How do the eyes focus?
The lens bends light to make an image on the retina. The lens can change its shape to make this image sharp. The lens is flexible, and tiny muscles pull on it to alter its shape and focus the image. Your lens is almost round when you are looking at something close up, but it becomes flatter when you look at a distant object.
How do contact lenses work?
Contact lenses are thin plastic discs that rest on the surface of the cornea. They act like the lenses of ordinary glasses. Most modern contact lenses are made from very soft material that does not cause discomfort to the eye. Some lenses are worn for just one day and then thrown away. It can be difficult to get used to wearing contact lenses and to put them in the eye without scratching the delicate cornea. However, many people prefer them to wearing glasses.
Why do some older people need reading glasses?
As people get older, the lenses of their eyes grow harder and cannot change their shape to focus close up. Reading glasses provide sharp vision close up. Some people wear bifocal glasses, where a small area of the lens is shaped for close-up vision, while the rest of the lens is suitable for distant vision.
Pictures Credit: Google
