Well actually, administration does play a part if you think about it.
The more meth you have in your system, the more chance your pupils are going to be dilated due to the stronger vasoconstriction. While, this works in theory I also find it to be true, everytime I banged meth my pupils would be dialed like saucers..while orally and snorting did barely anything to them.
However, some people do seem to be particularly sensitive to pupil dilation regardless of amount used/administration. But I'd say these are a minority, high doses of methamphetamine are well known to cause large pupils due to the drugs constricting actions.
