Presbyopia is age related farsightedness. The crystalline lens inside the eye losses flexibility over the years. At an age around 40 years the eye is not able any more to focus on objects in front of the eye in "normal" reading distance.
Presbyopia is corrected with reading glasses with a positive optical power. These glasses only help when reading, in the distance they cause a blurred vision.
Presbyopia in combination with myopia or hyperopia is corrected with bifocal or multifocal lenses.
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