Presbyopia is the inability to focus on objects up close.
During normal vision, light passes through the cornea, and then through the pupil, which is actually a hole in the colored part of the eye. Light then passes through the lens where it is focused at a point on the retina at the back of the eye. At this point, the image is converted into electrical signals that are sent to the brain.
The lens is flexible and can change its shape to focus light onto the retina. The focusing power of the eye depends on the elasticity of the lens. As a person ages, the elasticity in the lenses decrease, causing presbyopia.
A presbyopic person sees faraway objects clearly. However, the images of nearby objects focus behind the retina, causing these objects to look blurred.
Symptoms of presbyopia may include tired eyes, headaches, and blurred near-vision. People often notice the first symptom of presbyopia when they need to hold reading material farther away from themselves in order to focus more clearly.
Presbyopia normally occurs in people over the age of 40. A doctor may prescribe reading glasses to correct this vision deficiency.