Optical discrepancies between the various components of the eye cause a majority of the human population to have some form of refractive error. People who are unable to bring distant objects into clear focus are nearsighted, or myopic. Myopia can be caused by the front of the cornea being too curved or the eyeball being too long. In either case, with the lens as flat as it can be, the image of distant objects focuses in front of, rather than on, the retina.

Neuroscience, Sinaur Associates (QP355.2.N487 1997)

Perhaps you had idly noticed that a lot of people need glasses these days. Maybe some of you have even wondered what we all did before glasses were invented. A few of those might have even considered the possibility that we didn't need glasses, as a people, until recently.

According to a 1995 Cornell University study, "Nearsightedness now affects from 20 percent of some populations to 80 percent of others in the United States and Europe, and up to 90 percent in Far East countries."

There are two prevailing theories for this:

  • Environmental: all the "near work" we do in modern society (reading, computers, time spent inside buildings, etc) has adverse effects on eye development.
  • Genetic: corrective lenses, which conclusively date back approximately 700 years, have kicked the natural selection-driven evolution process into reverse for eyesight, and 20/20 vision happened to be a recessive trait.

My*o"pi*a (?), n. [NL. See Myope.] Med.

Nearsightedness; shortsightedness; a condition of the eye in which the rays from distant object are brought to a focus before they reach the retina, and hence form an indistinct image; while the rays from very near objects are normally converged so as to produce a distinct image. It is corrected by the use of a concave lens.

 

© Webster 1913.

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