You won't get blinded unless the laser hits your retina and stays there for a few seconds... if the laser is just passing and momentarily hits your eyes, you will regain full sight. But this is only true for 5mw-80mw lasers.. beyond 80mw, they may leave permanent damage even if it hits your eyes momentarily, but the chances of loosing full sight is low. The permanent damage may not even affect your sight, but much higher power lasers may leave you partially blind.
That said, many factors are involved here, the distance from your self and the laser, whether the beam is direct or a reflected beam, the rating of your laser, where it hits you on your eye and the amount of retinal exposure. Another huge factor is how concentrated the beam is for a particular rating; the sharper the beam, the more risk, and also huge distances causes many cheap laser beams to become unsharp, minimizing risks.
You have to understand your body is not a piece of plastic that once burned, nothing can be done, and is made out of cell's that keep reproducing which to a point can fix organs and body parts with time. Although, some areas of the body, if damaged, can never turn back to normal. If a laser hits parts of your retina, and if the exposure did not penetrate too deep, the chances are you will regain your sight, but maybe not as perfect as it was before. Retinal damage does not always mean blindness.
It's only when a laser hits your retina and penetrates so deep that the choroid also becomes damaged/or facess exposure, you may become partially or (if the optic nerve is damaged) fully blind forever. Also, the higher powered laser beams have the power to damage the lens, cornea and ciliary bodies, on the way to the retina. Depending on how the laser hits your eye, if the aforementioned areas are damaged and the retina does survive, your ability to focus or a blurred vision for life is a likelyhood.
With a laser below 150/100mWs the chances of permanent blindness or unrecoverable damage is near nill or very low when considering momentary exposure up to or less than quarter of a second. The truth is, no one has ever been permanently blinded by a publically purchasable laser due to an accident (this does not consider opticians using laser to correct vision) as the natural bodily response will be for the eye lids to shut minimizing penetration severely (There have been cases of change of sight). However, if you are stupid enough to shine laser in your eyes or other peoples eyes for a period longer than a quarter of a second, then you are also stupid enough not to be given a strong laser.
So your worry about accidental permanent blindness is very slim. However, damage may occur and not everyone is built the same. Young children however, should not be given such a laser as their natural reflexes are slower and accidents have a higher likely hood, especially when considering they are a curious lot who may want to experiment with the world around them.
Hope this has helped.
