Agree, at those power levels and wavelengths, a few millisecond bounce off a reflective or semi-reflective surface into your eye and your retina is toast.Putting a high-milliwatt green laser in the hands of a young experimenter is like giving a monkey a loaded pistol; he's going to hurt himself or others for sure.
"Due to the very small spotsize on the retina, a 40 mW HeNe laser can produce an irradiance on the retina of about 10 kW cm-2. Such an irradiance causes almost immediate thermal damage of the retina by denaturation of proteins, comparable to boiling of egg-white. Short-pulsed lasers with their high peak powers can cause optical breakdown and mechanical damage of the retinal tissues due to shock waves, which also often result in haemorrhage, i.e. a hole in the retina and bleeding. Injury statistics identify short pulsed lasers, particularly q-switched Nd:YAG lasers, as the type of lasers which caused the most frequent and most serious eye injuries [Rockwell 1999]. Even minimal retinal lesions may result permanent serious vision loss, especially if the damage is located in the centre of the retina. A fundus photograph with several types of retinal injuries in a rhesus monkey eye is shown in figure 2."Figure 2:
A range of injuries induced with a Nd:YAG laser on a monkey retina. The white spots in the centre are thermal burns, i.e. coagulation of retinal layers. With larger energies, holes in the retina are produced which result either in bleeding into the vitreous (the gel-like substance which fills the centre of the eye ball), or the bleeding is contained in the layers of the retina, which results in functional loss in the affected area.