How does eyeglasses correct both nearsighted and farsighted eye problems?
TheNewEra asked:
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 (:
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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 (:
July 5th, 2010 at 1:26 pm
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. i♥u
July 6th, 2010 at 11:01 pm
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. Footprintz