In the normal eye, light passes through the cornea, the clear front window of the eye, and focuses the image precisely through the lens onto the retina, a layer of light sensitive cells that line the back of the eye. When the image projected onto the retina is not focused you have what is called a refractive error. Objects at a distance appear blurry. Myopia is hereditary and if your family has a history of nearsightedness then it is likely that your children will have myopia too. Other things, such as reading in low light, poor eating habits, or strain on the eyes do not cause or affect myopia.
Close objects appear blurry and are difficult to read.
Normally, all young children have a small degree of hyperopia that decreases as they get older into their teenage years. Despite having a small degree of hyperopia, young people who are farsighted can see well for both near and far away objects because the focusing ability of the lens is enough to correct vision. Like myopia, hyperopia is inherited. In children, headaches and lack of interest in reading may be a sign of severe hyperopia. Most children will not need glasses or contact lenses for hyperopia, but some with severe degrees of hyperopia or crossed eyes caused by severe hyperopia may.