Pinhole glasses are also known as Stenopeic glasses. The term was derived from the Greek words meaning “little opening”. They are eyeglasses with a series of pinhole size perforations. Pinhole eyeglasses are not made up of glass at all but of an opaque substance such as metal or plastic. They are modern and affordable alternative to conventional glasses and provide clear vision, as well as they are effective system for exercising the eyes which is an additional advantage of pinholes over conventional glasses as later makes eyes lazy and weaker with time. In the refractive errors such as myopia, hypermetropia (farsightedness), presbiopia (diminished focusing range with age) and astigmatism they can bring about clear vision. They are ideal for elderly people and computer users.
The working of pinhole glasses is similar to a pinhole camera. In a weak eye, the light rays which are entering into eyes do not focus on to same place on the retina and hence blur image is formed. When the pinhole glasses are used then the rays which have same focus on retina enters the eye and hence a clear and natural image is seen. The additional benefit of these glasses includes relaxing effect on eye muscles as the rays entering into eyes are already in the focus and no any effort is required from the eye muscle for the accommodation.
Pinholes are considered as 100% safe and useful for everyone either young or old. Their obvious advantages over the conventional glasses make them more acceptable. They improve vision clarity and resolution, increase object brightness and provide good vision at all distances. Also they are lightweight, durable, attractive and affordable. That is why they got popularity in recent years.
There are two major limitations of the pinhole glasses. One is that blocking of some light diminishes the intensity of light and second is that peripheral vision is diminished. Hence they should not be used while operating machines, driving and other similar activities involving motion. Pinhole glasses have greatly replaced prescription glasses but they can not replace prescription glasses in every situation.
Traditionally, pinhole glasses had flat or slightly curved lenses of plastic with actual holes punched through them. While, modern pinholes have solid, curved lenses of the same clear plastic used for prescription glasses. These lenses provide full ultraviolet protection. Now-a-days many stylish and well-designed pinhole glasses are available in the market to meet the consumers need.