Pinhole glasses
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Pinhole glasses, also known as stenopeic glasses, are eyeglasses with a series of pinhole-sized perforations filling an opaque sheet of plastic in place of each lens. Similar to the workings of a pinhole camera, each perforation allows only a very narrow beam of light to enter the eye which reduces the size of the circle of confusion on the retina and increases depth of field. In eyes with refractive error, the result is often a clearer image. Unlike conventional prescription glasses, pinhole glasses produce a clear image without the pincushion effect around the edges (which makes straight lines appear curved). While pinhole glasses are useful for people who are both near- and far-sighted, they are not recommended for people with over 6 diopters of myopia. It should also be noted that pinhole glasses reduce brightness and peripheral vision, and thus should not be used for driving or when operating machinery.
