The Eyes Have It

Eyes played a very crucial part in Bladerunner.  The Voight-Kampff test relied on checking the subject's eyes for pupil dilation to prove that the subject was not a replicant.  In this way the eyes became the one thing that could not be replicated perfectly in a machine.  They would always separate the human from the replicant so they sort of symbolized an intangible, indescribable part of humanity that some might consider the soul.  Another thing I noticed was that when Roy killed Tyrell, he put his thumbs into Tyrell's eyes.  I took this to mean that the human life is as fragile as the eyes and the replicant, and robots in general, are a threat to our humanity.  When Roy took the life of his creator, he sent a clear message that the coexistence of man and machine would not be possible.