I have had Maalox dumped into my eyes on many an occasion and haven't suffered any ill effects, but maybe if I become addicted to throwing rocks at cops it'll start to take its toll.
But I can also say with certitude the thing that will probably deal horrible long term damage to your eyes is repeated untreated exposure to all the fun varieties of tear gas the police have. Rinsing with bottled water or LAW is going to do far less harm than that so I wouldn't discourage anyone from it.
Eagles are fucking bastards. Vicious pidgins with legal protection.