Poor contrast is what kills your eyes. You should adapt your screen to your environment.

Problem is, not many screens can compete with the of light of a sunlit room for daytime viewing. That makes dark (text) on dim (background) on light (environment) very rough. Even for daytime viewing light (text) on dark (background) on light (environment) can feel better.

But dark (text) on (light) background on light (environment) is excellent if you can accomplish it, since it’s only single step of high contrast because your monitor blends into the environment.