You've been driving all day, and well into the night. Your eyes are tired, but you still have an hour or two of safe driving left in you. You slide carefully past a truck, checking your mirrors carefully. One last look - you're just about safely past - and *POW* - a stabbing pain as vision dims. You look forward, seeing more blue blur than road, blinking to try to recover sight.
This needs to end. Please, people, stop flashing your brights in our eyes.