We have all experienced that annoying glare that comes from a computer screen or oncoming headlights when driving at night. But what causes it and how can we avoid it? Glare occurs when you experience a discomfort or reduction in visual performance when the eye is exposed to an intensity of light that it has not adapted to. 

In other words when light is reflected into the eye at an angle and level that it is not ready for.  For glasses wearers it can be worse as the glare also occurs when light is reflected off the surface of the glasses lens and back into the eye. This can be debilitating and even dangerous in some situations such as when driving.