The eye doctor tests different lenses in front of the patient's eyes to determine what correction is needed. Presbyopia may not need correction for a year or two after symptoms begin. Some people can simply change their reading distance, increase illumination, take frequent breaks from close work or, if nearsighted, remove their glasses to read. Correction of presbyopia involves making up for the lost accommodative power of the lens of the eye. Because the lens of the eye continues to change with age, a stronger reading glass prescription is needed about every two years until the mid-50s or 60s.
Little change is needed after that unless some other visual problem develops.
This provides good vision for close objects but makes distant objects look blurred. Therefore, reading glasses must be removed to see in the distance. These glasses are best for people who do not mind switching between distance and reading glasses, who do not need distance correction or who wear contact lenses for distance. They are also appropriate for people who can not wear bifocals for some reason. Half-glasses leave the top of the glasses open to facilitate distance vision without the need to remove the glasses.