The lens is near the front of your eye, just behind your iris – the coloured part of your eye. Your lens is normally clear and helps you to see things in focus. It directs light rays on to the back of your eyeball (retina), to form an image, which is then sent to your brain. Your lens can change its shape to allow you to see things near and far away. If your lens becomes cloudy from a cataract, your vision will become blurred.
There are three main types of cataract.
- Nuclear cataracts. These may make it difficult for you to recognise the intensity of colours. If you have nuclear cataracts, your reading vision won’t normally change.
- Cortical cataracts. These can cause you problems with glare if you drive. You may also have difficulty reading and find sunlight uncomfortable during the winter because of the sun being lower on the horizon and shining into your eyes.
- Subcapsular cataracts. These can make your vision poor during the daytime, making it difficult for you to drive. You may also have difficulty reading.
Your symptoms will depend on where your cataract is on your lens, its size and if you have a cataract in one or both eyes. The most common symptoms are listed below.
- Cloudy or blurry vision.
- Frequent changes to the prescription of your glasses or contact lenses.
- You may get more glare or see halos from lights or the sun. It may make driving at night difficult because of the glare caused by oncoming vehicle headlights.
- Colours may seem washed out or faded.
These symptoms may be caused by problems other than cataracts. If you have any of these symptoms, see your optometrist (a registered health professional who examines eyes, tests sight and dispenses glasses and contact lenses) for advice.
If you think you have symptoms of cataracts, you should have your eyes tested by an optometrist. He or she will look into your eyes using a special instrument called an ophthalmoscope. Your optometrist will refer you to an ophthalmologist (a doctor specialising in eye health) if he or she suspects you have cataracts.
Eye tests using standard charts will help identify worsening eyesight. It's quite common to be diagnosed with a cataract during a routine eye test without having any symptoms as changes in the lens tend to occur gradually over many years.
Wearing glasses and using brighter lighting may improve your vision to begin with, but your cataracts will probably get worse over time, so this will only be a temporary solution.
So far, no medicine has been found to slow down the development of cataracts, and there isn't a medicine or eye drop that can clear a clouded lens.
Replacing your cloudy lens with a new, artificial lens is the only way to improve your vision. The most common operation for this is called phacoemulsification. This usually takes about 30 minutes. The cloudy lens is destroyed with sound waves and taken out, and a lens made of a clear, artificial material, such as plastic or silicone, is put in. This is usually done under local anaesthesia or with anaesthetic drops. The anaesthetic completely blocks the feeling from your eye area and you will stay awake during the operation.
If you have a cataract in both eyes, the surgery to remove each one will be done at different times – usually four to eight weeks apart.
Cataracts are caused by changes in the structure of the lens of your eye. This is usually as a result of getting older.
There are other factors that may increase your risk of getting cataracts. These include:
- an injury to the eye
- other eye problems, such as uveitis
- exposure to ultraviolet (UV) light from sunlight
- long-term use of steroid medicines
- drinking too much alcohol
- a family history of cataracts
If left untreated, cataracts may eventually lead to blindness. However, cataracts are normally diagnosed and treated well before they severely affect your vision. Left untreated, your lens may become so cloudy that it will be like trying to see through fog.
Can I drive if I have cataracts?
This depends on how advanced your cataract is and if your sight is within the legal limits for driving.
By law, your vision must meet set standards in order to hold a driving licence. These criteria are set by the Driving and Vehicle Licensing Agency (DVLA).
The DVLA requires you to be able to read a vehicle's registration plate in good light, while wearing glasses or contact lenses if you use them, from 20 metres away (20.5 metres for a registration plate older than September 2001). You shouldn't drive if you can't read from this distance. You may find that glare is a problem (for example, from oncoming vehicle headlights when driving at night), even if your vision is otherwise fine.
If you're concerned whether your vision meets the DVLA standards, book an eyesight test with your optometrist (a registered health professional who examines eyes, tests sight and dispenses glasses and contact lenses). If your eyesight isn't good enough to drive but you wish to keep driving, you will need cataract surgery. If the vision in your other eye is good, you can still meet the driving standards (although it can take time to adapt to driving with good vision in only one eye).
Your ophthalmologist (a doctor specialising in eye health) will advise you about when you’ll be able to drive again after surgery.
Can my cataract come back if I have it removed?
No, a cataract can't come back once it has been removed.
Your new lens will be designed to last a lifetime so once you have had your cataract surgically removed, it won't come back again. However, it's possible to get a cataract in your other eye.
It's not uncommon to develop a condition after surgery called posterior capsule opacification (PCO). This makes your vision cloudy, but it isn't the same as having a cataract. It's caused by a thickening of the natural lens casing – the part of your eye that holds your lens in place. This lens casing isn't usually removed during surgery but holds the new lens that replaces the cataract.
PCO can develop within two months or it may take several years after having surgery. You will need a relatively minor procedure using a laser to correct your vision. The procedure (known as a capsulotomy) is quick and painless. Your pupil will be dilated with eye drops and anaesthetic drops will be given. You will be asked to sit with your chin resting on a machine and a special contact lens will be applied to the surface of your eye. The surgeon directs the laser with the aid of the contact lens to break the cloudy centre of your lens casing. Your vision will usually be restored straight away, although very occasionally you may get inflammation, which will require further treatment.
How quickly will I lose my sight?
This varies considerably from person to person.
Your vision will probably keep getting worse if you don't have your cataract removed. This can happen slowly, sometimes over a number of years. People often don't know they have cataracts because the changes are gradual. At first, you may find that your sight isn’t quite right. It may gradually become cloudier and more washed out. The speed at which your sight gets worse varies from person to person, and may be faster in one eye than the other.
As long as your visual loss is only caused by the cataract, then even if you do reach a level where you have almost completely lost your sight, your vision can usually be restored with surgery.
- Cataracts. Prodigy. www.prodigy.clarity.co.uk, published September 2010
- Cataracts. Royal National Institute of the Blind. www.rnib.org.uk, published 30 May 2012
- Facts about cataract. National Eye Institute. www.nei.nih.gov, accessed 14 June 2012
- Senile cataract. eMedicine. www.emedicine.medscape.com, published 9 March 2012
- Understanding cataracts. The Royal College of Opthalmologists. www.rcophth.ac.uk, published November 2011
- At a glance guide to the current medical standards of fitness to drive. Driver and Vehicle Licensing Agency (DVLA). www.dft.gov.uk, published 14 March 2012
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