Understanding Cataracts & their Effects

A cataract is a clouding of the lens in your eye,1 which affects your vision and makes it difficult to do day-to-day things like reading a book or driving a car.2

Cataracts usually develop slowly and don't disturb your vision immediately, but over time your eyesight will become cloudy.2

Cataracts can affect part of the lens or all of it,3 and can occur in one or both of your eyes.1

The cloudy or misty vision caused by cataracts can eventually lead to blindness.4 However, cataracts can be successfully treated with surgery.1,2

What causes cataracts?

Cataracts usually develop because of changes in the lens of your eye, which can be caused by normal ageing or by an injury.2


Cataracts are very common and affect up to half of the population over the age of 60.3 Age-related cataracts are likely to occur (at least to some degree) in nearly all adults over the age of 65.3

There are other factors that can increase your risk of getting cataracts – including genetic disorders, medical conditions like diabetes and certain long-term medications.2

Click here to read the full list of risk factors that can cause cataracts.

What happens when a cataract forms?

Adapted from Shutterstock. ID:1013258719.

The lens in your eye focuses light onto the light-sensitive membrane at the back of your eye (the retina) to produce clear images.2

As you get older, the lens becomes thicker and less flexible. The tissues in the lens start to break down and clump together, causing cloudy (less transparent) patches.2 This clouding becomes bigger and denser over time.2

Adapted from Shutterstock. ID:1303217239.

The clouding (cataract) prevents light from passing properly through your lens. This stops a clearly defined image from reaching the retina, making your vision unclear.2

Cataracts usually affect both eyes, but one may be more advanced than the other, causing different levels of clouding in each eye.2

Cataract Symptoms

Cataracts don’t cause any pain or redness in your eyes,3 but they do cause changes to your vision.2

Symptoms may include:2

  • Clouded or blurry vision
  • Cloudy areas that start small and slowly grow larger
  • Sensitivity to light
  • Difficulty seeing at night
  • Seeing ‘halos’ around lights
  • Colours looking faded or yellowish
  • Double vision in one eye
  • Needing to change your prescription (glasses or contact lenses) often

If you start to notice these symptoms (or any other changes in your vision), make an appointment for an eye exam as soon as possible.2

Different Types of Cataracts

These are the most common cataract types and their symptoms:

Nuclear cataract: Affects the centre of the lens2

You may start to notice near-sightedness (difficulty seeing objects far away), followed by cloudy vision that may start to look yellow or even brown.2

Cortical cataract: Affects the edges of the lens2

Cortical cataracts cause cloudy areas in the shape of streaks or wedges, which start on the outer edge of your lens and slowly progress toward the centre, where they will interfere with the light entering your eye and cause cloudy vision.2

Posterior subcapsular cataract: Affects the back of the lens2

This type of cataract usually starts forming right in the path of light entering the lens, and progresses faster than other types.2 It can interfere with your reading vision and cause you to see bright halos (glare) around lights at night.2

Adapted from Shutterstock. ID:670910656.

Congenital cataract: Affects the lens during childhood2

Sometimes cataracts develop during childhood and some babies are even born with them.2 Around 50% of these congenital cataracts are genetic,4 although they may also be caused by certain health conditions or trauma in the uterus.2 Congenital cataracts don't always interfere with vision, but if they do they can be surgically removed.2

Find out more about cataract treatments and surgery here.

Understanding cataracts and their effects

What does a cataract look like?

How are cataracts treated?

Am I at risk of cataracts?

Patient stories

Patient resources


Understanding cataracts and their effects

How are cataracts treated?

Patient stories


What does a cataract look like?

Am I at risk of cataracts?

Patient resources

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