Most people’s eyes are round like a football and light focusses on one area of the retina (the thin layer of tissue that lines the back of the eye). If you have astigmatism your eye is shaped a bit like a rugby ball. This means that the light focusses on more than one area of the retina so your vision is distorted (you may find it difficult to tell ‘N’ from ‘H’, for instance) or blurry.
Astigmatism can cause blurred vision, headaches and eyestrain (you may notice this after concentrating for a long time – on a computer, for example). Astigmatism normally occurs alongside short sight or long sight.
Astigmatism is a type of refractive error, and is corrected with glasses, or contact lenses to enable you to see clearly. If your astigmatism changes, or you are having it corrected for the first time, you may find your glasses feel strange at first, whilst your brain gets used to seeing things with the astigmatism corrected.