Although my Th times are after work, in the evenings, I have days when I'm on the edge (or over) of tears all day and spend some time letting them flow a bit in the restroom. On days that start out that way from the get-go, I just curl my eyelashes and skip the mascara.

You could also make a little kit to carry with you on therapy days, with mascara remover wipes, mascara to reapply, Visine or something similar to soothe your eyes. And add something special, like your favorite "flavor" (scent) of hand lotion.