Cataract

What is it?

Introduction

A dense white cataract made visible by pupil dilation.

The eye is very like a camera, and has a lens that is situated just behind the pupil. The lens is naturally transparent, allowing light to pass into the eye. 

The lens, together with the cornea, brings light to a focus on the retina and the lens can also change shape to enable the eye to focus on objects at various distances.

As we age the the lens loses both its transparency and the ability to change focus. The loss of transparency is known as cataract; the loss of ability to focus on near objects is termed presbyopia. 

By the age of 70 most adults have some cataract even if they have otherwise healthy eyes.

Causes of cataract

The most common cause of cataract is aging. Other less common causes include:

• Trauma
• Medications such as steroid tablets or eyedrops
• Diabetes

Symptoms of cataract

Common symptoms of cataract include:

• A painless blurring of vision
• Glare, or light sensitivity
• Poor night vision
• Double vision in one eye
• Needing brighter light to read
• Fading or yellowing of colours

Common myths

Many things you hear about cataracts are not true. A cataract is not:

• A growth in the eye
• A film on the surface of the eye
• Something that needs to become 'ripe' before it can be removed
• A cause of irreversible blindness