From a recent study published in the journal Cephalgia 

Proper migraines* increase with time spent on computers, smart phones and TV combined. (*typically one-sided headache with photophobia +/- nausea +/- visual distortion)

There was no relationship between use of these devices and common headache.

Work implications:

Of course explore the usual workstation basics but perhaps suggest less recreational computer and smartphone time for those with migraines.

Reassure those with headaches that (if vision for screen distance is OK and workstation basics in place) computer use at work is unlikely to be a significant contributor.

*From a recent study published in the journal Cephalgia