Dimming the screen won't help, since the contrast is probably the problem. I am guessing that, since you have the same problem on two different monitors, the problem can most easily be resolved within Windows.
I'm not really sure which version of Windows you're on. One way to deal with this might be available on the function keys at the top of your keypad. Look for a pair of function keys with symbols that look like a starburst of light, with the one on the right being larger than the one on the left. You will probably need to hold down the "fn" (function) key when you use them.
If that doesn't work, see below.
If you're on Windows 7:
Choose Start, Control Panel.
In the Control Panel, choose Appearance and Personalization.
On the next screen, click on the link that says “Change the theme” (under Personalization).
Scroll down and select a theme in the Basic and High Contrast category.
If you're on Windows 8:
Press the Windows ( ) key + C, or swipe in from the right edge of the screen to open your Charms.
Click or tap Brightness, then slide the bar up or down to adjust your brightness.
If you're on Windows 10, go to Settings > Display.
If none of this helps, search for adjusting contrast/brightness in your version of Windows and/or for your laptop.