Since getting OLED displays I've started using more all black themes. Especially at night it helps decrease the amount of light my phone emits significantly (or so it seems).
And OLED screens power consumption is proportional to how much color/white is displayed, so black uses less power. Good for your battery, and the environment too.
In a dark room or outside at night, black on an OLED is truly black and everything else floats magically in the void, it's a wonderful effect.
Back when we had CRTs where black also meant no light, you could have real dark in the room if you only had a terminal with green on black or white on black on the screen :)
There is the problem of "OLED smearing"[0] with pure black that makes using it somewhat unviable. It seems that some OLEDs are more susceptible than others, though. Also fairly certain that this only happens with #000.
All LCD technologies have pixel transition times that vary based on the old and new colors and are often larger than the refresh rate, this is nothing new with OLED. Typically these do get improved over time. I've compared the video on my OLED phone and non-OLED monitor and the smearing is not significantly different.
Astigmatism in both eyes and I still use it although my glasses help somewhat. I find that it's usually not all that bad at night when it comes to the halos around text or doesn't really bother me enough vs adding more light by going with a lighter grey theme.
I have pretty bad astigmatism and love white on black in a dark room on an AMOLED screen with the brightness turned way down. It's the only screen I can look at for over 10 hours without getting a head ache.
At night, I can barely see my finger against the empty Feedly screen. Too bad not all applications (looking at you, Strava and MFP) provide an OLED-compatible dark theme and the "Force dark mode" dev setting does not persist after a restart.
I do the same thing. Black background with white text is by far the best contrast setup for reading hands down, it's better than reading paper or e ink. The only thing entering my eyes is the information I want to see, since I started reading this way I cannot purchase a mobile device without OLED.