Farsightedness can be corrected by using eyeglass lenses that are what?
146400
Farsightedness is corrected using a convex (thicker in the center) lens.  These types of lenses cause light entering them to converge.  \nTake a look at the images of farsighted eyes and lenses here:\nhttp://www.educ.uvic.ca/Faculty/sockenden/edb363/1999/projects/LightOptics/lenses.htm\nThey should help to clarify things.\nThis site also provides a useful summary of optics and farsightedness.\nhttp://www.glenbrook.k12.il.us/gbssci/phys/Class/refrn/u14l6d.html\nHope this is helpful :-)
276813
Soft contact lenses can now correct astigmatism.
156368
No. You may see a distorted image, but it is not what the person themselves see without glasses.\n\nI'm high-myopic, -9 to -10, and people would look through my glasses and say "wow, do you really see like that?"\n\nI'd have to tell them "no. That's the correction to my vision, not the way I see without glasses."\n\nOne day, by accident, I found common lenses that would let me show other people what my uncorrected vision was like. I picked up a double pocket magnifying glass. It had two ordinary magnifying lenses in it that could be swung out one at a time or both at once to increase magnification. With both lenses out, while I was wearing my glasses, I looked through the magnifiers at a distant wall. I realized that what I was seeing was the same as I would see without any glasses at all! \n\nSince then I've had a way to show people roughly what I see like without glasses. For extreme nearsightedness, put two standard magnifying glasses together and hold them to one eye about where normal eyeglasses would sit and look at something distant. If you're vision is in the normal range, you'll approximate my uncorrected vision.\n\nIn general, I believe, if you want to know what it is like to see what another sees *without* their glasses, and your vision is withing normal limits, you would need another pair of glasses made to the *opposite* prescription. Theirs corrects the prescribed amount, your vision would have to be distorted that same amount.\n\nMy trick wouldn't show you how someone farsighted sees. You'd need a different type of lens. In general, correction for nearsightedness like I've got is done with lenses that make distant objects smaller and darker. Correction for people with farsightedness is accomplished with lenses that are more like magnifying lenses.\n\nThis doesn't even deal with other problems with the eye, such as astigmatism or presbyopia.\n\nThere's one plus to my vision that most people don't realize -- when I take my glasses off, I see magnified up to a distance of about four inches. I can literally read engraving on the head of a pin.\n\nThen there's what Spider Robinson said: "People with glasses are lucky. We can see stars on rainy nights."
757629
It focuses an image on the retina so that you can see it.  The shape of the lens in the eye is controlled by muscles, so that the focal length can be adjusted to get sharp focus of both near and distant objects.  Errors in the shape of the lens can be corrected with eyeglasses.
208100
As one gets older the elasticity of the our eye lenses decreases and we require two sets of glasses, viz.\n1) Reading glasses- These are to see the things that are closer to the eyes clearly ( about 8 to 20 inches from the eyes.) This is the distance at which we usually hold any reading material, hence they are called the reading glasses.\n2) Distance or distant glasses- These are to see the things that are at a considerable distance from you for example an approach friend on the road can be clearly seen and identified with the help of these glases only.\n3) Binoculars and telescopes are just that. Binoculars and telescopes. The first is to see objects that are no normal eye can see due to the great distance ( Bird watching)\nTelescopes are for the astronomical observations that is they can see beyond the range of the binoculars.
756657
I believe you are asking if hard contact lenses can improve your vision beyond when they are in your eyes as opposed to if they work for vision correction.  Nothing can permanently correct your vision other than surgery.  While theoretically hard contacts can push on your eye enough to change its shape and therefore theoretically change vision, once you remove them, the eye will assume its normal shape pretty quickly.  But, it's probably not a good idea to push on ones eyeball, which is why those hard contact lenses are so rarely used these days.
64464
It's nearsightedness.  The convex lens formed by the eye's own lens and the curvature at the front of the eyeball determines the focal length.  A concave lens corrects the problem by increasing the focal length.
775725
Unfortunately it's not so simple as what foods to eat. You ear glasses because the lens of your eye does not focus light correctly on the retina. Like any other organ, the eyes will adjust to the lowest common denominator. If you put a cast on your arm, it will be much weaker when you take it off - if you don't use it, it gets weaker.\n\nThere is some research that suggests children who focus at a set distance consistently, say sitting in front of a TV that's 5 feet away for 2 hours a day for the first few years of their lives, grow up with difficulty focusing at distances other than the one they've hyper-practiced. Unfortunately this is not a proven fact, and it's findings don't exactly translate to adults who stare at computer screens, so take it with a grain of salt.\n\nWearing glasses will slightly weaken the eyes, and there is a good change your prescription will change over time. Part of this is the lens adjusting to the "crutch" of glasses, but most of it is the natural aging process called presbyopia. As you get older, your eyes are less able to focus to multiple distances - which is why most people over 40-50 wear glasses (even if just reading glasses).\n\nIf you're determined to reduce your dependence on glasses, there's always contact lenses and vision correction surger. The latter reshapes the lens of the eye to refocus the light correctly. I had this done 5 years ago and went from 20/400 and 20/500 to 20/20 and 20/25  - it was great to be able to see the alarm clock from my bed!\n\nHope that helps,\nOdd
423455
Yes, by placing a simple microscope close to the eye, the light rays which were diverging from the object are now diverging less or even convering a little before they reach the eye's lens. The far sighted observer's eye does not have to converge the light rays as much and their weaker focussing power is now sufficient to form a focussed image on the retina.
