Pretty interesting stuff right here. Basically a chemical agent based on plant material is added to the eye via a mixture of saline and a permeability enhancer. The end result is substantially improved low-light vision.

Chemically-Induced Night Vision:

However, in recent years other uses for ce6 have been found, the most notable in this case being its application into the conjuctival sac of the eye as a means of treating night blindness and improving the dim light vision of those with visual disturbances. This preliminary study attempts to test the ability of a mixture containing Ce6 to improve the dim light vision of healthy adults.
http://www.sciencealert.com/scientis...h-night-vision

http://scienceforthemasses.org/2015/...esting-photos/

http://scienceforthemasses.org/2015/...ng-chlorin-e6/