Electronic sunglasses darken a spot between your pupils and any glaring light source, like the sun, to make you safer, more comfortable, and more effective. This unretouched video of a functioning prototype is responding to an off screen glare source as well as its reflection.

The effect of wearing glare-shielding glasses is shown in the two videos below.  The video on the left has the glasses turned on, the video on the right has them turned off.  Without the shielding, much less can be seen.  What the video fails to get across is the physical pain of looking towards the sun, because neither the camera nor your computer screen can handle such high brightness levels.