Presbyopia is a vision condition in which the crystalline lens in the eye loses its flexibility. The lens of the eye focus's the image upon the retina. The image is actually inverted but the brain interprets the image as the right way up. For distant objects, the lens becomes elongated and less refractive. For close objects, the lens becomes rounded and more refractive. If the leans cannot adjust its shape enough, the image will be focused behind the retina and hence will appear out of focus. This makes it difficult for you to focus on close objects. Presbyopia usually becomes noticeable in the early to mid 40s. It is not a disease and it cannot be prevented. Some signs of presbyopia include a tendency to hold reading materials at arms length, blurred vision at normal reading distance and eye fatigue along with headaches when doing close work. A comprehensive eye test will include testing for presbyopia. To help you compensate for presbyopia, your optometrist can prescribe reading glasses, bifocals, trifocals or contact lenses.