What forms of UV radiation primarily cause snow-blindness and welder's keratitis?

The correct response is based on the understanding of different forms of ultraviolet (UV) radiation and their specific effects on the eyes. Snow-blindness and welder's keratitis are primarily caused by UV-B radiation. This type of radiation is particularly harmful because it has a wavelength that corresponds closely to the cornea's sensitivity, leading to damage when the eyes are exposed, especially in reflective environments such as snow or during welding activities without proper eye protection.

UV-A, while present in sunlight and contributing to some ocular conditions, is less associated with the acute effects seen in snow-blindness and welder's keratitis. UV-C, although highly energetic and capable of causing damage, is mostly absorbed by the Earth's atmosphere and does not significantly contribute to these conditions. Visible light does not cause the keratopathy associated with UV exposure, further underscoring the specific role of UV-B in these situations.