There are plenty of different options for a person to correct their less-than-perfect vision these days. From glasses and contacts to corrective laser surgery, we've pretty much thought of everything. But if you're in a pinch, say, your contact lenses fell off the counter and disappeared, or your glasses have been smashed by a bloodthirsty gang of shipwrecked schoolboys, MinutePhysics has got you covered.
In the episode above, Henry Reich runs us through a quick and easy trick to correct your own vision, no lenses or surgery required. "Make a tiny, tiny hole using your fingers, look through it, and the world will be come clear again," he says. "This works, no matter how blurry your vision is. Take off your glasses and give it a try."
The video even has an reading test so you can see how the trick works.
But how is such a simple fix possible? To understand it, we have to think back to how seeing actually works. Put very simply, for you to perceive something, light needs to travel from a source, bounce off on object, and then travel into your eye to be projected onto your retina, where it will form an image of that object. If it weren't for the lens built into our eyes, light bouncing off an object would split and hit the retina in all different places, resulting in you seeing nothing but a smeared-out mess.
This is why when you see something in front of you, everything in the background and foreground will be slightly blurry - the lens in our eye can only focus light coming from one distance away, says Henry. If an object is too near or far from your lens, its light will be naturally spread across your retina, causing the image you perceive to be blurred. And that's where the muscles in our eyes that can contract the lens come into play, and when those don't work properly, glasses, contacts, and surgery help us to focus on near and far objects.
The reason the MinutePhysics pinhole trick works is because when light travels through a small space, it's able to be focussed from any distance. Because it's such a small opening, light can only travel through in one place, which means we no longer have the problem of light hitting the retina in multiple places. The key is blocking, rather than focussing, light.
Watch the MinutePhysics episode above to find out more, and don't forget to give this trick a try - it works no matter how good or bad your eyes are. You'll thank us when your prescription has been screwed up and you accidentally eat an onion like an apple: