Today I went to the eye center and ordered new glasses.  Here is what my prescription was in September 2007:

OD: -4.50 x -1.00 x 174
OS: -3.50 x -1.00 x 178

Now it is somewhat worse:

OD: -5.50 x -0.75 x 176
OS: -4.25 x -1.00 x 166

I was worried that I would need bifocals, since I am over 40.  This turned out to not be the case.  There is a slight degradation in my near vision, but not bad enough to need correction yet.  I might need bifocals in the next few years, though.