Cataract Surgery: Definition
A cataract is a loss of transparency in the lens.
Together with the cornea, the lens, which is positioned directly behind the pupil, focuses rays of light onto the retina. For a whole range of reasons, the most common of which is old age, the lens may begin to lose its transparency and become opaque. The cataract starts to limit the patient’s vision to a greater or lesser degree depending on the position of the cataract in the lens and the degree of opacity that is produced.
Depending on the position of the cataract, they can be defined as: nuclear cataracts, which affect the centre or nucleus of the lens; subcapsular cataracts, which affect the membrane at the back of the lens; capsular cataracts, which cover the lens; or cortical cataracts, which begin on the outer edge of the lens or cortex.