Myopia; Shortsightedness; Refractive error - nearsightedness
There is no way to prevent nearsightedness. Reading and watching television do not cause nearsightedness. In the past, dilating eye drops were proposed as a treatment to slow the development of nearsightedness in children, but they have never been proven effective.
The use of glasses or contact lenses does not affect the normal progression of myopia -- they simply focus the light so the nearsighted person can see distant objects clearly. Hard contact lenses will sometimes hide the progression of nearsightedness, but vision will still get worse "under" the contact lens.
Olitsky SE, Hug D, Smith LP. Abnormalities of refraction and accommodation. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 619.
Wilkinson PS, David EA, Hardten DR. LASIK. In: Yanoff M, Duker JS, eds. Ophthalmology. 3rd ed. St. Louis, Mo: Mosby Elsevier; 2008:chap 3.5.