Can the IPhone 5 be bad for your eyes?

I take a welding class at school. When we were In a different class and had nothing to do, my buddies and I were messing around with our welding shields. Most of us have auto darkening shields. They have sensors that detect really bright lights (like a welding arc) and then it darkens for the protection of your eyes. We were shining all our phones flashlights in front of the shields to see if they would darken. The bright LED Lights didn't trip the darkeners on most of our shields. Then the guy with the iPhone 5 tries his phone. The flashlight made all of our shields darken. But so did the regular home screen. On all of them. Our shield settings were standard for MIG Welding. His brightness was all the way up but still. If your phone can make a welding shield darken, that can't be good for the users eyes. Are they safe to use? No other phone could do this. Not even iPhone 4s

I don't think it is an issue.