Note though that near infrared also carries a risk of cataracts. I think they used to call it ‘glass blower’s eye’ because looking at the furnace was a high dose of near IR. Modern IR heaters use much longer wavengths.

Good point. I'm sure it has a lot to do with dosage and intensity. If near IR stimulates more activity in mitochondria (the purported mechanism here), that indicates there are some proteins or other compounds sensitive to that wavelength. It then stands to reason that large dosages at high intensity over prolonged periods can stimulate so much as to cause dysfunction, aka glass glower's cataracts.

I play around pottery kiln, you have to be careful looking at red hot stuff.

You usually don’t need to look at the light source as it penetrate the skin, clothes, skull, etc.