the lenses used for near sighted people are cancave lenses so that the image forms farther back on the retina and for far sighted people, a convex lens is used to make the image fall right on the retina!! =D XD
hope this helped!! :)
A patient with nearsightedness will usually need minus lenses to see clearly in the distance. If you have just received an eye examination and seen your doctor quickly scribble a bunch of numbers onto a prescription pad, you may have been curious to know what type of lenses he or she prescribed and the reasoning behind it.
A person with nearsightedness has a eye condition known as myopia. A myopic prescription will have a minus sign in front of the first three digits on your prescription. An example would be -3.50. The higher the number after the minus sign the worse your vision will be at viewing objects at a distance. The units after the -3.50 are known as diopters which measure your refractive condition.Lenses are mostly common placed into a eyeglasses frame to wear when viewing objects at a distance. What you will notice about a minus lens is that the edges of the lens will be thicker than the center part of the lens. This is so that light can be refracted, or redirected, further back onto the retina. Myopic individuals have eyeballs that are too long for where light naturally falls onto the retina. Minus lenses help to focus light further back in order to reach the retina. Unfortunately, the higher the degree of myopia the increased risk for eye diseases such as macular degeneration and retinal detachments.
Eyeglasses are not the only method of treating myopia. Patients with myopia can also be treated with contact lenses, corneal reshaping, and refractive eye surgery. Contact lenses can be hard or soft lenses that have similar properties to glasses except that they are placed directly onto the eye. Patient will wear them during the day as needed and remove them before going to bed. Corneal reshaping involves a molding retainer that will flatten the cornea to correct for myopia. These retainers are worn only while asleep and are ideal for children who are getting more nearsighted as they age. Lastly, refractive surgery involves a laser that can reshape the curvature of the cornea to eliminate symptoms of myopia.
Near Sighted. If you need glasses if you cant see close up, you are far sighted. You need the glasses to see close up, so your not near sighted.
A person who is farsighted needs a converging lens, which is a convex lens, to help focus light properly onto the retina. This type of lens helps to converge incoming light rays so that distant objects can be seen more clearly.
I need my glasses for driving because I am too near-sighted to read the traffic signs.
you need big round ones like c boyce
Hyperopic, plus powered, or convex lenses.
Near sightedness or Myopia is mainly caused by the eye being too long, rays of light focus in front of the retina.Far sightedness or Hyperopia is mainly caused by the eye being too short, rays of light focus behind the retina.Lots of children are born with Hyperopia but "grow out" of it because as they, grow, the eye lengthens.That is why more people are near sighted, you can't "grow out" of it.AnswerYour eyes have to be perfectly round to have perfect vision. the real question is why so many people don't need glasses?
Yes, it is possible to have astigmatism in one eye. Astigmatism is a common refractive error that occurs when the cornea or lens of the eye is irregularly shaped, causing blurred vision. This irregularity can affect one or both eyes.
Now when they remove the cloudy lenses in Cataract Surgery they replace them with plastic lenses focused for far vision, so you will need glasses for near vision. Many people get bifocals with no prescription for the main lens part and the near vision prescription for the bifocal part. Other people just carry prescription near vision glasses for when they need to look at things close up but normally wear no glasses at all.Years ago (before they began putting in plastic lenses) everyone needed glasses all the time after having Cataract Surgery, because there was no longer any lens in the eye to focus the light.
Lenses can correct vision problems by bending light rays before they reach the eye, in effect moving the focal point of the eye's lens so that it falls upon the retina and creates a clear image. Concave lenses cause light rays to converge and lengthen the focal point for the near sighted eye. Concave lenses are thinner in the middle and thicker on the edges and may be curved on one or both sides. Concave lenses cause light rays to diverge, or spread apart. :)
the affect is that the length of the eye is too long and that causes it to affect the way you can see
That condition is called presbyopia, where the eye loses its ability to focus on close-up objects due to the natural aging process. It typically occurs around age 40 and is a common condition that can be corrected with reading glasses or multifocal lenses.
You may need to adjust the focus of the lens or clean the lens to improve the clarity of the image. If the issue persists, you may need to check for any scratches or damage on the lens that could be causing the blur.