Short sight occurs when light is focused in front of the retina causing distance vision to become blurred. Near vision, however, is usually clear. Short sight normally develops in childhood or adolescence and is often first noticed at school. Glasses may need to be worn all the time or just for driving, watching TV or sports.
Long sight occurs when light is focused behind the retina rather than on it, and the eye has to make a compensating effort to re-focus. This can cause discomfort, headaches or problems with near vision. Glasses may need to be worn all the time or just for close work, such as reading, writing or computer use. In older people, as re-focusing becomes more difficult, distance vision may also become blurred.
Astigmatism occurs when the curvature of the cornea or lens is not perfectly round. It is sometimes described as the eye being shaped like a rugby ball rather than a football. Most people have a small amount of astigmatism, which may not need correcting. If vision is blurred or headaches occur, your optometrist may recommend glasses are worn all the time or just for specific tasks.
Presbyopia is the loss of focusing ability that occurs naturally with age. In younger people, the lens is very flexible and the eye has a wide range of focus from far distance to close up. As you get older, the lens slowly loses its flexibility leading to a gradual decline in ability to focus on near objects. Presbyopia is not a disease but a normal and expected change which sooner or later affects everyone, whether you already wear glasses or contact lenses or not. Around the age of 40-45, you will begin to notice that you are holding the newspaper further away or need more light to read small print. There is no advantage in delaying using reading glasses, or changing to bifocals or varifocals. They will not make the eyes lazy. Your optometrist will advise you on the best form of vision correction to suit your individual lifestyle and occupation.
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