Ha!
This is funny! Not that your headache is a laughing matter, but the following coincidence:
About a year ago I posted somewhat humorous and hyperbolic take on EVFs here. This is a part of what I said:
I don't get it, not to make light of a health related problem, because I had a detached retina about 6 years ago and some screens give me fits, especially the new two new 27" imac I bought.
I dunno, I'm used to working around the limtations of a camera and viewfinder.
I just finished a large project where I worked RED evf's, gh4's, leica and contax ovf and other than the first few seconds of realizing what to expect from the viewfinder it takes me no time to adjust.
In fact it's not the finders I have to adapt to, it's the lag time, some evf cameras like the olympus are lightning quick, some ovf like my contaxs I know there will be some lag and adjust.
It's always been that way.
I guess what I don't get is the whole world seems to spend 85% of their waking hours staring at some screen, for work and play and doesn't seem to mind, but stick one in a camera and some purists just lose their mind.
I think there is room for both for different reasons, even in one camera since most cameras produce a live view image anyway, why not have a clip on finder like the oly ev4 that allows you to use efvs with the mirror up, or ovf with the mirror down.
We're so close to having cameras that can really and truly cross from motion to stills in one click of switch or a module and not ones that take twenty four add ons and a $15,000 stabalizer to make work.
evf's will lead the way to some amazing imagery that just wasn't possible before, like drones, stabalizers, remote mounts. This is coming more commonplace per day and I see a time where the possibilities are just endless.
The only real gripe I have is the lack of standardization. I'd love to see a show of hands of photographers that would like one standard menu system for all cameras, because if anything gives me a headache is remembering what button and trackpad, moves what to where to add a setting.
Anyway, I hope you work it out with your gh4 because I know eyes problems are a b**ch.
IMO
BC