which are also referred to as stenopeic glasses ("little opening" in Greek) are a lot like a pinhole camera. They only allow a small beam of light through, which increases the depth of field. The have small holes on a piece of plastic, where there normally would be a lens. They are normally made fully of plastic or metal. All of this helps give a much more clear picture.
are normally recommended for people that are both near sighted as well as far sighted. They are not recommended for use while driving or using any form of heavy machinery. The companies that provide for sale claim that with the right form of eye exercise and the use of these glasses, your eyes will not only feel a whole lot better, but they might even improve your vision in the long run. There have been studies done on these claims from the providers and there has been no scientific proof to back this up.
A good way to demonstrate the use of is by putting your fist up to one of your eyes and closing the other. You then would open up the eye that is covered just enough so there is a small hole to look through. You should be able to see more clearly this way, if you have a refractive error. The same effect happens if one were to squint slightly. Now if you were looking through it would cut off all peripheral rays from your side vision and you would be able to see a whole lot better. After a good amount of use your brain will start to ignore everything, but what needs to be seen.
are used for people with cataracts as well as for people who enjoy wearing sunglasses. These glasses are not only great for the eyes, but are comfortable and in the long run will save you a lot of money and discomfort.