How do glasses work?
In: Technology
I’ll try my best
At the back of our eyes, there are nerves to receive light (what we see).
That light goes through our eyes where there’s a lens (the centermost circle of our eyes). What these lenses do is they take all the light that would otherwise go in a straight line, and bend them, so that they all focus onto one spot on the nerves.
Normal eyes would have normal, properly working lenses, meaning the image/light going into the eyes would be properly focused. But some of us have abnormal ones (too thin, too thick, or damaged in other ways) and so the focus is off (too far backwards, to far forward from the nerves). When this happens, the nerves dont get focused images, so what we see arent focused.
So eye doctors find out how much thinner or thicker it is compared to normal ones and prescribe you with glasses 😀 which are just bigger versions of the little lenses in our eyes. These bigger lenses are curved in whatever way the doctor sees fit and they pre-bend the light rays that would then pass through the abnormal eye lenses. The point is so that the focus goes back onto the nerves.
Hope this helps, ama!
Depending on your exact issue with vision, you may not be able to see objects close to you or at a distance. This is caused by an issue with the lens of your eye being unable to focus light effectively on your retina. If near-vision is a problem for you, this means your eyes focus light onto a point that is ‘before’ your retina. In this case, concave glasses which cause rays of light to diverge from each other, allows for light to be focused correctly on the retina by the lens of your eye. If far-vision is a problem, the lens focuses light on a point ‘after’ the retina. In this case, the glasses will be convex. The lens of your eye then finishes the job, and focuses light on the retina correctly. Bifocals work by having convex and concave lenses in different parts of the spectacles.
Glasses as in spectacles??
They are usually concave or convex depending on your problem (myopia or hypermetropia).
Myopic people use concave lenses. The problem with myopia is that the light rays converge before reaching the retina. The image is sharp at the focal point and for a normal person the focal point is at the retina but in myopics the focal point is before the retina. So they have a distorted image.
A Concave lens diverges the incoming light rays a bit before it hits the cornea and lens so that it when it converges it does so at the retina
In the same way in hypermetropic people, the light rays converges at a point beyond the retina.
A convex lens is used in this condition and it helps in converging the light rays further so that it properly focuses at the retina.
There are also other conditions such as astigmatism, where the corneal thickness varies and the image is distorted and wavy, in such conditions a cylindrical lens is used to correct
Hope this helps!!
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