The app from Viso Systems is great. I was able to measure my stairway's lighting, which gives me some weird strained feeling around the eyes within seconds.
The PWM rate is the same as my bathroom incandescent bulb. I have no trouble with the latter. I compared both, and these are the results:
The lamp looks a little blue, so one may argue wether it's blue light that's troubling me, but I don't think so. The feeling I get is the same I have when I used my OnePlus 3 in the 240 Hz PWM mode.
But why is the indescandent bulb OK? Same frequency as the staircase lamp. I believe the real enemy is the flicker percentage.
What they calculate as "Percent Flicker" is (MaxValue-MinValue)/(MaxValue+MinValue). Not sure why one would include MinValue in the divisor, too.
Anyway, I urge everyone to get that app and measure any lamps you have trouble with.
We might finally be able to collect some facts which we can compare.
It works on iPad and iPods, too. Select "iPhone only" in the App Store app so you can see it.
And use some kind of diffusor as described on their home page. I used toilet paper :p