Cataracts occur when the lens of an eye becomes milky and less clear. The lens becomes more translucent than transparent, resulting in misty or blurred vision. The lens of the eye is a crystalline film that sits behind the pupil. When the light reaches the eye, it goes through the cornea and into the lens, which then focuses the light on the retina. When a person suffers from cataracts, the light is not properly focused onto the retina, making it difficult to see clearly.

A person with cataracts might suffer from double vision, see a halo around bright lights, and notice that colors have become less bold or clear.

Typically, cataracts will develop naturally as a person gets older. Cataracts stop some light reaching the back of the eye, meaning a person will need to wear eyeglasses. Cataracts slowly get worse over time, and in severe cases, surgery will be required to remove and then replace the lens itself.