Hit up Google, tons of good reading, there are many factors to consider... Also hit up the FDA warning label laws as they are informative as well...
Color
Power output
Exposure time
They all come into play... I know for a fact that there are a ton of articles that detail the potential for harm in detail... I did a bunch of research before I made the final decision the include a real laser pointer in my Proton Gun light kit, and found out that for the most part the red consumer laser pointers (Class IIIa) are nearly harmless... The chance of permanent harm from them is insignificant unless the perfect circumstances are created... And when I say created I mean just that they most likely will never happen, the exposure time to the eye needed to cause damage (1,000 seconds) is well in excess of the time between your eyes natural blinking... Ad to that the eye and laser would have to remain static and not move one bit with the laser exactly focused on the same location of the eye for this period of time... So short of your eyelids being forced held open for 16+ minutes, your eye movement totally immobilized and the laser held perfectly still and being viewed through magnification, permanent damage from a Class IIIa laser is a no go... But, this is only in regards to Class IIIa lasers...
Class I and Class II are considered harmless to the human eye...
It's not until you get the Class IIIb that you have to really worry about eye damage...
Class IV causes all sorts of damage, including fires...
Most of the negative publicity of "you will blind yourself" is simply over exaggerated urban myth and media hype... That is until you reach the Class IIIb level...
