Why do some people need glasses?

Different eye problems cause trouble with a person's vision. Some of the most common ones have to do with the way the eye bends light. Your eyes need to bend light rays so the image can be focused sharply on your retina. The better your retina records the image, the more likely that your brain will interpret the image, and the more likely you will see the image clearly. Glasses and contacts can help a person's eyes bend the rays of light better, which sharpens the image on the retina.