> the more directed the light source the more damaging for retinas (all other things being equal). Yes certainly, but in the real world the human blink reflex

> the more directed the light source the more damaging for retinas (all other things being equal). Yes certainly, but in the real world the human blink reflex means that all other things aren't equal. If you walk past a shiny glass building, you might catch a reflection of sunlight but only for a brief instant. Turn another direction and you'll see another shiny building, but you probably won't get a sunlight reflection off that shiny building because the angles are different and the sunlight is being reflected somewhere else. You can walk around a mirrored city all day and your eyes will be fine. But when you're surrounded by diffuse reflectors, now can't turn away from that reflected light. A city of pure white reflective buildings would be likely be quite painful on a bright day.