Ask this question to any scientist and they will tell you it is all about light refraction, and we have to go back to that legendary Italian inventor, Leonardo Da Vinci, who, in the 17th century pioneered the idea that water directly in contact with the cornea could alter a person’s vision. Of course, the idea never amounted to anything, as they did not have the glass cutting technology, nor the plastics that we do today, and over the next 300 years, ideas were proposed and when we finally had the technology to produce thin and very accurate lenses, contacts were born. Here’s a brief explanation of how contact lenses work.
Errors in light refraction cause short or long sightedness; if a person is short sighted, this means the rays of light meet in front of the retina, and the extra lenses bend the light to make the focal point inside the retina, where it should be for perfect vision. The same principle works with eyeglasses; the shape of the lens bends the light as it approaches the eye, changing its direction slightly, allowing the person to focus clearly. The opposite works for long-sighted people, where the eye cannot focus properly on the light rays that have not yet converged, and the lens will bend the rays of light to make them converge at the surface of the retina.
Plus and Minus
Lens correction has become very precise and complex, with a system of positive (+) and negative (-) numbers to measure the light refraction. The measurements of lens powers are expressed in Diopters, with lens powers that correct near-sightedness using the minus sign (-), while those that correct far-sightedness start with a plus (+).
Since the 1960s, contact lenses have been developed in an ongoing way, and as technology empowered us with fine cutting and shaping of special soft materials, we created contact lenses that are very effective and comfortable to wear. Indeed, if you want to view the very latest in coloured contact lenses, check out the stunning collection at Lulu Lenses, who are approved retailers for Anesthesia, an Australian company that makes the best contacts in the world.
Distance to the Eye
When wearing eyeglasses, the lens is approximately 12mm from the eye, and because of this, the refraction correction would need to be large, yet the contact lens is worn on top of the cornea, and due to close proximity, the refractive correction is much smaller, allowing for very thin lenses. As an analogy, imagine you are in a house and are looking out of the window; if you are standing back from the window, then your field of vision would be limited by the window frame, yet if you stand right at the window and look out, you have a much wider scope of vision. The contact lens sits right on the cornea, which is the most effective placement for the corrective lens, and with innovative technology, we now have contact lenses that, when attached, feel no different than not wearing them.
If you know your lens number (the plus or minus number), any optician can create the right lenses for you, which means you can purchase contact lenses online, where all the best deals are to be had.