In terms of potential harm to human eyes, ultraviolet (UV) light is generally considered more dangerous than infrared light. Both UV and infrared light exist beyond the visible spectrum of light, with UV light having shorter wavelengths and higher energy, while infrared light has longer wavelengths and lower energy.
Excessive exposure to UV light can lead to various eye conditions and health risks. Prolonged exposure to UV radiation from the sun, for example, can cause damage to the cornea, lens, and retina, leading to conditions such as photokeratitis (sunburn of the cornea), cataracts, and an increased risk of developing certain types of eye cancer.
On the other hand, infrared light, particularly the longer wavelengths of infrared radiation, is less hazardous to the eyes. It primarily causes thermal effects, meaning it can generate heat and potentially cause burns or tissue damage if exposed to very high intensities or over prolonged periods. However, typical levels of infrared light encountered in everyday situations are not generally harmful to the eyes.
That said, it's important to note that both UV and infrared light should be managed and protected against to ensure optimal eye health. Wearing appropriate sunglasses with UV protection and using safety measures when exposed to intense sources of light, such as in industrial or medical settings, can help mitigate potential risks.