You'll recall how you'll have spots in your vision that are sort of the opposite effect of what you normally see. That kind of thing will happen if you look at the sun for an extended period of time. It'll feel a bit weird as your eyes recover from that. It doesn't mean you've hurt yourself. It's just that you've overloaded some of the photo receptors, and it takes a while to get back to full function. In most cases, it's going to be just a few minutes. There's no lasting damage from that. You would have to be staring at an extremely bright image for minutes at a time before you started to get any clinically significant damage.