What is a cataract?
A cataract is a clouding of part of your eye called the lens. Vision becomes blurred or dim because light cannot pass through the lens to the back of your eye.
What causes cataract?
Cataracts can form at any age, but most often develop as people get older.
You may notice that some things seem blurred round the edges, or that your glasses seem dirty or scratched. Bright light or very sunny days make it more difficult to see. As the cataract develops its centre becomes more yellow, giving everything a yellowish tinge.
What can be done to help?
The most effective treatment for cataract is a small operation to remove the cloudy lens. The lens is usually replaced by a plastic implant which helps the eye focus properly. With modern surgery the operation can be carried out at any stage of the cataract's development when visual impairment interferes with your ability to read, work or your quality of life.
What is glaucoma?
Glaucoma is the name of an eye condition in which the optic nerve is damaged at the point where it leaves the eye. The eye needs a certain amount of pressure to keep its shape so that it can work properly. In some people, the damage is caused by raised eye pressure. Others may have an eye pressure within normal limits but damage occurs because of a weakness in the optic nerve.
The most common form of glaucoma is chronic glaucoma where eye pressure rises very slowly but there is no pain to show there is a problem. If untreated, over a period of time, the field of vision gradually becomes impaired. Chronic glaucoma is more common with increasing age. It is uncommon below the age of 40, affecting 1% of people over this age and 5% over 65. If you have a close relative who has chronic glaucoma, then you should have regular eye tests. This is especially important if you are age over 40.
Acute glaucoma is much less common. This happens when there is a sudden rise in eye pressure. It can be quite painful and will cause permanent damage to your sight if not treated properly.
How is glaucoma detected?
Tests for chronic glaucoma are carried out as part of a regular eye test. Viewing the optic nerve by shining a light from a special torch into your eye, measuring the eye pressure using one special instrument and testing your fields of vision with another, which shows a sequence of spots of light on a screen.
A sudden increase in eye pressure can be very painful. The affected eye becomes red and sight deteriorates. Vision may seem misty with coloured rings around white lights. There may even be nausea and vomiting.