I got eye strain from my iPhone 3GS, 4S, and slightly from my 5S. My 6S however is not really a problem.
Ipad-wise, I got eye strain from my iPad 1,2 and 4, but not really with my Air 2 (I still get a little with extended use).
I've never related any of this to the OS - at least in my case.
What they did to iOS 7.1.2 on the iPad 4, they didn't on the iPhone 4. If I want heavy eye strain within seconds, I just have to upgrade my old iPhone 4 which currently runs on iOS 6.0.1. I tried it multiple times to be sure. Luckily one can downgrade iPhone 4. This is absolute proof that this issue exists. Maybe another factor is the type of the device's screen. We know Apple gets their parts from multiple manufacturers.
This is really puzzling. I am trying to find a pattern to see what could be the cause of these eye strain, but it seems that many people have different level of eye strains and are affected by different causes of eye strain.
The only way to find a pattern (and hence the cause) is for everyone to provide a background to what they get eye strain from, what devices they get eye strain, what devices they can use without eye strain, and other health/eyes related details. Only then maybe we can find a pattern and determine the cause. Otherwise it is hard to make sense of all of this.
We need someone or some university to do a research paper on this, so that they can go through detailed historical background of people who suffer from these eye strain, and record the devices/technologies that causes eye strain to certain people, and see if there is any solution that can be found. If they can identify the cause (or all the causes of eye strain) is also good already.
Kray We need someone or some university to do a research paper on this, so that they can go through detailed historical background of people who suffer from these eye strain, and record the devices/technologies that causes eye strain to certain people, and see if there is any solution that can be found. If they can identify the cause (or all the causes of eye strain) is also good already.
I have lots of underlying medical records dating back from when I was born about eye/brain injuries, etc. But I never had the strain until 2011. In fact I remember when I was younger hearing my mother talking about how harsh the flicker was from fluorescent lights and calling her "crazy" because while I could see it, it never affected me bck then. 
My iPhone 6s is the worst device I own
My mom's iPad Air running iOS 9 is the best iDevice I have used apart from an old iPod Touch I have which runs iOS 6
Ipad mini 2, 3 only
ipad air 1
ios 7 if you can find it
ios 8 otherwise
less preferred ios 9
ios 10, i will not buy the above devices with ios 10
ipad air 2, ipad mini 4 and the successors are just different, made more towards pleasing the crowd with better numbers on performance, thinner, better looking colors yada yada whatever to sell it, while sacrificing the picture quality, performance. ipad mini 2, 3, air 1 have just better picture quality, not messed with, not as manipulated,
ipad air ios 10 - no problems
what about the new IPAD PRO 9.7 ? i need a new tablet, my ipad air 1 is getting old.
iPad Air is 3 years old, iPad Air 2 is 2 years old. I assume me and Riktor are referring to the iPad Air 1 (at least I was in my post) but your point still stands. This tablet is snappy and performs its functions reasonably well. The biggest limitation is that it has half the RAM of the iPad Air 2. For me this only becomes an issue if I have a large number of tabs open.
got the new Ipad Pro 10.5 in post today.
while i run the setup, i became headache and eyestrain 
shit - already got case and screenprotector.
now i have to send it back.
so my old IPAD 1 is still the best.
the refreshrate is higher, but the motion blur is higher too than my old ipad air 1. cheap screen.
I tried both of the previous model of iPad Pros and found them to cause mild headaches. The iPad Air 2 is the best I've found. Not perfect but somewhat tolerable.
I've yet to check out the new model Pros.
I stopped even trying to use iPads after the iPad2. Which yes, is now 5 years old.
I heard a rumor that the new ones were ok, but the first Air as well as the iPad4 were BAD for me, that's pretty much where I threw in the towel.
My son has whatever the first one to use Lightning was... and it's almost usable, much like an iPhone 5 is almost usable.
has some tried the new IPad - non pro ?
I can use an iPad 2 and an iPad 3 ONLY with a Techarmor matte anti glare screen protector. With that on, zero eye strain. With it off, instant eye strain. I have never been able to determine what it is doing to the display to make it tolerable
i have tried the "old" ipad pro 9.7 - headache after 2 min.
then ordered the new IPAD 9.7 (normal, the cheap one). better then ipad pro, but still get problems with it.
now my beloved ipad air 1 stuck in recovery mode after trying to downgrade from IOS11 beta and i cant use it anymore
maybe i will order the old Air 2.
ensete I find it interesting that there are definite camps in iPhone land. There are those who could tolerate anything up to the iPhone 4s and iPad 2... and find the iPad 3 and iPhone 5 to be uncomfortable and the iPad 4 and iPhone 6 to be downright excruciating... that's the group I fall into. But there are others such as yourself for whom even the iPad 2 (and presumably iPhone 4/4s because it's the same display tech) were problematic.
My suspicion? I'm not actually sensitive to Retina displays in particular but in SOMETHING they started doing with CERTAIN retina displays. The fact that I can use my GF's iPhone 7+ for brief periods with NO brightness modulation and NO blue-light reduction and NO matte protector, and that I can use my buddy's iPhone 7+ with a matte protector for long enough to fiddle with an app, take a picture... means that these displays are all very different.
me again.
ipad air 2 - poor screen
reactiviated my ipad air 1 again. tried some other tablets from lenovo but still get problems.
