A cataract is a cloudy or opaque area in the eye’s normally clear lens. It can obstruct normal vision depending on its size and location. Cataracts are most common in people over the age of 55, but they can also occur in infants and young children, as a result of trauma or medications. Cataracts usually develop in both eyes, but one may be worse than the other.

The lens is located behind the iris, the colored part of the eye, inside the eye. Normally, the lens focuses light on the retina, which sends the image to the brain via the optic nerve. However, when the lens is clouded by a cataract, light is scattered and the lens is unable to focus properly, resulting in vision problems. The lens is mostly made of proteins and water. The clouding of the lens is caused by changes in the proteins and fibers of the lens.

3 Types of Cataracts

The lens is made up of layers, much like an onion. The capsule is at the very top. The cortex is the layer inside the capsule, and the nucleus is the layer on the inside. A cataract can form in any of these locations. Cataracts are named after where they are in the lens:

  • A nuclear cataract is a cataract that is located in the center of the lens. The nucleus darkens with age, changing from clear to yellow and occasionally brown.
  • The layer of the lens surrounding the nucleus is affected by a cortical cataract. The cataract resembles a wedge or a spoke.
  • A posterior capsular cataract is found in the lens’s back outer layer. This type frequently develops more quickly.

Risk Factors

The majority of cataracts are caused by age-related changes in the eye’s lens, which cause it to become cloudy or opaque. Other factors, however, can contribute to cataract development, such as:

  • Diabetes mellitis is a type of diabetes. Diabetics are more likely to develop cataracts.
  • Drugs. Certain medications have been linked to the development of cataracts. These are some examples:
    • corticosteroids.
    • Other phenothiazine-related medications include chlorpromazine.
  • Ultraviolet light. Unprotected exposure to ultraviolet (UV) radiation has been linked to an increased risk of cataract formation, according to research.
  • Smoking. There may be a link between smoking and increased lens cloudiness.
  • Alcohol. Several studies have found that patients who consume more alcohol have more cataracts than those who consume less or no alcohol.
  • Deficiency in nutrients. Despite inconclusive findings, studies suggest a link between cataract formation and low levels of antioxidants (such as vitamin C, vitamin E, and carotenoids). Further research may reveal that antioxidants can aid in the prevention of cataract development.
  • History of the Family. If a close relative has had cataracts, you are more likely to develop one yourself.

Cataracts are rarely present at birth or develop soon after. They can be inherited or develop as a result of a maternal infection (such as rubella) during pregnancy. A cataract can also develop as a result of an eye injury or surgery for another eye condition, such as glaucoma.


Cataracts typically form slowly. Cataract signs and symptoms may include:

  • Vision that is blurry or hazy.
  • Color intensity has been reduced.
  • Increased sensitivity to light glare, especially when driving at night.
  • Night vision has become more difficult.
  • Change in the refractive error of the eye, also known as eyeglass prescription.

Learn more about cataracts diagnosis and treatment next week!

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Source: American Optometric Association

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