Over on Reddit, one user has an unusual question about their vision: why is it improved by looking through the holes in Country Cheese crackers?

"I was just in bed eating crackers and decided to look at the TV through the holes in the cracker," the Redditor explained in the AskScience subreddit, "low and behold I could see clearly."

Strange as this sounds, it is actually a thing. Of course the effect is not limited to Country Cheese crackers, nor crackers in general.

Known as the pinhole effect, all you need to do is to create a small hole in a piece of paper, or a small hole between your fingers, in order to improve your vision.

"When light passes through a small pinhole or pupil, all unfocused rays are blocked, leaving only focused light to land on the retina to form a clear image," Associate Professor at Pennsylvania College of Optometry Bisant A. Labib explained in Review of Optometry. "The size of the pinhole aperture or pupil size is an important consideration. While there is great benefit [...] to limiting marginal and unfocused rays from reaching the retina using a small aperture, a pinhole or pupil that is too small may cause diffraction and loss of resolution."

This doesn't work for all vision defects, only refractive errors that can be corrected using lenses or contacts.

"This is actually a technique we use in the clinic when a patient comes in having blurry vision and we want to know really fast if the blurry vision is a refractive condition, meaning they need glasses or contacts," optometrist Dr Neal Guymon explained for his YouTube channel Dr EyeGuy.

"We'll put pinhole glasses right over that eye, and if their vision improves then likely glasses or contacts will improve their vision. If we do it and their vision does not improve then likely something else is going on, a medical condition [or] something going on [in] the back of the eye that's causing the blurry vision."

Vision problems are, of course, best dealt with by visiting a health professional. But in a pinch, a cracker with a small hole in it may help you focus a little better.

The content of this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of qualified health providers with questions you may have regarding medical conditions.

All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current.