The two main functions of the lens of the eye are to focus light onto the retina and to help the eye focus on objects at various distances. The lens of the eye is a rubbery, jellylike structure. It is located behind the cornea and is held in place by tendons that are attached to a set of muscles called ciliary muscles.Continue Reading
The tendons and ciliary muscles help the eye to focus by either relaxing or pulling the lens, allowing it to become either more spherical or flatter in shape. This adjustment in the shape of the lens permits the eye to focus on objects at various distances. The adjustment occurs very quickly, allowing the eye to focus on a nearby object at one moment and a far-away object at the next moment.
Sometimes the lens of the eye does not function properly or needs extra assistance to focus on objects correctly. Eyeglasses or contact lenses provide this assistance. The lens of the eye may also become cloudy with age, which is a condition known as a cataract. Lens replacement surgery is available for people with cataracts. The lens of the eye may also deteriorate with age, and its ability to adjust from a distant to a near focus declines. Many older individuals require reading glasses to correct this issue.Learn more about Technology
A parfocal lens is a zoom lens that holds its focus throughout its entire zoom range. A varifocal lens, on the other hand, is a zoom lens that requires the lens to be refocused if the focal length is changed.Full Answer >
A lens used in both contacts and eyeglasses works by changing the direction of light and bending it so that it focuses on the retina of the eye. For nearsighted people, a lens "diverges the light rays, which reduces the eye's focusing power," according to Gary Heiting, OD of AllAboutVision.com. This causes the divergent light rays to focus on the retina, instead of before it.Full Answer >
According to Healthline, the retina's function is to receive and convert light from the lens into neural signals that are interpreted by the brain. A thin layer of photoreceptor cells in the retina determines color and light intensity. The optic nerve serves as the conduit between the retina and brain.Full Answer >
Glasses work by adjusting the focal point of light so that the image reaching the retina of the eye is in focus. Opticians cut the lenses to bring the image closer, further away or correct other vision problems, such as double vision.Full Answer >