Mr Nicholas Glover - What is a cataract
Mr Nicholas Glover  - Consultant Cataract & Vitreoretinal Surgeon



 





What is a   Cataract

Cataracts are a very common eye condition. As we get older the lens inside our eye gradually changes and becomes less transparent (clear). A lens that has turned misty, or cloudy, is said to have a cataract. Over time a cataract will gradually making your vision mistier. 

A straightforward operation can usually remove the misty lens and replace it with an artificial lens to enable you to see more clearly again.


When you look at something, light passes through the front of your eye, and is focused by the cornea and then the lens onto the retina. The lens is normally clear so that light can pass directly through to focus on your retina. The lens focuses light onto the retina, which converts the light into electrical signals. These signals from the different parts of the retina form the optic nerve and then onto the brain.

The lens can change shape, allowing us to focus on objects at different distances, called "accommodation of vision". As we get older, the lens isn't able to change shape as well as it used to; and even people who can see clearly in the distance without glasses will need reading glasses to see things up close. This is called prespyopia and is not caused by a cataract.

A cataract is not a growth or a film growing over the eye, it is simply the lens becoming misty.

Causes

Cataracts can be caused by a number of things, but by far the most common reason is growing older. Most people over the age of 65 have some changes in their lens and most of us will develop a cataract in time. 

Cataracts usually develop slowly and although symptoms vary there are some symptoms that most people experience. Most people will eventually develop a cataract in both eyes, though one eye may be affected before the other. 

When your cataract starts to develop, you may feel your sight isn't quite right. For example, if you wear glasses you may feel that your lenses are dirty, even when they're clean. Gradually, you may find your sight becomes cloudier and more washed out. Edges of stairs or steps become more difficult to see and you may feel you need a lot more light to read smaller print.

Another common symptom of a cataract is a problem with bright lights. Lights can seem to glare, or you may find that the headlights of a car dazzle you more than they used to. 

You may also notice a slight change in your colour vision - things may appear more yellow than before. This often happens if one eye develops a cataract first and colours look different when you compare one eye with the other.

If you notice any of these changes, you should have your eyes tested by an optician who will be able to tell whether you have a cataract or not. 

The optometrist will then discuss the degree to which the cataract is affecting your vision and if you agree, refer you via your GP to the eye clinic. 

You may be told during the eye test that you have early cataract or initial signs of a cataract which does not need referral. Eye tests are free for everyone over sixty years old in the UK.

If a cataract isn't removed, your sight will become increasingly cloudy. Eventually, it will be like trying to see through a frosted window or a heavy net curtain or fog. Even if your cataract gets to this stage, it can still be removed and your sight will recover.