The crystalline lens is situated behind the Iris, the coloured part of the eye.
The purpose of the lens is to focus light onto the retina, the sensory surface on the back of the lens. Over time, the lens can become cloudy causing disrupting the clarity of vision, leading to a cataract.
Symptoms of a cataract developing can include blurred vision, double vision, changes in colour perception, and even sensitivity to lights. In the early stages of cataracts, correcting the vision with spectacles and contact lenses can be appropriate. If there comes a stage where an optical prescription cannot reduce the symptoms, removal of the cataract can be appropriate.