Actually, it looks like there is lots of black pigment in that geckos eye. Same with all the other xanthic pictus I've personally seen, and even the ones on google image search. So to me, seems like the term "Xanthic" (which is a derivative of the term Xanthin - or yellow/orange pigment) was a good choice. Perhaps "Hyper-Xanthic" would have been a better name just to be more clear.

Great eye shot here: http://gexmart.tripod.com/sitebuildercontent/sitebuilderpictures/mine01.jpg