How do Contact Lenses Work?
A contact lens is nothing more than a tool crafted to adjust the optics of your existing biological lens, the human eye. When you suffer from blurred or impaired vision, it is simply due to the fact that your eyes aren’t able to focus the light coming in directly onto your retinas.
Your retina is the layer of membrane at the back of the eyeball; its center dimple, called the fovea centralis, is the sharpest point of vision, as well as where the majority of color is perceived.
Contact lenses are applied to the cornea of the eye, where they operate in largely the same capacity as eyeglasses do – by helping your eye focus the light coming in directly through to the focal part of your retina.
For those with myopia, or nearsightedness, the inability to see farther away is the result of an elongated eyeball, wherein the light that is focused in the eye lands in front of the retina, rather than on it. This is corrected by minus lenses, whose concave shape is thinner at the edges than at the center so to spread the light away from the eye’s lens, adjusting the focal point of the light forward.
Conversely, an eye that is too short is cause for hyperopia, or farsightedness. This contact lens will bend the light toward the center and move the focal point back through its convex design, which is thicker at the center. In this way, the light is focused on the retina, rather than behind it.
Depending on how much the light bends, your vision will require contacts or bifocals of different strengths, which are expressed in diopters: The higher the diopter, the stronger the lens. As for the choice between hard and soft contacts and glasses, that is a matter of personal preference.
Contacts are a universally popular alternative to frames for a few reasons. Most importantly, contact lenses bring the wearer as close as possible to corrected natural sight, since they move with your eyeball, allowing for a more natural field of vision. Contacts do not get in the way of your line of sight, and brands like Biofinity and Acuvue can be worn daily for weeks or even a month before they need replacing.
Applied to the cornea of the eye, contact lenses are able to stay in place by a combination of pressure from the eyelid and adhesion to the layer of tear fluid which floats on the eye’s surface. Each time you blink, your eye will secrete lubrication to the cornea which flushes out bacteria and impurities that may get stuck to the lens. These days, soft contact lenses are more popular as they can be worn longer without causing the same rough irritation as hard lenses. Made of soft, gel-like plastic, the material is designed to absorb water and allow oxygen flow for the sake of both comfort and hygiene.
Other irregularities that can be improved with the use of contact lenses include astigmatism (the curvature of the eye’s lens or an oddly shaped cornea), and presbyopia (the natural aging of the lens). Talk to your eye doctor about what steps you can take to improve your sight today.