Pinhole eyeglasses are an interesting invention in the world of optometry. Otherwise called stenopeic glasses (or “little opening” in Greek), each metal or plastic “lens” has a series of tiny perforations, usually no larger than a pin’s head. Light enters through each perforation, increasing the depth of field and giving the retina no “blind spots”. Only what is directly in front of the retina is taken into vision. The Chinese discovered pinhole technology in the 5th century, and these glasses were used by the public beginning in the middle of the 20th century. A pinhole camera follows the same technology.
Typical prescription glasses produce a pincushion effect near the edges of the line of vision, in that straight lines seem distorted and curvy. Pinhole glasses block these outer lines and only allow vision by the middle of the pupil. Additionally, the further an object is from the wearer, the better it can be seen.
Compared with prescription eyeglasses, pinhole glasses differ in several different ways. Whereas a user may have to continually upgrade their traditional eyeglasses as their vision changes, this is not the case with pinhole eyeglasses. They can, technically, last a lifetime. They also do not need to be cleaned of smudges and are nowhere near as fragile. However, they should not be worn while driving or performing other rapid activities as they limit periphery vision. They are best used during activities in which you are stationary, such as watching television or reading a book.
While older models of pinhole glasses have obvious perforations, newer models are more attractive. Modern pinhole glasses are more curved near the edges, and some can even pass as traditional sunglasses. Some even provide full protection from ultraviolet rays and include a minor mirror coating to be more reflective and better disguise the perforations from others.