Anyone who is nearsighted knows how inconvenient it is to forget or break their prescription glasses at home. However, if you find yourself in this situation, don’t worry too much because a temporary solution lies in your own hands.
As explained in detail and convincingly by MinutePhysics, blurry images are formed when light enters your eye and spreads too widely on the retina. If you use your fingers to create a tiny circle and hold it right in front of your eyes, it will only allow certain beams of light to cover your retina, mimicking the effect of a pinhole camera. At this moment, you’ll see everything more clearly than before.
To understand why this tip works, we need to return to the mechanism of human vision. For you to see something, light needs to travel from a light source, shine onto an object, and then reflect into your eyes, onto the retina, to form an image of that object.
If there were no lenses in your eyes, light reflected from the object would scatter and reach the retina from all different directions, leading to a chaotic, blurry mess.
This is a viable temporary solution for nearsighted individuals in unavoidable situations.
That is why when you look at something in front of you, everything in the background and foreground will appear somewhat blurred and unclear. At that point, the lenses in your eyes can only focus on light coming from a distance. If the object is too close or too far from your lenses, the light reflecting from it will naturally spread across the retina, causing the image you perceive to be blurry.
This is when the muscles in your eyes can contract the lenses to adjust your vision. If this mechanism doesn’t work well, prescription glasses (for nearsightedness or farsightedness), contact lenses, and surgery can help you focus on objects near or far.
The pinhole tip from MinutePhysics is effective because when light travels through a small space, it can converge from any distance. And because the entrance is very small at this point, light can only travel through one position, meaning we no longer face the issue of light hitting the retina at multiple points, which causes blurriness.
You may look a bit odd performing this tip in front of a crowd, but it is a viable temporary solution for nearsighted individuals in unavoidable situations.
