Gurm Im also out of ideas on how measure such difference, and there must be one. All I can think of, that could put all the little variances in backlighting, pwm, software, glare into one bag, would be to very precisely measure how input into each eye differs (so two cameras, specific angles, very sensitive software to evaluate). And maybe then youd have nothing too. Its a topic for a whole scientific team composed of optometrists and developers who create this software. Hardly something that will be done for few hundred people like us. But I believe theyd find something.
However the heterophoria therapy seems to work. Ive recently tried a LAN gaming party, worried I might not last even one hour and go home with a lot of pain. Played on some gaming PC, monitor they had there, didnt check anything, I believe graphics were powerful Radeon card. I must say I stayed 4 hours, it was fun and I did feel some symptoms oncoming after an hour or so. Sometimes I just looked away from the screen for a few minutes and then could go on. It wasnt completely comfortable and I did not feel perfect afterwards, but after 2 more hours the discomfort passed and I was back to normal (my jaw popped loudly couple times, and I had tight muscles around head - all described here, same goes for horizontal heterophoria --in our case, understand it as when the phoria is triggered, as by a display/light-- - http://clarkeeye.com/wp-content/uploads/2015/04/Symptoms-of-Vertical-Heterophoria.pdf). Before the treatment I would have a suicidal headache for day after. So the therapy works, heterophoria is to blame for this issue, but of course noone knows if I can cure it 100% and for good. I hope its possible and seeing that more people get diagnosed here, I recommend you find a proper optometrist and get your convergence excess/insufficiency confirmed🙂
The therapy however takes a lot of effort, self-discipline and patience. Apparently not everyone is cut out for it, Ive been told Im doing way better than some simpler cases where the people are not that motivated as me even though their case could be cured way faster. Mine is established at about 8 months of 30 minutes daily. But hey, if thats what it takes to finally buy a new laptop...