Originally posted by: onix
This article makes things clearer, but doesn't answer my original question. My eyes (greenish-hazel) are pretty dark.
http://en.wikipedia.org/wiki/Red-eye
Is it possible for humans to have a "tapetum lucidum"?
Humans do not have a tapetum lucidum. I've never heard of any case of mutants having one, but maybe it's possible.
Also, doesn't pupil reaction time slow with age?
Pupil reaction time is age-dependent, but I'm not all that familiar with the literature regarding purely light-related pupil responses. The pupil diameter also changes with accommodation, and this response also varies with age. I'll speculate that the pupil reaction time will actually decrease with age, as it has been demonstrated that the ciliary muscle (from which the iris emanates) becomes stronger with age. The iris should do likewise if my reasoning is correct, and I believe this would imply a decreased reaction time.