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Presbyopia is caused when the centre of the eye lens hardens making it unable to
accommodate near vision.
This condition generally affects almost everyone over the age of 50 - even those
with myopia.
Eyeglasses with bifocal or progressive lenses are prescribed to correct or
improve the condition.
The contact lenses used by presbyopes are multifocal lenses.
| Progressive lenses -- Also called
progressive addition lenses or PALs are multifocal lenses whose corrective
powers change progressively throughout the lens. A wearer looks through one
portion of the lens for distance vision, another for intermediate vision, and a
third portion for reading or close work. Each area is blended invisibly into the
next, without the lines that traditional bifocals or trifocals have.
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