Durban Retinal AssociatesDurban Retinal Associates

The lens of the eye is normally transparent.  If a cloudy area develops in the lens, it is called a cataract.  The function of the lens is to focus the image correctly onto the nerve layer which in turn is transmitted to the brain. The lens is contained within a clear membrane called the lens capsule.  The lens capsule separates the lens from the iris and the transparent, thick fluid called the vitreous body.

The cataract will scatter the light passing into the eye and images are not focused properly on the retina at the back of the eye.  The result is that vision becomes increasingly poor.  This unfocused effect will get worse as the cataract continues to develop.

Cataract formation affects only the lens of the eye and not any of the other important structures, such as the cornea, iris, retina or optic nerve.

A cataract will often worsen to the point where surgery is needed to remove the cloudy lens and replace it with a permanent artificial lens.  There are no drops or medication that can be used to prevent cataract from forming and thus if the lens develops cataract which prevents glasses from correcting the focus, then the only effective treatment is surgery.

Removal of a cataract is the most common eye operation and one of the most common surgical procedures.  It has a high rate of success due to the modern methods used by ophthalmologists.

With older surgical methods, both the lens and the capsule were removed.  With modern methods, however, the capsule is preserved.  This is a significant advance in surgical technique because:

  • The capsule is used to position the artificial lens
  • Risks of surgery are fewer
  • Vision following surgery is usually better

If the eye is healthy, the likelihood is that cataract surgery will restore good vision.  However despite the benefits of modern cataract surgery, there are risks.

Causes and Symptoms

Cataracts develop as a normal part of the ageing process.  By the age of 70, nearly everyone has some degree of cataract formation.  Cataract develops slowly over years.  There are some conditions that will increase the speed with which a cataract develops, for example diabetes, trauma to the eye or excessive ultra violet light. There is no specific age at which cataract becomes visually significant, and so a decision about the timing of surgery is different for each patient.

Cataracts usually develop slowly and at a different rate within each eye.  It may take years before the cataract interferes with a person’s vision.

The earliest symptoms can begin with glare and sensitivity to bright light.  Later, as the cataract continues to worsen, haloes may appear around lights.  Haloes are especially noticeable when driving at night; at the same time, night vision typically decreases.  Vision typically becomes more blurred, hazy and foggy, though near vision without glasses can improve.  Colours often become duller and darker.