Eyeglasses causing eye strain and pressure

I normally wear contact lenses with no problems, but when I put on my
eyeglasses, my eyes feel like they're straining, and there is a
feeling of high pressure all around my eyes. I can see just fine with
these glasses, but the pressure disallows me from wearing it for more
than an hour at a time. I never had this problem with glasses before,
but when I asked my optometrist last year, she said it was just an
adjustment to new glasses. I'm not so sure i buy that, because i had
been wearing them for a year up to that point. Well, now it's been
over 2 years since I got the glasses, and the pressure hasn't
subsided. Any suggestions as to what this can be?

I also tried wearing one of my old glasses to see if they would cause
pressure, and unfortunately they did. However, these old glasses were
a much lower prescription so I'm not sure if that had anything to do
with it.

Thanks in advance,

Jason