Squinting is the action of looking at something with partially closed eyes. Squinting is most often practiced by people who suffer from refractive errors of the eye who either do not have or are not using their glasses. Squinting helps momentarily improve their eyesight by slightly changing the shape of the

eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

to make it rounder, which helps light properly reach the

fovea Fovea () (Latin for "pit"; plural foveae ) is a term in anatomy. It refers to a pit or depression in a structure. Human anatomy * Fovea centralis of the retina * Fovea buccalis or Dimple * Fovea of the femoral head *Trochlear fovea of the f ...

. Squinting also decreases the amount of light entering the eye, making it easier to focus on what the observer is looking at by removing rays of light which enter the eye at an angle and would need to otherwise be focused by the observer's faulty lens and cornea. Pinhole glasses, which severely restrict the amount of light entering the cornea, have the same effect as squinting. It is a common belief that squinting worsens eyesight. However, according to

Robert MacLaren Robert E. MacLaren FMedSci FRCOphth FRCS FACS VR (born 14 November 1966) is a British ophthalmologist who has led pioneering work in the treatment of blindness caused by diseases of the retina. He is Professor of Ophthalmology at the Un ...

, a professor of ophthalmology at the University of Oxford, this is nothing more than an old wives' tale: the only damage that can be caused by squinting for long periods is a temporary

headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...

due to prolonged contraction of the facial muscles. Squinting is also a common involuntary reflex, especially among people with light colored eyes, during

adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...

to a sudden change in lighting such as when one goes from a dark room to outdoors on a sunny day to avoid

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

or discomfort of the eyes. The pupillary light reflex caused by adjustment to light takes around five minutes in people with healthy eyes, so squinting and pain after that could be a sign of photophobia.

References

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