I've been using pilocarpine for just over a year now.  My doctor prescribed a special formula, it is .1 instead of .25.  The .25 was too strong and had pain quite frequently.  After he prescribed the diluted formula I was able to use it much more often and with much more relief.  I don't use it every day, but when my eyes seem to be under a lot of stress I put them in and it helps greatly.