The word ‘presbyopia’ means ‘old eye’ in Greek. It is a normal part of aging where your eyes gradually lose their ability to see things clearly up close. From around 40 you may find that you hold reading materials farther away to see it clearly. In young people the lens is soft and flexible and easily changes shape. After 40 the lens becomes more rigid and cannot change shape as easily. This causes the difficulty in reading and other close up tasks
A laser is used to reshape the cornea to adjust each eye in different way. The two eyes are corrected for opposite results: One eye is adjusted to see mostly at distance, and a little close up. The other eye sees mostly up close, and a little at distance. The brain combines the two images for enhanced depth of field and improved visual acuity.
This is when someone with presbyopia chooses to replace his or her natural lens with an intra-ocular lens (IOL), usually a multifocal lens. This allows them to have an IOL that corrects a refractive error (nearsighted, farsighted, or astigmatism). The surgery is similar to cataract surgery. Implantable multifocal lenses have several rings or zones set at different powers. With this design, you are actually using both near and far vision Iat the same time. Your brain learns to automatically select the correct focus for what you want to see.