How does eyeglasses correct both nearsighted and farsighted eye problems?

by David Jenyns

Question by TheNewEra: How does eyeglasses correct both nearsighted and farsighted eye problems?
I need to understand how, eyeglasses fix these two eye problems. How do eyeglasses combine with the light path? How does it reflect or refract light? If you’re an expert at this, please help me understand. 10 points for the best answer.
Thank you (:

Best answer:

Answer by i?u
It basically “directs” the light to the retina so the eye can focus on the objects. In far-sighted people’s eyes the light reaches behind the retina, and in short-sighted it doesn’t reach the retina. So, basically, glasses help where the light reaches.

What do you think? Answer below!

{ 1 comment… read it below or add one }

Footprintz April 1, 2011 at 7:31 am

It’s the precise curvatures of the lenses that will determine the way it will bend light rays to make them focus directly on the retina.

A concave lens ( minus powers ) lengthens the light ray to correct nearsightedness because the eye is too long, and a convex lens shortens it because the eye is too short ( plus powers ) in the case of farsighted people. Farsighted people also require glasses for distance vision.

Then there are people who need reading glasses because the lens of the eye doesn’t accommodate enough anymore for close vision ( the over 40 crowd ).. Accommodation is when the lens of the eye gets thicker or thinner to change the focusing power of the eye. Convex lenses are used to provide extra magnification in those cases. Those people have presbyopia and use plus powers like a farsighted person does, but only for near.

Although some people need a concave lens ( minus power) as reading glasses if they are quite nearsighted to begin with when presbyopia starts. They require a lens with less minus power than they need for distance vision.

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