Some ancient people thought that our eyes emitted beams of light that allowed us to see whatever we looked at. Today, we know the physics of seeing is exactly the opposite.

Light waves enter our eyes through the cornea, then pass through a lens, which focuses the light on the rear of the eyeball. There, the light excites special nerve endings, called rods and cones, which carry a signal to the brain.

Depending on the shape of the eyeball, the cornea, lens, and retina may not work perfectly together, causing fuzzy vision. That’s why many people wear eyeglasses or contact lenses. They help the light focus images correctly on the retina and allow people to see clearly.