Given that I have a similar problems I know what you're experiencing. It's unlikely that the refresh rate will make a significant difference above 60Hz on a decent monitor. First ensure that you're using a digital connection, either DVI or HDMI, analog connections make the problem worse. Make sure you're running at native resolution if possible, scaling may introduce artifacts. You're also going to have to tweak the fonts to make sure they look sharp and consistent. Depending on the version of Windows you're using there's an option for improving fonts on an LCD, you're going to have to look closely at the fonts to make sure that the letters on one part of the screen look the same as letters on another part, LCD smoothing tends to give funky effects and you'll have to see what works best. Finally make sure that if your monitor is running 60/75Hz your graphics settings are set the same. You'll still get an image if it's running at 59Hz but there are artifacts that may cause you issues.
Finally you're eyedoctor should have given you advice for when you're staring at a screen for hours on end, make sure you follow it.