What is a cataract?

A cataract is a lens that has become cloudy due to age, certain medications or medical conditions.

The natural lens in the eye is transparent when we are young, allowing the eye to see clearly through it and focus on different distances. Over the years the lens becomes more cloudy due to a change in the lens proteins. This change is usually gradual, although some types of cataract can develop quickly.

Risk factors that may speed up the development of a cataract include:

  • Ultraviolet exposure
  • Diabetes
  • Smoking
  • Steroids
  • Trauma to the eye


Most cataracts develop slowly and the symptoms develop gradually, although some types of cataracts (posterior subcapsular, in particular) can develop quite quickly. In the early stages, the symptoms may be very minimal and a person may not even be aware of a cataract.

As the cataract progresses, the following symptoms become more apparent:

  • Blurry vision
  • Hazy vision
  • Sensitivity to light and glare
  • Reduced night vision and difficulty driving
  • Difficulty seeing the street signs at a distance
  • Difficulty recognising people as they walk towards you
  • Reduced brightness