People are shocked after finding out that others can't perform a simple trick with their eyes.
NHS Surgeon Dr Karan Rajan (@drkaranraj) has taken to TikTok to run us through what people are calling a 'superpower' vision hack.
In a recent video, the Sunderland University lecturer commented on a clip of a man boasting about being able to defocus his eyes on command.
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"POV: you are one of those who know how to blur their eyes," they wrote on the text underlay.
However, Dr Karan said: "Congratulations, you've unlocked the world's most useless superpower.
"When you focus on an object, your ciliary muscles contract.
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"This causes the lens in your eye to become fatter and rounder. It increases the refractive or light-bending powers of the lens, helping the light rays to be focused at the retina at the back of the eye so you see things more clearly.
"When you intentionally unfocus your eyes, you're doing a manual system override.
"You are voluntarily relaxing the ciliary muscle. And just like biological play-doh, you turn that lens thinner and flatter.
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"This reduces the refractive power of the lens, leading to a blurred image.
"This cheat code you've activated has a name, 'negative accommodation'.
"Or 'intentional divergent squint', because your eyes slightly drift apart."
Opening up on the possible dangers, Dr Karan added: "This is usually harmless, but since the eye's natural resting state is at a point in the distance, excessive unfocusing can lead to visual strain and fatigue.
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"Constantly shifting between focused and unfocused states might overstimulate the ciliary muscle and the eye's focusing mechanism.
"And repeating this divergent squint too often could disrupt your normal binocular vision, coordination between the eyes, and eye alignment."
If you want to carry on doing it, he advises: "Glitch out, but in moderation."
Commenting on the clip, some viewers 'thought everyone can' do it, as one questioned: "Can't everyone do it? I'm really surprised by it."
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A second also argued: "Most useless superpower? WRONG!! I was always the fastest kid to see all the Magic Eye illusion books in school."
"I used to be able to do it and thought everyone can, but at 54 years old I wear glasses as everything permanently blurred without it, no longer can control it at will," a third wrote.
While a fourth cautioned: "I can do this and shake my eyes lol but I defo don't do it often as I have tripped over or walked into something doing it for fun lol."
Anish Vij