Certainly, Gary, try:

http://www.preventmyopia.org/animation.html

Best,

Otis

++++++++

Otis didn't answer the question you asked. You asked the effect of
_correcting_ myopia, hyperopia and astigmatism.

Correcting these conditions with spectacle lenses produces minification
(nearsighted glasses) and magnification (farsighted glasses) and a related
nonlinear effect called barrel or pincushion distortion. I don't recall an
illustration with glasses only. You can probably google "pincushion barrel"
and see diagrams of those conditions.

With low prescriptions, these effects are pretty minimal.

If you meant to ask the effect of _being_ farsighted or nearsighted, you can
try someone else's glasses to get an idea.

If you wear a nearsighted person's glasses you'll see what farsightedness is
like.

If you wear a farsighted person's glasses (or drugstore reading glasses) you
see what nearsightedness is like.

If you wear glasses made for someone with substantial astigmatism, those
lenses will create astigmatism in an individual who doesn't have any (only
while they're worn... it doesn't change the eye.)

-MT

Dear Gary,

The intent of your question is not clear.

If you have normal 20/20 vision (refractive state from zero to +1
diopters),
then you can SIMULATE 3 diopters of myopia by simply wearing
a +3 diopter lens.  That is the level of "blur" a -3 diopter myope will
see in the distance, as well as the approximate "blur" on his Snellen.

If you have a refractive state of zero (and 20/20) and wish to simulate
a refractive state of +6 diopters, then the APPROXIMATE method
would be to get a -6 diopter lens -- and wear it.  If the person is
young, however, his accommodation enable him to see through
the +6 diopters.

To simulate astigmatism (assuming you have none), then
just get a cylender lens of -2 diotpters, and wear it.
If you have a trial-frame, you can rotate the lens through
an angle from zero to 180 degrees.

Hope this helps clarify these issues for you.

Best,

Otis