EDP column by Dr Ketan Dhatariya

“I have noticed some deterioration in my vision. My optician tells me I have a cataract. What is this?"

The eye is designed to focus light onto a very small area on the back of the eye. To do this, the eye has 2 structures that help to focus the light. The first structure is the cornea – the clear part of the eye that lies on top of the iris (the coloured part of the eye). The light then passes through the second structure – the lens. This helps to focus the light very specifically onto the specialist part of the back of the eye designed to see colours. A cataract is an opacity in the lens. This opacity occurs over many years and can very slowly affect vision.

There are a number of conditions that can occur during pregnancy that may predispose a baby to develop cataracts, but when a child is born, and at regular intervals, your doctor will look into the baby’s eyes with an ophthalmoscope (even from a distance) and be able to tell if there are cataracts there. You may have done this yourself - if you imagine a photograph taken with a flash – if you can see the red in the eyes - that shows that there is unlikely to be a cataract there. This is known as a ‘red reflex’. 

Other than ageing, there are a variety of reasons why cataracts may develop. These include exposure to long-term ultraviolet light or other forms of radiation. Certain conditions such as long term poorly controlled diabetes may accelerate the development of cataracts. Occasionally, certain medicines may also lead to the development of cataracts.

Symptoms to be aware of, other than a progressive loss of vision, include dazzle/glare - this especially may occur when driving at night, light scattered by the cataract producing multiple images or frequent spectacle changes. Your doctor will consider lots of things before they refer you to an ophthalmologist. These include your level of visual function and quality of life, as well as your willingness to have surgery. Surgery is usually necessary when the cataract is severe enough to impair your everyday life.

Cataracts are one of the leading causes of blindness in the world, which seems a pity because they are very easily treatable by a relatively straightforward operation done under local anaesthetic. There are lots of charities that carry out these operations in poor countries across the world that you can donate to.

For more information about Cataracts click this link: