As long as you use one of the cheap lasers rated under 5 milliwatts, eye damage is not an issue; several minutes of continuous exposure (laser aimed into the eye at close range, no blinking) is necessary for even minor eye damage. And handholding a laser directly on the eye for more than a fraction of a second is pretty much impossible, especially given the existence of blink reflexes. Of course, if you get a high-powered laser that can light matches and cut plastic and pop balloons, all bets are off, but a standard <5mW cheapie will work just fine and won't cause any injury to your subjects.