Apparently they can cause some trouble:
Bifocals can cause headaches and even dizziness in some users. Acclimation to the small field of view offered by the reading segment of bifocals can take some time, as the user learns to move either the head or the reading material rather than the eyes. Computer monitors are generally placed directly in front of users and can lead to muscle fatigue due to the unusual straight and constant movement of the head. This trouble is mitigated by the use of trifocal lenses or by the use of monofocal lenses for computer use.
So I´d suggest checking out that before buying a pair.
Going to an optician to get a proper pair should reduce the fatigue... but its always best to have a look at it before buying them
I appreciate the details, V! Currently I just take off my glasses (which I very much need
for distance vision) when I want to read or do anything else up close. Maybe I should just
keep doing that, and keep my glasses on a chain so I don't lose them, as I tend to do
when I put them down absent-mindedly. I am
very near-sighted!