What causes a cataract?

In some cases, genetic disorders or conditions can contribute to the development of cataracts. However, oftentimes cataracts form as people age without a specific cause. Factors such as eye injuries, long-term exposure to the sun, smoking, and certain medications may all play a role in the formation of cataracts.

The most common type of cataract is related to aging of the eye. Other causes of cataract include:

  • Family history
  • Medical problems, such as diabetes
  • Injury to the eye
  • Medications, especially steroids
  • Radiation
  • Long-term, unprotected exposure to sunlight
  • Previous eye surgery
  • Unknown factors
Sreedhar Potarazu

Cataract is an aged related change to the natural lens of the eye that happens in almost everyone. The increased opacity of the lens can cause vision intitally to be blurred and hazy. One may intially notice seeing haloes around bright lights or glare at night from oncoming headlights as an intial sign. There are some studies to sugest that catracts are are caused by excessive sun exposure and are thus more common in populations who live closer to the equator. Cataracts are treated only when one cannot perform their daily routine because of vision impairment. The treatment of cataract is surgical removal; of the lens with the placement of a lens implant.

Laura C. Fine, MD
Contrary to what some people believe, cataract (clouding of the normally clear lens of the eye) is not caused by a film blanketing the eye, nor is it related to overuse of the eyes. It does not spread from one eye to the other -- although the condition may develop in both eyes.

Aging and accompanying changes in the chemical composition of the lens are the most common causes. Many cataracts develop as an exaggeration of normal aging sclerosis, in which the lens becomes less resilient, less transparent, and often thicker. Fibers in the lens become compressed, and the lens becomes more rigid. Clarity fades as proteins coagulate, or clump together, creating tiny specks or wheel-like spokes in the periphery of the lens. In later stages, the milkiness becomes denser and occurs in the center, making it truly difficult to see. The change in the lens is similar to what happens when you cook an egg white; it goes from clear to opaque. Early on, before cataracts blur vision, they can cause nearsightedness, double vision, or distorted vision.

Although age is the factor most likely to cause cataract, other factors such as family history, eye injuries, use of some medications (particularly corticosteroids), and certain health problems (such as diabetes) can contribute to cataract as well. Several studies have linked cataract with alcohol consumption and smoking. Even if you have smoked for many years, quitting now will help lower the chances of cataracts forming in the future. Long-term exposure to high levels of ultraviolet-B (UVB) rays from the sun is another hazard, and studies have found a greater prevalence of cataract in people who live in areas with considerable sunlight. Wearing sunglasses can help protect eyesight and minimize cataract formation.
Michael T. Murray, ND
Naturopathic Medicine

Aging-related (senile) cataracts form when the normal protective mechanisms of the eye are unable to prevent free-radical damage. The lens, like many other tissues of the body, depends on adequate levels and activities of antioxidant nutrients and enzymes for its normal protective mechanisms. When it is either overwhelmed by the demand for or deficient in the supply of antioxidant nutrient and enzymes, cataracts form. For example, exposure to cigarette smoke or sunlight increases the risk of cataracts by creating an increased need for antioxidant nutrients and enzymes in the lens of the eye.

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Kelly Traver
Internal Medicine

Cataracts occur due to a change in the chemical composition of the eye's lens, which causes the lens to become cloudy. This condition occurs in most people who live past 70, but frequent exposure to direct sunlight seems to accelerate the process. This condition can easily be treated with surgery to remove and replace the lens.

Cataracts, a clouding of the lens inside the eye, have multiple causes. Aging is the most common, as the proteins that make up the lens slowly degrade over time. Radiation, such as UV light, microwaves and X-rays, can also cause or contribute to cataracts. Blunt trauma can cause cataracts when the inflammation, swelling and whitening that can happen does not completely resolve. Cataracts are also associated with a number of genetic, metabolic/nutrition and skin diseases. Smoking appears to increase the risk of cataracts. Medications and iodine deficiency can cause cataracts. Some infections, such as varicella and toxoplasmosis or even congenital infections (infections of fetuses before they are born such as rubella or syphilis), can cause cataracts too.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.