- Edited
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.