In the United States, approximately 75% of the adult population uses vision correction, inclusive of both eyeglasses and contact lenses (National Eye Institute). The importance of vision, and in turn corrective lenses for the majority of the population, is indispensable. These lenses allow people to read their favorite books, see the faces of loved ones, look at great works of art—they allow people to see the world.
The Human Eye
To understand how corrective lenses work, there must first be a foundational understanding of how the human eye works. The retina, a layer of cells found on the back of your eye, reacts to incoming light and relays the information to your brain. As scattered light enters your eye, three things must happen to the light for visual clarity:
The size of the image must be reduced to fit onto the retina
The light must focus at the surface of the retina
The curve of the image must be matched to the curvature of the retina.