Presbyopia shows itself when reading and near vision become difficult and close objects need to be held further away. It is not a disease and typically occurs from about 45 years of age when the muscles within the eye are no longer able to change focus to see close up. Rays of light from a near object are focused behind the retina. It happens irrespective of either short or long sight but usually occurs earlier with long sight since the eye may already be focusing to correct distance vision. The remedy is to use reading glasses or bifocal/varifocals.
Contact lenses are now available as either varifocals or single vision and can therefore replace spectacles in most cases.
Illustrations © and reproduction courtesy Simon Levy.