CLEAR TO CLOUDY

As light enters the eye it passes through the lens reaching the retina which transmits visual signals to the brain via the optic nerve. A cataract develops when the proteins in the lens form clumps turning the lens from clear to cloudy and preventing clear images from being sent to the brain. It develops slowly, darkening with a yellow or brown tinge, worsening over time and gradually interfering with vision. Cataracts are common in older people but can occur in younger people.

How Cataracts Affect Vision

Initially cataracts may have little effect on vision, but the effect typically increases as the cataract progresses. The most common symptom of cataracts is blurry or cloudy vision. Other symptoms include difficulty with night vision, increased sensitivity to glare and bright lights, halos surrounding lights, double vision, frequent changes to glasses or contact lens prescription and faded colour vision or difficulty distinguishing certain colours. Some people experience "second sight". Due to the cataract acting as a stronger lens, near vision temporarily improves; however, as the cataract worsens, this temporary improvement disappears.

Types of Cataracts

There are three main types of cataracts, affecting different parts of the lens. They are classified according to where and how they develop. Nuclear cataracts form in the centre of the lens, cortical cataracts are situated on the side of the lens, and posterior subcapsular cataracts affect the back of the lens and develop faster than the other two types. Other, less common types of cataracts are secondary cataracts which are caused by disease or medications, traumatic cataracts as a result of eye injury and congenital cataracts which are present at birth or develop during a baby's first year.

Causes of Cataracts

Although it is not precisely understood why people develop cataracts, there are several underlying causes and risk factors. Aging is a known risk factor and family history may have a significant role to play. Exposure to the ultraviolet rays of the sun, smoking, excessive alcohol use, certain medical conditions, long-term use of certain medications such as corticosteroids, trauma to the eyes and previous eye injuries may contribute to the development of cataracts.

Diagnosing Cataracts

Cataracts are diagnosed with a comprehensive eye examination. Your optometrist will assess your visual acuity at various distances, examine your eyes using a slit lamp microscope, test the pressure within the eyes and dilate your pupils to enable him or her to have a clear view of the retina at the back of the eye. Other tests may include your perception of colours and sensitivity to glare.

Treatment of Cataracts

As they progress, cataracts can interfere with daily activities and surgical removal is usually recommended. Cataract surgery involves removing the cloudy natural lens and replacing it with an artificial lens. It is a common procedure, is generally safe and has a high success rate. Your optometrist will refer you to an ophthalmologist who will discuss the various surgical options available.

After corrective surgery for cataracts, you may be surprised to see the world with all of its colours again. As one person expressed it: "Having always worn glasses since young and living with poor vision, I woke up the next day after having my cataract removal surgery to what seemed like a miracle. Seriously, I never imagined after so many years, now that I'm in my 60s to be able to wake up look at the clock and tell what time it is."

Prevention of Cataracts

While it may not be possible to prevent the development of cataracts, the risk of developing them may be reduced by protecting the eyes from UV rays by wearing sunglasses, giving up smoking, following a diet rich in antioxidants, monitoring chronic health conditions and having regular eye examinations.

It is important to be aware that not all vision changes are the result of cataracts. Several of the symptoms described can be signs of other eye conditions and sometimes general health conditions. Regular eye examinations may result in early detection and management of potentially serious problems.