Here's my story..
I traded in my 6s for the IPhone 8 last week, I got the 8 for what seems like an excellent price (399$ after trade-in). While there, they tried to sell me on the Xr for (549$ after trade-in) but was reluctant mainly because of the size. Alas, after I used the 8 for a few days (No Eye Strain Issues) I kept thinking it wasn't much different from the 6s and decided to go back in and exchange it for an XR just to get something newer/different. I've now been using the XR for 3 days and have experience some eye issues.
Let me start out by saying I really like a lot of features on the XR (Camera & Battery Life) being the best, as just in a few days I can already tell a big difference between this and the Iphone 8.
With that being said, at times, something just seems off, I feel as if my eyes are working extra hard to focus against the white background. It almost feels as if I'm wearing the wrong contact prescription while reading text on the screen. My biggest issue is after use of the phone, I've found myself struggling to adjust my eyes back to normal, which is scary. I've messed with the true tone, night shift, text size, reduce motion and unfortunately something still seems off...
Something with the white background on this phone seems to have a weird hue to it, almost pinkish, I compared the screen to a 7-plus and the difference was quite noticeable. So while text messaging, I have found to have my biggest eye strain. I have no idea if this is causing my strain, but maybe?? Either way, it sucks, I want to love this phone, but am leaning towards heading back in and switching back to the 8 or trying the 8-Plus..