There are many causes to cataracts, of which the most common is age. Cataracts are a part of the normal aging process and are most often found in those over the age of 60. When the proteins in the lens of the eye are disrupted and break down, it causes the lens to become cloudy leading to a cataract. 

Other causes of cataracts include UV damage, trauma, systemic conditions, certain medications, and congenital conditions. Prolonged UV light damage from not wearing sunglasses while being outdoors is a common cause of cataracts. Trauma to the eye including injuries, surgeries or radiation treatments can cause cataracts. Systemic conditions such as diabetes can cause cataracts as a buildup of sorbitol results in cloudiness of the lens. Individuals with diabetes should keep tight blood sugar control. Other systemic conditions that can cause cataracts include hypertension, obesity, chronic kidney disease, and autoimmune disease. Certain medications can cause cataracts to develop early, such as corticosteroids, chlorpromazine, amiodarone, phenytoin. In some cases, people are born with cataracts. These are called congenital cataracts. They may be inherited or result from an underlying health condition.