Why Squinting Helps Us See Better

The eyeball is an amazing piece of human architecture. But because of its complexity, it can easily fail. The most common way for the eyeball to fail is for it to lose its elasticity. When that happens, light entering the eyeball is minutely diffracted (spread) throwing off the focus, resulting in near- or farsightedness. The result is a need for glasses to compensate and refocus the light before it hits our eyes.

Another way to focus incoming light is to squint, which both reshapes the eyeball and limits incoming light. We can also look through a tiny hole, like a pinhole in a piece of cardboard or our curled finger. These things limit diffraction, allowing our eye to “make sense” of a more limited set of incoming signals.