Below are some quotes from the literature- these low power laser pointers probably don’t pose a serious hazard even in the unlikely scenario were its pointed into someones open eye for an extended period of time- and more realistically its assumed such exposure will be short (0.25 seconds) because the victim would simply blink or look away.

http://www.ncbi.nlm.nih.gov/pubmed/11115266

We report the absence of photic retinal injury after exposing the retina to light from class 3A laser pointers for durations of up to 15 minutes. Three patients with uveal melanomas were scheduled to have an enucleation. Each agreed to have his or her retina exposed to laser light from a class 3A laser pointer prior to enucleation. Continuous exposure was directed to the fovea for 1 minute, to the retina 5 degrees below fixation for 5 minutes, and to the retina 5 degrees above fixation for 15 minutes. Ophthalmoscopic evaluation of the cornea, lens, and retina and fluorescein angiographic studies of the retina were conducted before, 24 hours after, and 11 days after laser exposure in the first case; before and 86 hours after exposure in the second case; and before, 96 hours after, and 15 days after exposure in the third case. Other than transient afterimages that lasted only a few minutes, we were unable to document any functional, ophthalmoscopic, fluorescein angiographic, or histologic evidence of damage to any structures of the eyes. Transmission electron microscopic studies of retinal sites targeted by the laser pointers in the second and third cases revealed ultrastructural abnormalities in the outer retina and the pigment epithelium that were similar to abnormalities seen in the retina approximately 8 mm away from the targeted sites. The risk to the human eye from transient exposure to light from commercially available class 3A laser pointers having powers of 1, 2, and 5 mW seems negligible.

http://bjo.bmj.com/content/82/11/1335.long

Laser pointers may be class 1, class 2, or class 3A, using the American classification; or class 1 or 2, using European codes of practice. Class 3A laser pointers classified under the American system will become 3B lasers under the European system, because they fail the irradiance test. If systems are designed to meet the European class 3A requirements the beam spreads so rapidly that the spot viewed on a screen would be so large that it would be unhelpful as a pointer. It is this differential between European and American approaches that has led to some of the media hype indicating that laser pointers fail safety tests, or exceed the levels indicated in codes of practice.10 It should be remembered that few laser pointers are manufactured in Europe and the majority come from the Pacific Rim and the United States. It should also be remembered that the major world market for laser pointers lies within the United States and outside the European Union. It is hardly surprising, therefore, that products which have the correct classification on leaving the point of manufacture may have an inappropriate classification on entering the European Union. In practice, class 3A systems classified using the American standard have an upper limit of emitted power of 5 mW, and remain safe, because of the blink reflex and aversion response. Clinically, between 100 and 500 mW (of emitted power) are required at diode wavelengths for retinal photocoagulation.

That said, anyone intentionally pointing lasers at a plane, no matter what their power, should be prosecuted as harshly as possible. Anything that distracts or TEMPORARILY blinds a pilot while landing a plane could be disastrous. Additionally, the actions of these idiots make my job harder…

Also, as I pointed out before, you can easily buy handheld lasers that are MUCH more powerful than 5mW… 100′s of times more powerful- these are VERY dangerous lasers. These lasers should be made illegal, but I want to buy a few before they are… 8^)

Cheap green laser pointers may be dangerous close up, because they work by generating much more than 5mW of 1064 nm light and then passing it through a doubling crystal to create the 5mW of green- if they dont have a filter to remove the 1064nm light then the power at the exit could be much more than 5 mW- much of it invisible. They are supposed to have a filter, but i have heard tales -possibly apocryphal- of some that havent…

As you pointed out – inadvertent exposure of aircraft is likely to be very brief…