A cataract is a growth over the lens of the eyeball that disrupts vision. Cataracts do not progress quickly so disrupted vision usually doesn't occur until a patient has had the cataract for some time, according to Cleveland Clinic.
The most common cause of cataracts in the eye is age and sometimes an injury to the eye can cause them, states Mayo Clinic. Other rare things, such as a genetic disorder can also cause a patient to develop cataracts in the eye. Essentially, a cataract disrupts the way the lens takes in light and that in turn, makes the persons vision appear to be cloudy. Not only do they effect the center of the lens, they can also interfere and develop on the edges and at the back of the lens, as stated by Mayo Clinic.
Most patients will first notice a glare when looking at something with lights on it, if they have a cataract in the eye. Before clouding of vision develops, a person may notice vision changes in both distance and near sight. Once the cataract has grown to become a nuisance with the patients eyesight, the only option for treatment is surgery which is when a surgeon goes in and physically removes the cataract from the eye.