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Causes of Astigmatism

To focus images, your eye has two parts – the cornea and the lens. When the cornea in the front-part of your eye and the lens inside the eye are a regular symmetrical ball shape, all incoming light is sent the same way to make a sharply focused image in the back of your eye. 

Astigmatism occurs when the cornea or lens are shaped more like a rugby ball – longer in one direction than the other. This means that the image at the back of your eye isn’t as sharply focused. Corneal astigmatism is when the cornea is a distorted shape and lenticular astigmatism occurs when the lens is distorted.

In most cases, astigmatism is present at birth as the size and shape of the eye is developed in the womb. It may be due to environmental and genetic factors but the exact cause isn’t known. Sometimes astigmatism can develop after an eye injury, surgery or eye disease. 

Astigmatism is not caused by factors such as reading in poor light, constant squinting or watching too much television.

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