The lens of the eye is normally transparent. If a cloudy area develops in the lens, it is called a cataract. When the amount of light that passes through the lens is reduced and scattered by the cataract, images are not focussed properly on the retina at the back of the eye. The result is that vision becomes increasingly poor. 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.
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.
Removal of a cataract is the most common eye operation and one of the most common surgical procedures performed in Australia and New Zealand. It has a high rate of success due to the modern methods used by ophthalmologists. If the eye is healthy, the likelihood is that cataract surgery will restore good vision. Of every 100 operations to remove a cataract, 95 will result in significantly improved vision. Despite the proven benefits of modern cataract surgery, there are risks.
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.