Disabling glare comes in two forms, "background" from the sun flooding through windows and "spot" from dazzling on-coming bright car headlights.  Some patients are diabled more by one than by the other type of glare.  This new Glaremeter tester measures both types of glare, each by a flick of a switch: Flood to Spot/Spot to Flood.  Lens holder sold separately.  To qualify for cataract surgery due to glare, the level of  impairment must be documented.  Patented technology.  Consider 10 Year Extended  Warranty.