Pinhole glasses, also known as stenopeic glasses, are

eyeglasses Glasses, also known as eyeglasses or spectacles, are vision eyewear, with lenses (clear or tinted) mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms (known as temples or ...

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 A pinhole camera is a simple camera without a lens but with a tiny aperture (the so-called ''pinhole'')—effectively a light-proof box with a small hole in one side. Light from a scene passes through the aperture and projects an inverted image o ...

, each perforation allows only a very narrow beam of light to enter the eye which reduces the size of the

circle of confusion In optics, a circle of confusion (CoC) is an optical spot caused by a cone of light rays from a lens not coming to a perfect focus when imaging a point source. It is also known as disk of confusion, circle of indistinctness, blur circle, or bl ...

on the retina and increases

depth of field The depth of field (DOF) is the distance between the nearest and the furthest objects that are in acceptably sharp focus in an image captured with a camera. Factors affecting depth of field For cameras that can only focus on one object dist ...

. In eyes with

refractive error Refractive error, also known as refraction error, is a problem with focus (optics), focusing light accurately on the retina due to the shape of the human eye, eye and or cornea. The most common types of refractive error are myopia, near-sightedne ...

, the result is often a sharper image. However, a second effect may appear at the common bridge between each two adjacent holes, whereby two different rays of light coming from the same object (but each passing through a different hole) are

diffracted Diffraction is defined as the interference or bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture. The diffracting object or aperture effectively becomes a s ...

back toward the eye and onto different places on the retina. Unlike conventional prescription glasses, pinhole glasses produce an image without the pincushion effect around the edges (which makes straight lines appear curved). While pinhole glasses are claimed to be useful for people who are both near- and far-sighted, they are not recommended for people with over 6

diopters A dioptre (British spelling) or diopter (American spelling) is a unit of measurement with dimension of reciprocal length, equivalent to one reciprocal metre, 1 dioptre = 1 m−1. It is normally used to express the optical power of a lens or cu ...

myopia Near-sightedness, also known as myopia and short-sightedness, is an eye disease where light focuses in front of, instead of on, the retina. As a result, distant objects appear blurry while close objects appear normal. Other symptoms may include ...

. Additionally, pinhole glasses reduce brightness and

peripheral vision Peripheral vision, or ''indirect vision'', is vision as it occurs outside the point of fixation, i.e. away from the center of gaze or, when viewed at large angles, in (or out of) the "corner of one's eye". The vast majority of the area in the ...

, and thus should not be used for driving or when operating machinery. Merchants state that after prolonged use, the plastic grating should become easy to ignore. However, each time the user blinks, the horizontal lines of the grating will briefly appear to be thicker. This is because the eyelid moving over the pupil will reduce the amount of light falling onto the retina and thus will briefly remove the

lateral inhibition In neurobiology, lateral inhibition is the capacity of an excited neuron to reduce the activity of its neighbors. Lateral inhibition disables the spreading of action potentials from excited neurons to neighboring neurons in the lateral direction ...

effect which normally makes all the holes appear bigger (and the grating appear thinner). So, as long as the user keeps blinking, they will be constantly reminded of the dark grating covering their eyes. Pinhole glasses have been marketed by various companies on the claim that—combined with certain

eye exercises Vision therapy (VT), or behavioral optometry, is an umbrella term for alternative medicine treatments using eye exercises, based around the pseudoscientific claim that vision problems are the true underlying cause of learning disabilities, parti ...

—they could permanently improve eyesight. However, no scientific evidence has been found to support these claims. Due to a lack of formal clinical studies to substantiate this type of claim by companies selling pinhole glasses, this type of claim is no longer allowed to be made in the United States under the terms of a legal settlement with the

Federal Trade Commission The Federal Trade Commission (FTC) is an independent agency of the United States government whose principal mission is the enforcement of civil (non-criminal) antitrust law and the promotion of consumer protection. The FTC shares jurisdiction ov ...

. The

pinhole occluder A pinhole occluder is an opaque disk with one or more small holes through it, used by ophthalmologists, orthoptists and optometrists to test visual acuity. The occluder is a simple way to focus light, as in a pinhole camera, temporarily removing ...

, a device used by ophthalmologists and optometrists for diagnosis of refractive errors, works on the same principles, but is not intended for use outside of diagnosis.

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{{DEFAULTSORT:Pinhole Glasses Corrective lenses

See also

References

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