Glare refers to difficulty seeing or a reduction of visibility in the presence of a bright light. Glare may be caused directly or indirectly by natural or artificial light. Common examples of glare include that caused by headlamps at night, overhead light reflected on a computer monitor, and driving into the sun at sunrise or sunset.
A light’s glare is quantified in terms of a G rating. As shown in the figure below, it takes into account the amount of lights in the FH, BH (60-80 degree) and FVH, BVH zones (80 -90 degree) (zones in the dotted red box). While some LED lights have a very high brightness (intensity), they do not produce more glare than that caused by halogen bulbs or similar conventional lights. Glare can be controlled by selecting a product or lighting design designed to direct light only where it is needed.