Proteins, suspended in water and aligned in a clear crystalline array, are the elements for a structure in the eye called the lens. The lens gathers light rays admitted by the cornea and focuses them onto the retina creating the images of the world that you see in your mind. Due to many conditions the precise alignment of proteins in the lens may break down and the proteins clump together forming clouds. These protein clouds are called cataracts. Cataracts block some light from reaching the retina thus interfering with your vision.
Cataracts may result from many conditions including congenital defect, chronic eye disease, system-wide diseases (diabetes), or eye trauma, but by far the most common cause of cataracts is simply age. Cataracts are the leading cause of vision loss among older American. More than half of all Americans 65 years of age and older have some degree of cataract development. By the time you are between 75 to 84 years of age there is better than a 90% chance that you have a cataract. Although cataracts cannot be prevented they can be effectively treated surgically. Cataract surgery is the most common surgical procedure performed on Americans aged 65 years and older. 95% of cataract surgeries result in an improvement in vision in otherwise healthy eyes.
In the initial stages of cataract development you may not notice any vision change because the cataract is small. Cataracts tend to grow slowly so vision deteriorates slowly. Some people with a cataract find that their close-up vision suddenly improves, but this temporary effect dissipates as the cataract grows. Common symptoms of a cataract are: