The main causes of cataracts in humans are injuries to the eye and aging, according to Mayo Clinic. Some people have genetic or medical conditions that make them more susceptible to cataracts. Diabetes is one disease that increases the risk of cataracts. Some babies may be born with cataracts if their mothers caught an infection while pregnant, says Mayo Clinic.
The lens of the eye is found behind the iris. It is supposed to be crystal clear to focus the light that passes through it to the retina, which is found at the very back of the eyeball. As a person ages, the lenses become more rigid and begin to deteriorate. These deteriorated bits of the lens begin to stick together and cloud areas inside the lens. Eventually, the whole lens may be clouded. Cataracts are progressive and grow denser over time. They may even turn yellow or brown with age and affect a person's perception of color. Cataracts can involve one or both eyes, but at different rates.
Cataracts can only be removed through surgery, according to Mayo Clinic. Still, the patient and the doctor should confer as to when the surgery should be considered. Though cataract surgery has improved greatly over the years, it still carries risks, and cataracts don't really affect the health of the eye.