What is welding flash?

The bright light generated by some welding equipment is very high in UV content.  And, just as too much UV outdoors can cause sunburn, so the UV light from welders can cause sunburn-like damage to the clear skin layer covering the front of the eye.  Sometimes straight away but  often a few hours after the welding flash, the damaged cells die and fall off, exposing the very sensitive, nerve-rich layers below.  The pain and discomfort is such that most people make sure they never get welding flash a second time.

A similar effect can happen by spending a bright sunny day at the snow without sunglasses.