Its not PWM, all my screens are PWM free confirmed with various tests. Thats why I purchased them I was very sure to get PWM free screens.
Its the same as the OSX issue, looking at a Macbook for a few moments starts a fire inside my head and it hurts for hours / days. Connecting to a GOOD external screen causes it to be BAD. My personal laptop and work t540 are fine on my external screens for hours, the T460 or macbook pro 2013 13' on the same external screens cause the same symptoms - even though the T460 and my personal laptop have the intel HD520.
PWM is a different sensation to me, it hurts my eyes whereas this 'issue' is like a burning pain in the middle of my head that can radiate towards the top, then sometimes it feels like a tight band around my head sort of pressure / crushing pain and I feel sort of sick and diorentated.
Due to the coronavirus my recent doctors appointment was via phone and he was not impressed by everything that I tried to explain, he said its just migraines and that I should stop looking at trigger items. So basically I'm going to work in IT but not be able to use computers. Going to suggest I start on some medication - at this point I'm willing to try anything even though in the past it hasnt helped. Going to ask to see a more qualified eye doctor as well to try and rule out convergence issues etc. - I'm already doing eye 'exercises' but so far no help.
Anyway I rolled the T460 back to 2017 in the BIOS, thats as far back as I can take it. Rolled back Windows drivers as well but also still bad. Might format and re-do windows.
Also same on Ubuntu on the T460 - as is my macbook. Tried that with W10, Ubuntu 19 and elementaryOS. Causes the same issue.
Other than that I am also fully willing to go insane and just buy loads of machines to try and hopefully be able to return them if they're bad....ebay here I come I guess....
The ONE thing thats possibly an issue is the screen on the T460 is damaged already, it has pressure marks where its much brighter so i cover that bit with a small piece of tape....I'm wondering if the damage is partially a problem so looking at a replacement screen.
ALSO, my 2018 iPad is totally fine for me, but If i turn 'reduce white point' OFF it gives me similar symptoms.
I previously had similar but not as pronounced symptoms when using android devices with 'eye care / comfort view' (warming the screen color temp) set to OFF but I managed to condition myself to it on the LG L6 (again brightness above the PWM level at all times on this) - I only have comfort view set at night rather than all the time so I'm trying that on the ipad.
Its almost like on IPS screens colors are too 'bright' regardless of brightness settings and using software to dull colors doesnt work, however reduce white point on IOS DOES help.