I wear trifocals..ugh..hate them. And I think that's why I get such a pain in the back of my neck. I find myself cocking my head forward so I can see through the bottom third of my glasses. Every once in a while I half to stop for the pain and do yoga or other twists to relax everything. I start out I think with the correct posture but then next thing you know I'm a chicken neck again. Ouch!