Just a guess how this could happen with LED bulbs but not the sun: at noon, there is certainly more short-wavelength power in sunlight but if you're outside wit

Just a guess how this could happen with LED bulbs but not the sun: at noon, there is certainly more short-wavelength power in sunlight but if you're outside without eye protection your pupils are going to shrink down to limit retinal exposure. Out of the sun, your pupils can be open wider but the short wavelength light is still there with these LED bulbs. This is a pretty new development: humans have of course had artificial light sources since before recorded history, but flames (and much later, hot wires) had much less blue output than these specific LEDs they're testing. Another guess: they might actually find similar retinal problems from sunlight exposure in people who spend most of their working life outdoors, but since most people in developed nations don't work in agriculture anymore their baseline population doesn't reflect a lot of sunlight exposure.