Presbyopia is a condition of called longsightedness which happens around 40's.
The lens looses it's elasticity and therefore occures this condition, often called short arms.

What is the cause?

Right after our birth our lens became to loose it's elasticity, of course when we are kids/young, the lens has ability to stretch, and we call that accomodation.
However, when we enter 40's the lens loose it's elasticity and isn't capable to change it's shape any more (loss amount of accomodation).

This condition is different from regular farsightedness, nearsightedness or astigmatism, which are related by genetic or shape of the eyeball.

Treatment

Presbyopia can be treated with glasses or contact lenses.

GLASSES

There are of course reading glasses which you put when you have to read some text on a paper, computer, laptop, mobile phone. This solution is good for the people who don't need glasses for everyday life (walking, watching tv, driving).
But if a person needs to wear glasses all time then the best option are bifocals or progressive addition lenses.

Bifocal

Old school lens with far and near dioptry in one lens. It is helpful for those who need to wear glasses through the whole day.
Also a person don't have to have 2 pairs of glasses because can do everything with just one.
The disadvantage is that they have a visible "window" for near vision.

Progressive addition lenses

New and better version of bifocals.
Have attractive design where, unlike bifocals, don't have small "window" on bottom of the lenses. Actually you can't even say on first that those lenses are progressive what gives them an extra aesthetic appeal.
Also they are much better option as they contain bunch of small dioptries inside one lens what gives a coustomer the ability to work at different distances, which is of special importance at today's multitasking era.

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CONTACT LENSES

There are multifocal contact lenses which have multiple dioptries.
Great choice for the ones who don't like wearing glasses but are presbyopes.
Depent on the manufacturer multifocal lenses often comes in low, med or hi available additions.