What is a cataract?
Cataract occurs as a result of clouding of the naturally clear lens in the eye. A clear lens is essential to focus light, or an image, onto the retina (the photoreceptor). In a normal eye, light passes through a transparent lens to the retina. Once it reaches the retina, light is changed into electrical signals that are sent to the brain to be interpreted as an image. The lens must be clear for the retina to receive a sharp image. If the lens is cloudy (due to cataract), the image you see will also be blurred.
Causes of the cataract
Most cataracts are age-related. Majority of elderly people who are older than 50 years old will have some amount of cataract affecting their vision. It may be the result of a lifetime exposure to ultraviolet radiation contained in sunlight during their daily activities, or may be related to other lifestyle factors such as cigarette smoking, diet, and alcohol consumption. Cataract can also occur much earlier as a result of eye trauma, exposure to toxic substances / radiation, or following certain diseases such as diabetes mellitus. It can also be secondary to taking medication such as steroid for a long time. A small minority of cataracts may even be present at birth due to genetic defects, developmental abnormality or exposure to diseases such as rubella during pregnancy. These are known as congenital cataracts.
What are the symptoms of a cataract?
Cataract started to develop in your eyes as early as 40 years old. Initially, most cataract is mild and do not affect vision. With time, cataracts worsen and eventually reduce your quality of vision in one way or the other. Symptoms usually develop over many years and these include:
- Cloudy or blurry vision.
- Colors seem faded.
- Glare with headlights, lamps, or sunlight.
- A halo may appear around lights.
- Poor night vision.
- Double vision or multiple images in one eye.
- If you wore glasses, you may find that they have become less effective and therefore need to change the power of your glasses or contact lenses frequently.
Typically, these symptoms occur slowly without any eye pain and progressively worsen with time. Early detection is essential.
How is a cataract detected?
If you have problems with your vision, you should consult your ophthalmologist. They will be able to detect the presence as well as the severity of your cataract. Sometimes, cataracts are diagnosed during a routine eye test, even if you have had no visual symptoms.
How is a cataract treated?
Cataract can only be treated with a surgery which involves removal of the cloudy lens and implantation of an artificial biocompatible clear plastic lens, called an intraocular lens (IOL), into the eye. The lens sits in a little ‘pocket’ (the lens capsule) to keep it in place. The lens is folded when it is inserted. Once in position, it is allowed to unfold. This IOL then becomes a permanent part of your eye, taking over the optical function of our natural lens to focus light onto the retina, thus improving your vision. After the procedure, you will not feel or see the new lens, nor does it need any extra eye care.
What are the different types of cataract surgery?
There are two types of cataract surgery: Phacoemulsification or phaco (small incision cataract surgery) is the surgery of choice currently. This is a keyhole surgery done under local anesthesia. It involves inserting a tiny probe into the eye through a small incision made on the side of the cornea (the clear surface that covers the front of the eye). The tip of this probe emits ultrasonic waves that break the lens into smaller pieces which can then be sucked out. Because the incision is so small, it is self sealing and no stitches are required after the procedure. This has greatly reduces the cornea unevenness and produces a very good visual outcome. Visual recovery is fast and patient usually can see well within the first post-operative day.
Extracapsular surgery. In this procedure, a longer incision on the side of the cornea is made to remove the cataractous lens in one piece. Because the incision is much bigger, hence multiple stitches are required to close the wound.
The replacement lens
Different types of replacement lens are available. For example:
- fixed strength lenses (monofocal) – set for one level of vision, usually distance vision,
- multifocal lenses – allow two or more different levels of vision, ie near and distance vision, and
- Accommodating lenses – allow the eye to focus on both near and distant objects, in a way similar to the natural human lens.
What are the risks of cataract surgery?
Cataract surgery is a relatively safe surgery with minimal risks, such as infection and bleeding. The risk of complications in cataract surgery is less than 1 in 100. Before and after the surgery, you will be reminded of certain precautions in order to minimize the risk of the surgery. You must keep your eye clean, wash your hands before touching your eye, and use the prescribed medications accordingly to help minimizing the risk of infection.
What can I do to protect my vision?
Unfortunately it is not possible to prevent cataract. Wearing sunglasses and a hat with a brim to block ultraviolet sunlight may help to delay cataract. Adopting a healthy life style with no smoking and excess alcohol consumption is also helpful. Researchers also believe good nutrition can help to delay the development of age-related cataract. They recommend eating green leafy vegetables, fruit, and other foods with antioxidants. In summary, if you are 50 years old or older, you should have a comprehensive dilated eye examination at least once a year for early detection of cataract, age-related macular degeneration, glaucoma and other vision disorder. Timely and appropriate treatment of cataract will improve your vision and allow you to enjoy a better quality of life.
Dr Sim Pek Eng, Consultant Opthalmologist & Refractive Surgeon
Gleneagles Kota Kinabalu Hospital