Q1. How is snow blindness caused in human?

Ultraviolet rays can cause damage to the eyes when they are reflected towards the eyes by certain substances, such as sand and snow. When this happens, the amount of UV rays the eyes are exposed to is increased. This fact is the basis of the condition photokeratitis, also known as snow blindness. Photokeratitis is sunburn of the cornea, and usually recedes within one to two days. It occurs when the eyes are exposed to large quantities of UV light in a short amount of time.