Cataract is the film that grows on the Eyes causing the image to be doubled or they see the double image.
The Cataract does not form on the Eye but within the Eye.
The Cataract is the clouding of the natural Lens. The Lens is the part of the Eye that focuses the light and produce sharp and clear image.
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It is contained in a Capsule. The old cell dies and they are trapped in the Capsule. These cells get together to form the cloud in the Eye. This makes the image blur.
The Cataract mostly occurs due to the aging process.
The diseases like Diabetes can also cause Cataract and the use of Alcohol may lead to the Cataract.