I've been short-sighted with an astigmatism since I was about 8. About age 45 my eyes started changing rapidly. I have to have my sign tested every year as my prescription changes so much sometimes getting better, sometimes getting worse. I've been presribed varifocals but, working with a PC all day, I find they give me a crick in my neck as I have to hold my head back to bring the screen into sharp focus.
I find I get better results from contact lenses to give me good distance vision and add +1.25 diopter reading glasses when I need to read small or close up text.
Go visit a reputable optician, have a full sight test and tell them what you do for a living and how much of your life is in front of a computer screen.
Don't be shy about rearranging your desk & monitors, pull the monitor closer or push it away, to make life easier and zoom the display in IE, Outlook or Word if you need to. Ctrl+ScrollWheel is your friend. Ctrl+0 to go back to 100% zoom.