179946
Do you mean bifocals or trifocals which are worn by older people to compensate for needing to see far (nearsightedness) and having a problem reading.\n\nReading glasses only work for reading and close work like embroidery or scrapbooking. You can't read signs, clocks across the room, etc.
950953
yes, squinting can actually progress the development of nearsightedness over a period of time by changing the shape of the eye.  even though it does ''help'' by clearing up vision, it does more damage in the long run.\n\nthere are vision exercises you can do that will reduce or overcome nearsightedness.  i used to see worse than 20/200, but now i see about 20/60, and when i want to, i can achieve 20/40 and sometimes that becomes 20/20.  if you wanna know more about the exercises, hit me up at phtokhos@yahoo.com.
1182493
I don't think so.  I have terrible eyesight.  I can't even see the big\n"E" on the eye chart!  I am very nearsighted.  I am in my mid 30's and have had the same prescription for several years now.\nI think it's because I do as much reading as possible without my glasses and I don't wear contacts anymore.  My sister, on the other hand, gets a new prescription every year and it's always worse.  I have heard of some kind of eye exercises advertised on the radio that supposedly restore at least some sight.  I'm sorry I can't be more specific.
918738
http://science.howstuffworks.com/question126.htm\n\n20/20 means that at 20 feet away, the person can see what a 'normal' person can see at 20 feet.  20/40 means that at 20 feet away, the person can see what a 'normal' person can see at 40 feet.  (Paraphrased from site.)\n\nNow:  not consulting the site anymore. . . .\n\nThe eye prescription is measuring something different, and you're missing part of it.  There should be minus signs or plus signs:\n\n-0.25 + 1.50 x 134\n\nThe first number is called the cylinder.  The second number is called the sphere, and the third number is called the axis.  If the first number is negative and the second number is positive, then the glasses are for a nearsighted person.  I'm not sure what the configuration is for a farsighted person.  My guess is that your friend is farsighted(?), or at least not very nearsighted at all.\n\nYou are trying to compare apples and oranges.  You need to know how well your friend sees on the 20/20 scale, or else you need to know your own eyeglass prescription in order to see who has the stronger prescription.  An optician told me that thicker glasses do not necessarily mean your vision is worse than the vision of someone else who does not have as strong a prescription as yours.\n\nThe defiinition of legal blindness includes the phrase "best corrected vision."  Neither of you seem to be anywhere near that threshold (20/200 in the better eye, best corrected vision).  But notice that visual acuity is measured on the 20/x scale and is not expressed in terms of sphere, cylinder or axis.  \n\nBy the way, my brother told me that the measurement for glasses (-13.75+0.75x010) is taken in diopters.  So if you're wondering minus 13.75 what, it's diopters.  And that was the prescription for my right eye at one time (I'm not sure what the latest prescription is).  The right eye is the worse eye, at least.  Oh, well.\n\nhttp://en.wikipedia.org/wiki/Diopter\n\nA dioptre, or diopter, is a measurement of the optical power of a lens or curved mirror, which is equal to the reciprocal of the focal length measured in meters.\n\nAt any rate:  in order to make a fair comparison, you need to compare your prescription to your friend's prescription or your best corrected visual acuity to your friend's best corrected visual acuity.
323979
niktom_teen87 almost has it right.  It is called orthokeratology (ortho-k for short) and it doesn't permanently correct your vision.  The procedure involves specially shaped rigid contact lenses that re-shape the cornea (the front of the eye) while you sleep.  Re-shaping the cornea changes the focusing power of the eye and makes it so that the eye focuses light exactly on the retina (the back of the eye).  The reason this isn't permanent is that once you stop wearing the lenses at night, your cornea takes up its former shape, so you always have to wear a sort of "retainer" lens.  Your best bet for more specific information is to ask your eye doctor about it.  If he/she doesn't do ortho-k, he/she can at least refer you to a reputable doctor who does.
1126598
Good question.  It all has to do with changing corneal dimensions.  At some point the whole system reverses and as your cornea and lens stiffen as you age you have trouble seeing things close (farsightedness).  Thank god for glasses or we would all be crashing into each other on the highway!
162543
Is there a question somewhere there?\n\nWhen you look in a telescope you shouldn't need to wear glasses just adjust the focus till the image is clear.  The type of eyepiece you use doesn't matter.
434096
What might work better is taking them to your eye doctor or optical shop to have them adjusted.  Most places will adjust your glasses for free even if you didn't purchase them there.