Pinhole glasses consists of opaque lenses packed with a grid formation of pinhole-sized perforations. Like the mechanics of a pinhole camera, the pinholes permit a highly narrow beam of light to penetrate the eye thereby minimizing the circle of confusion surrounding the retina and thereby heightening the depth of field. This results to sharper images from eyes with refractive errors.
Light rays are focused and converge into a singular point on the retina. Eyes with refractive errors diverge light rays on various mislocations thereby casting blurry images. Viewing through pinholes correct these issues, allowing a narrower light beam and improving the depth of field. The result is less blurring and clearer images.
In addition, pinhole glasses diminishes brightness and peripheral vision, which can be adverse for alert activities such as machine operation and driving. Prescription glasses, on the other hand does not have this deficiency. It also helps myopia by producing clear images without the pincushion effect of pinhole glasses, where straight lines appear curved.
The claim is that pinhole glasses, along with eye chart exercises can reverse the refractive errors of the eyes. Scientific evidence has not been established to support this benefit, in so far as the United States Federal Trade Commission have outlawed these claims.