Myopia (short-sightedness) is a leading cause of loss of vision throughout the world, and is on the increase.

When a child is born, s/he does not see in focus. The ability to focus tightly according to the distance of the object viewed develops right through to age 4-5, by which time most people focus well. Arguably, except in severe cases, interfering before this time by giving children glasses may not be productive. Some people never develop the ability to focus well across the full range of distances, becoming naturally short or longsighted, requiring corrective glasses or contact lenses.

Most researchers agree that myopia is largely genetic, but can also be caused by lifestyle. Research suggests that prolonged reading, or the retinal blur caused by prolonged near work, are principal causes, thus confirming the warnings against reading in the dark, in a moving car, or holding the book too close. Furthermore, people whose professions entail a lot of reading during either training or the performance of their occupation (lawyers, physicians, microscopists, and editors) have higher rates of myopia. Myopia is almost unknown in aboriginal peoples but, when they adopt book-based Western education methods, rates quickly rise to those in more industrially developed countries.

Myopia can develop not just in early life, but throughout peoples' 20s and 30s. Whilst acknowledging and wishing to promote the joy of reading, Douglas Frederick advises that people can reduce their risk of becoming myopic by ensuring adequate light and a healthy element of physical activity in their lives.

Ed.- (i) One implication is that children should not be encouraged to read books up close before age 5-6.

(ii) Myopia is almost unknown in aboriginal peoples but, when they adopt book-based Western education methods, rates quickly rise to those in more industrially developed countries.