My unsolicited advice: turn on a lamp in your workspace, and turn down your monitor brightness. An app like twinkle tray makes adjusting screen brightness as easy as adjusting speaker volume. Your eyes really don't care about emissive or reflected light.
I do anecdotally find that the better ambient light causes less eye strain.
Sharper images lead to less eyestrain because you don't need to keep your eye still for as long.
I use light color themes for this reason. Although I always add the caveat to "do what works for you", because everyone's body is different.