Pinhole Glasses have a series of pinhole-sized perforations filling an opaque sheet of plastic in place of each lens. They harness the power of natural light to improve your vision. Each perforation allows 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, reducing blur and enhancing clarity. Eyes with refractive error may help create a clearer image. Pinhole Glasses produce an image without the pincushion effect around the edges (which makes straight lines appear curved). Pinhole glasses are also called stenopeic glasses. Pinhole glasses reduce brightness and peripheral vision, and thus should not be used for driving or when operating machinery. Pinhole glasses exercise the focusing muscles of your eyes and can correct vision permanently when worn for only 15 minutes a day.