Apologies if this has already been suggested (I haven't read all the answers).

You can turn your screen black to white, i.e. inverting everything, so you're reading white type on a black background.

At times with my eye troubles, I've done this, and it really helps.

Route: System Preferences / Accessibility (down the bottom) / choose Display / click box marked 'Invert Colours'.

While you're there you can also get rid of colours if you click 'Use greyscale'.

Quite a few things there are helpful, like GIANT cursor.

Good luck.

Allen.