What are cataracts?
When you look at an object, light from the object passes through the cornea into the lens of the eye and then through the fluid inside the ball (globe) of the eye. The light hits the retina at the back of the eye which then enables us to see. The lens of the eye acts like the lens in a camera. It helps to focus the light coming in through the eye. For the vision to be clear the lens of the eye has to be clear.
Cataracts develop in the lens of the eye. The lens is mostly made of water and protein. With aging and other causes of cataract, some of the protein may clump together and start to cloud the lens. Over time, this can make it harder to see
A cataract is a gradual build up of the proteins inside the lens. Cataracts have three different formation patterns:
- A nuclear cataract forms deep in the central part of the lens. Nuclear cataracts are usually associated with aging.
- A sub-capsular cataract occurs at the back of the lens. People with diabetes or those taking steroid medications have a greater risk of developing a sub-capsular cataract.
- A cortical cataract begins with white, wedge-like cloudy areas that start in the outer part (periphery) of the lens and work their way to the center in a spoke-like fashion.
Who develops cataracts and how common are they?
Age-related cataract (senile cataract)
Age related Cataracts are the most common type of Cataracts. Cataracts most Often affect both eyes, however one eye may be worse than the other.
Typically, an age-related cataract forms gradually over many years. Many people with an early cataract do not realize that they have it. This is because the cloudiness caused by an early cataract does not have a significant affect on the vision. Most people have their cataract diagnosed at a routine eye check before symptoms ever develop. In some people, the cataract does not become severe. However, in many cases, vision gradually becomes worse as time progresses.
Congenital cataracts (present at birth)
Congenital Cataracts are uncommon but need to be diagnosed as early as possible. A cataract that is present at birth stops the eye from learning to see. It can cause a total loss of vision (severe sight impairment) which may persist even if the cataract is removed later in life. A congenital cataract must be removed as early as possible after birth. This is why doctors examine the eyes of babies as part of routine baby checks.
Other types of cataract
There are some uncommon causes of cataracts. A cataract may develop after an injury to an eye, or as a result of radiation exposure. Using steroid drops in the eye over a prolonged period increases the likelihood of developing a cataract.
Cataracts can sometimes develop as a complication of some other eye conditions. There is an increased risk of cataracts in people who have diabetes.
Some studies have raised the possibility that cataract formation might be related to diet, with the thought that eating less meat or increasing intake of antioxidant vitamins might be helpful. Research continues in this area. However, it is not clear that taking vitamin supplements is of benefit to eye health in those whose diet is already good and well balanced.
What causes age-related cataracts?
The exact cause for cataracts is uncertain. A change to the structure of the proteins causes the proteins to clump together in places in the lens. This causes tiny areas of cloudiness. Each tiny area of cloudiness blocks a bit of light getting through to the retina. The severity of the cataract depends on the number of areas of cloudiness that develop in the affected lens.
Most affected people develop a cataract for no apparent reason. Factors that may increase the chance of developing cataracts include:
- Having a poor diet.
- Having a family history of cataracts.
- Ultraviolet radiation from sunlight and other sources.
- High blood pressure (hypertension).
- Statin medicines used to reduce cholesterol.
- Previous eye injury or inflammation.
- Previous eye surgery.
- Significant alcohol consumption.
- Use of hormone replacement therapy (HRT) for a prolonged period (more than ten years).
- Severe short-nearsightedness (high myopia).
What are the symptoms of age-related cataracts?
At first you may notice your vision becoming a bit blurred. With time, you may notice the following:
- Having spots in your vision.
- Seeing halos around bright lights – for example, street lights.
- Not being able to see as well in brightly lit rooms or in sunshine.
- Becoming easily dazzled by bright lights such as the headlights of an oncoming car.
- Your colour vision may become washed out or faded.
- Over the years your vision may gradually become worse.
- Your visual impairment is not corrected by glasses.
Depending on the severity of the cataract, the effect on your sight can range from vision being slightly blurred to complete blindness in the affected eye.
How is an age-related cataract diagnosed?
A cataract can usually be seen easily by a doctor or optician (optometrist) when they examine your eyes during a routine eye check.
Do I need treatment for age-related cataracts?
An early cataract may not cause any noticeable problem with your vision. The rate of decline in vision varies considerably from person to person. It is now common for people to have their cataract treated at an early stage when the cataract is just beginning to affect ability to function normally. For example, you might be offered surgery if you are having problems reading the paper, watching TV, driving, cooking. Treatment is usually successful.
What is the treatment for age-related cataracts?
When symptoms begin to appear, you may be able to improve your vision for a while using new glasses, appropriate lighting or other visual aids.
There are no medicines, eye drops or lasers that can treat cataracts. The only way of treating cataracts is with surgery. This is a very common operation.The operation involves removing the cloudy lens and replacing it with an artificial lens (an intraocular implant).
It is a routine operation that usually takes 10-20 minutes. It is often done as a day case. The majority of people who have cataract surgery experience a marked improvement in their vision.
The decision on whether or not to have cataract surgery is a personal one which you should make after talking to your doctor or eye specialist. It will be affected by factors such as your general health and fitness, your wish to read or drive and the presence of any other eye problems which might mean that removing the cataract will not restore your vision.
What happens during a cataract operation?
The operation is performed, using a microscope, through a very small opening in the eye. When the eye is numb, the surgeon makes a tiny hole in the front of the eye at the edge of the cornea. Then, the surgeon removes the inside of the lens. He/she may first break up the lens with ultrasound to allow it to be extracted through a smaller incision (this technique is called phacoemulsification).
A clear plastic lens is placed within the lens capsule. Usually no stitches are needed. You may have to wear a pad over your eye after the operation.
The standard plastic lens can’t change its focus to look at near objects versus distant objects, for example. So, if you have a standard plastic lens inserted you will still need to wear glasses (if you did before the operation).
It is sometimes possible to have an accommodating lens inserted which allows focusing on near as well as distant objects. Multi focal lenses which are even more versatile are now also available. Your surgeon will be able to discuss with you whether these are suitable for you.
Normally one eye is operated on at a time. The operation is usually done under local anesthetic, so you are awake during the operation. The operation should be painless, as local anesthetic eye drops are used to numb your eye. (Occasionally, local anesthetic injections are also used around the eye.)
Cataracts and driving
Cataracts may affect your ability to drive, either:
- By visual clouding (if severe); or
- By causing pronounced glare which can dazzle you when driving at night.
It is your legal obligation to inform the Ministry of Transportation about any medical condition which could affect your safety behind the wheel. If you are uncertain, you should discuss this with your doctor and/or optician (optometrist).