[Yoda]That is why you fail.[/Yoda]
I've been saying it for ages, but if you can't be bothered to learn about F1, or to read articles (even the basic, initial reports) about this accident specifically then why bother trying to contribute to an F1 thread? It's not like I have a vendetta against you, or dislike you personally, but nearly everything you ever write with respect to Formula One is utterly wrong.
Just so you know the visor didn't come of his helmet until well AFTER he'd come to a stop. The spring hit his helmet ABOVE, and to the left of, the eye aperture. The material was able to withstand the impact (change of momentum) and spread it over a larger area thus reducing any internal force spikes (although the shock of impact was enough to knock Felipe unconscious). However, the deforming structure did move enough to break his skull in one or more places, before (or possibly during) his brain hit the inside of his skull in around the same place. Damage to cells, veins and capilliaries and skin, plus the basic reaction of a living body after an injury, caused the swelling that currently impedes his vision.
If you didn't know any part of that then you shouldn't be bothering to talk about the accident or subsequent changes in the name of safety in an F1 thread. Except perhaps on a childs' forum.