Pinhole glasses

The effect of pinhole glasses approximated by a camera

An eye chart in sharp focus, as would be seen under normal vision.

A blurred eye chart, as would be seen by an individual with a refractive error.

Pinhole glasses, when placed over the out of focus camera, make the chart somewhat readable once more. However, they darken the image and the grid blocks some of the finer details, requiring slight movements of the camera for the whole chart to be somewhat comfortably read.

Pinhole glasses, also known as stenopeic glasses, are

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 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.^{[citation needed]}

Pinhole glasses have been marketed by various companies on the claim that—combined with certain

The pinhole occluder, 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.

See also

• Snow goggles

References