer separate distance and reading glasses. For older longsighted people, reading without glasses is not an option.

General eye problems

Adult Squint
Presbyopia and normal ageing of the eye
Cataract FAQ's
Refractive surgery of the lens and correction of presbyopia
Dry eye
Retinal Vein Occlusion


Derby Eye Surgery

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 Roger Holden Eye Surgeon
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