Squint

Squinting is the activity of staring at something with half closed eyelids.

Squinting is most commonly used by those who have refractive defects of the eye and either do not have or do not wear glasses.

Squinting temporarily improves their eyesight by gently modifying the shape of the eye to make it rounder, allowing light to properly reach the fovea. Squinting also reduces the quantity of light entering the eye, making it simpler to concentrate on what the observer is looking at by reducing rays of light that enter the eye at an angle and would otherwise need to be focused by the observer’s defective lens and cornea.

Squinting is often thought to impair vision. According to Robert MacLaren, a professor of ophthalmology at the University of Oxford, this is only an old wives’ tale: the only harm caused by prolonged squinting is a brief headache induced by continuous contraction of the facial muscles.