[amluto]

As I understand it, it’s largely a focusing issue. Close to the visible range, a distant point source gets focused to a point on the retina. At 1550nm, the energy is deposited uniformly on the cornea unless the laser is focused to a tiny spot on the cornea.

edit: I don’t know to what extent this is relevant, but humans can regenerate the corneal epithelium. Think about all the sand you’ve gotten in your eye as a kid, and the fact that it probably didn’t accumulate enough damage to blind you.