Concave lenses are used in eyeglasses that correct nearsightedness. Because the distance between the eye's lens and retina in nearsighted people is longer than it should be, such people are unable to make out distant objects clearly. Placing concave lenses in front of a nearsighted eye reduces the refraction of light and lengthens the focal length so that the image is formed on the retina. Convex lenses are used in eyeglasses for correcting farsightedness, where the distance between the eye's lens and retina is too short, as a result of which the focal point lies behind the retina. Eyeglasses with convex lenses increase refraction, and accordingly reduce the focal length.
Whether your eyes are still in good condition or whether you are already wearing eye glasses you can maintain or improve your eyesight by exercising your eyes everyday.
You can do it by rotating your eyeballs through the perimeter of your eyes by looking around you surrounding from left then up and to your right and down. Look as far left or right or up or down as much as you can. In this way you are developing eye muscles which could then control the curve of your eyes' lense. This exercise is also believed to prevent catarac.
If you need glasses see to it that you've got the best both in quality and price. Don't go for anything less. Go for ZenniOptical.com and you will get the best value for your money.
No comments:
Post a Comment