Eyeshine is the term used for the unusual luminous appearance of Richard B. Riddick's eyes. The condition is similar to tapetum lucidum, the structure that causes cats' eyes to appear to glow. It allows Riddick to see very well in the dark, but he is acutely sensitive to bright light. Riddick paid Cutter to perform a surgery to give him eyeshine. In Hunt for Riddick (the promotional minigame), it is suggested that Riddick was actually at Ursa Luna Penal Facility when he underwent the procedure. It is also stated in Hunt for Riddick that approximately 0.2% of recipients survive the procedure, and that 0.005% of recipients regain any vision at all.
Behind the scenes
In the game "Escape From Butcher Bay" it is suggested that these are a dormant Furyan trait — he has them appear while he's having minor wounds stitched up, not through a surgical eyeshine procedure. Riddick usually makes up the idea of how he received the eyeshine via Pope Joe, but in reality Shirah makes it known in the game that he has always had them. The Purifier does not have this luminous-eye trait, and the Furyan Shirah does not appear to have it either, there is also a speculation that Riddick has this trait because he is an 'Alpha Male' Furyan whereas The Purifier and Shirah are not.
In Riddick (film), Vaako tells Riddick that when the Necromonger Empire invaded Furya he saw a male furyan who took out several of their soldiers and his eyes where just like Riddick's. This gives indication that Riddick eyeshine is actually a Furyan trait only given to Alpha males.