On: Can a Human See a Single Photon?

[kurtosis]

so I dug up the reference on this in case you are interested and have access to nature. Google scholar has pointers to the pdf

Aho AC et. al. "Low retinal noise in animals with low body temperature allows high visual sensitivity." Nature. 1988 Jul 28;334(6180):348-50.

http://scholar.google.com/scholar?q=aho+AC+nature+1988