Contact lenses can correct your vision in the same fashion as eyeglasses. In order to focus light onto your retina properly, they change the direction that light rays. Nearsighted people may find that light rays are too focused within their eyes. Instead of focusing directly on the retina, they create a focal point in front of it. Nearsightedness can be corrected with contact lenses or eyeglasses. This is done by diverging lightrays which decreases the eye’s ability to focus. This causes the eye to move its focus point backwards, onto the retina. If your eyes are not focusing well, you may have poor vision. This is because light rays do not reach the retina at the right focus point. Contact lenses and glasses correct for farsightedness. By converging light, contact lenses and glasses increase the eye’s focus power. This causes the eye to focus forward on the retina.
Diopters (D), are the units used to describe eyeglass and contact lens power. Lens powers for correcting nearsightedness begin by a (-), whereas lenses powers for correcting farsightedness start at a (+).. Why are contact lenses thinner than eyeglasses? Why are contact lens important? It is because contact lenses are placed directly on the cornea, and not a little more than a half-inch (12 mm) away from it like eyeglasses. Because contact lenses are close to the eye’s surface, the opticzone of them can be reduced in size. The optic circle of contact lenses only covers a small area of the lens. Peripheral fitting curves do not affect your vision. It is like looking through a small window in your living room. But if your window is far away, your view will be limited. Because contact lenses rest directly against the cornea, your optic zone should be roughly equal to the diameter of the pupil (about 9 millimeters) in low-light conditions. Eyeglass lenses typically measure 46 mm in size to ensure a clear field of vision. Contact lenses are smaller in size so eyeglass lens are larger.
To avoid contact lenses breaking, eyeglass lens must be thicker that contact lenses. For eyeglasses with nearsightedness, the minimum center thickness must be 1.0 mm to comply with impact resistance guidelines. Contact lenses may be thinner. Nearsightedness soft contact lenses have a minimum center thickness of 0.1mm. Contact lenses are thinnest than eyeglasses because of their combination of a significant difference in wearing position, optic circle diameter and minimal thickness.
