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Author: Psychobabble6

Oct 23rd 2011 at 5:29:43 PM

Myopia (near-sightedness) is a more common birth defect than hyperopia (far-sightedness). When people's eyes deteriorate as they age, they become more and more far-sighted. This is why younger people with glasses generally are myopic and why hyperopic glasses for older people can just be bought off-the-shelf. Far-sightedness in youth is generally pretty rare.

The third way vision can be impaired, in addition to near-sightedness and far-sightedness, is astigmatism, which is basically when the eye is physically the wrong shape.

I also really think that blindness itself shouldn't be included here. It's really a different thing altogether.

In addition to the concavity and convexity mentioned above, the old fry-ants-on-the-sidewalk trick ''cannot'' be done with myopic lenses - the sort of lenses that most children have - as concave lenses will create a sort of halo around the shadow of the lens. This can be done, however, with hyperopic lenses as they are essentially just magnifying glasses.

Sorry for the obnoxious terminology. It's easier to type than far-sighted and near-sighted.