A cataract is a clouding (opaqueness) of the normally clear lens of the eye, which can interfere with vision. Cataracts are inevitable, to some degree, as we get older. Many Australians will have some degree of cataract by the age of 70 years.
The lens of the eye is normally clear and focuses the light entering the pupil onto the retina (the light-sensitive layer at the back of the eye) to produce sharp images. A cataract scatters the light, blurring the images on the retina.
What are the symptoms of cataracts?
Cataracts tend to develop slowly, and at first you may not notice any symptoms. As the cataract gradually gets larger and affects more of the lens in your eye, symptoms become more noticeable.
Symptoms of cataracts include:
- sensitivity to glare and bright lights;
- seeing haloes or starbursts around lights;
- seeing colours as faded or yellow; and
- blurred, foggy or hazy vision.
Typically, people with cataract complain about difficulty with:
- reading, especially in dim light;
- recognising faces (or facial expressions); and
- driving at night.
You may experience double vision, but this is rare.
Cataracts usually develop in both eyes, rather than just one. However, a cataract in one eye may be more advanced and cause more symptoms that a cataract in the other eye.
Can cataracts result in loss of sight?
People with untreated, advanced cataracts in both eyes can lose their sight. In fact, cataracts are the leading cause of impaired vision (blindness) worldwide. However, the good news is that for most people, once their cataracts are treated, sight can be restored.
In Australia, most people will be treated for cataracts well before their eyesight is threatened.
What are the causes of cataracts?
Most cataracts develop as a result of ageing. Ageing is thought to affect the proteins in the lenses of the eyes, resulting in clouding of the lenses.
Factors that can increase your risk of developing cataracts include:
- long-term unprotected exposure to UV sunlight;
- excessive alcohol intake;
- high blood pressure;
- a family history of cataracts;
- injury to the eye;
- previous eye surgery;
- prolonged exposure to X-rays or radiotherapy;
- chronic inflammation in the eye;
- poor nutrition; and
- use of corticosteroid medicines for a prolonged time.
Cataracts can sometimes affect babies and children. Some cataracts are caused by inherited genetic disorders or other illnesses that affect children or their mothers during pregnancy. Rubella infection during pregnancy can cause cataracts that are present from birth (congenital cataracts).
Your doctor, eye specialist or optometrist will ask about your symptoms and perform an eye examination.
Cataracts can be diagnosed using an ophthalmoscope – a hand-held instrument with a light and magnifying lens that is used to examine the inside of the eye. You may have some eye drops put in your eyes beforehand to dilate your pupils so that your doctor can examine your eyes thoroughly.
Another way to examine your eyes is using a slit lamp, which allows your doctor or optometrist to see the structures in your eye, including the lens, under higher magnification. Slit lamp examinations can provide more details about the location and size of cataracts.
What is the treatment for cataracts?
Surgery is the only cure for cataracts. Your doctor will refer you to an eye specialist (ophthalmologist), who can discuss the risks and benefits of cataract surgery with you.
The decision to operate depends entirely on how much the cataract interferes with your vision and your ability to perform your usual activities.
Because cataracts usually progress slowly, you may wish to delay cataract surgery if you are currently experiencing only minor symptoms. In the meantime, you can:
- wear eyeglasses or contact lenses to help correct blurred vision;
- wear sunglasses and a hat to reduce the effects of glare; and
- improve the lighting in your home. (For example, for tasks such as reading use a bright lamp that directs light over your shoulder.)
If your eyesight has deteriorated to the point that you are having trouble participating in your usual activities, your doctor may recommend surgery.
In cataract surgery, the clouded lens is removed and usually an artificial, clear lens implant is inserted in its place. The lens (called an intraocular lens – IOL) is usually made of plastic or silicone.
The operation is usually done under local anaesthetic and light sedation. The procedure is short – it takes 20 to 30 minutes – and is usually done as day surgery (meaning you can go home on the same day as the surgery).
If you have cataracts in both eyes, surgery is usually done one eye at a time, usually several months apart.
After the surgery
Eye drops may be needed for several weeks after the surgery to prevent infection and inflammation.
Certain activities should be avoided for several weeks following cataract surgery, including strenuous activity, heavy lifting, bending over and eye rubbing. You may also need to wear a protective eye mask while sleeping.
After the surgery, you may no longer need glasses (or contact lenses) to see clearly. Alternatively, your prescription may change or you may only need glasses for certain activities (many people still need glasses for reading).
Can cataracts come back after surgery?
Cataracts do not come back after surgery. However, in some people the tissue surrounding the lens can become cloudy and affect your vision. If this happens, a minor procedure involving laser treatment can treat the problem.
There are some things that may help delay or prevent the development of cataracts. These include:
- Wearing sunglasses to protect your eyes from UV light – wearing sunglasses in your younger years might help you avoid or postpone the development of cataracts.
- Quitting smoking if you smoke.
- Reducing your alcohol intake.
- Eating a healthy diet that includes plenty of fruit and vegetables. A diet high in fruit and vegies contains plenty of vitamins and minerals, which may help reduce the risk of cataracts. Vitamins A and C are thought to be particularly helpful in preventing cataracts. Fruit and vegetables are also a good source of antioxidants, which are important for eye health.
2. Mayo Clinic. Cataracts (updated 21 Apr 2016). http://www.mayoclinic.org/diseases-conditions/cataracts/basics/definition/con-20015113 (accessed May 2016).
3. Merck Manual, Professional Version. Cataract (updated July 2014). https://www.merckmanuals.com/professional/eye-disorders/cataract/cataract (accessed May 2016).
4. BMJ Best Practice. Cataracts: should I have surgery (updated 16 Sep 2015). http://bestpractice.bmj.com/best-practice/pdf/patient-summaries/531954.pdf (accessed Jun 2016).