When you don’t have perfect vision, it’s not considered a life threatening or even life altering condition. It just means you need a pair of prescription glasses. It is remarkable how this deceptively simple looking product works so well at restoring one of the most important of your five senses. If only other problems could be remedied so easily. How do prescription glasses work? To answer this, you need to understand how vision works.
How Vision Works
When light reflects off an object, it scatters in all directions. Even the reflected light from a single point on the object scatters in the same way. If this reflected light hit a photographic film, you wouldn’t see a photograph of the object because the scattered light from every point on the object’s surface is spread out and “smeared” across the film. However, if you place a lens at the right distance between the object and the photographic film, scattered light from each point of the object is brought back together (focused) on the film and forms an image. You would also have to block out extraneous light.
The eye works in a similar way. Scattered light from an object goes through the lens of the eye, which focuses the light and forms an image on the back surface of the eye, called the retina. The retina then sends signals of the image to the brain.
How does a lens focus light? The light passing through a convex lens, which is thick at the center and thin at the edge, always bends light rays together so that they come together at a focal point. A concave lens (thin at the center and thick at the edge) does the opposite and bends light rays outward.
How Nike Prescription Glasses Correct Farsighted Vision
Unlike fixed glass or plastic lenses, the lens of your eye can change its shape so that it can focus light on the retina for objects at different distances. However, the lens of a person with farsightedness can’t focus light from close-up objects on the retina because the retina is too close to the lens.
This is caused by an eyeball that’s too short. The lens focal point for the eye with farsighted vision is somewhere behind the retina. The light rays need to be bent closer together to bring the focal point back to the retina. As mention previously, convex lenses do precisely this. Therefore, glasses with convex lenses are prescribed to farsighted people. The strength for convex lenses is given in plus (+) diopters.
How Nike Prescription Glasses Correct Nearsighted Vision
The nearsighted person has the opposite problem. This person’s lens can’t focus light from faraway objects on the retina because the retina is too far away from the lens. In this case, the eyeball is too long, and the light rays converge (focus) before they reach the retina.
This problem can be corrected by spreading out the light rays just enough so that they focus on the retina. Placing a concave lens in front of the eye’s lens will have this effect. Therefore, glasses with concave lenses are prescribed to nearsighted people. The strength for concave lenses is given in minus (-) diopters.
How Nike Prescription Glasses Correct Astigmatism
The cornea or lens of people with astigmatism aren’t evenly curved in all directions as they should. The curve is more oval than rounded, which means the cornea or the lens is football shaped. This causes distorted or blurred vision for near and far objects. Cylindrical lenses are commonly used to counteract the optical distortions produced by the oblong shape of the cornea or lens.
If you need eyewear, take advantage of the many options available with our Nike prescription glasses. We offer many frame styles, lens materials, colors, and coatings. For more information about our Nike prescription glasses, contact us.