Cataract is where the natural lens inside the eye becomes cloudy or opaque. The pupil is a hole through which light passes to form an image at the back of the eye. Immediately behind the pupil is a lens which is normally clear; if it becomes hazy this will affect the quality of image seen by the patient.
The most common form of cataract is age-related and typically occurs over 70 years of age, but occasionally can occur at a much younger age.
Cataract may have other causes:
• Congenital (present at birth)
• Secondary to eye problems such as iritis
• Secondary to general health problems such as diabetes
• Infra-red or ultra-violet light
People with early cataract may not experience any symptoms at all. As the cataract worsens it may cause:
• Blurring of vision
• Significant and often rapid changes in spectacle prescription
• Glare in bright light
• Reduced ability to see subtle changes in contrast
• Changes in colour perception
• Can cause doubling of images in one eye.
In the early stages this is often best achieved through up-to-date glasses and regular check-ups. It is also important to control illumination to avoid glare, for example by wearing a hat with a brim. Improving lighting for reading with an angle-poise lamp and avoiding night driving can also help.
When cataract develops to the point where it is reducing quality of life then it may be appropriate to consider surgery. Cataract surgery is generally very successful and involves removal of most of the lens and replacing it with a plastic implant lens, usually under local anaesthetic in a procedure lasting about 20 minutes. This is carried out in hospital by an ophthalmologist. After the operation patients need eye drops to prevent infection, usually for about 4 weeks, and apart from avoiding bending or strenuous activity for a while, can return to normal very soon.
When should I have my cataract removed?
Nowadays you don’t have to wait until a cataract is ‘ripe’. For anyone who is contemplating surgery they should be balancing risk against benefit – in a normal eye there is about a 1 in 1000 risk of loss of vision in the eye during or after surgery. This is very low, but it is a risk, and should be balanced against how much the cataract is affecting the quality of life.
The eye normally settles quickly after surgery and patients will usually require new glasses 3-4 weeks after the operation. Most people find a marked improvement in vision, not just in clarity, but things look brighter and colours are more vivid too. The cataract can’t grow back but in a few people a membrane grows over the implant and reduces vision again. In this case the ophthalmologist can use a laser to remove the membrane in a straightforward procedure and vision should be fully restored.