It is symbolic that the man who designed replicant eyes shows the replicants the way to Tyrell. Eyes are widely regarded as "windows to the soul", eye contact being a facet of body language that unconsciously demonstrates intent and emotion and this is used to great effect in "Blade Runner". The Voight-Kampff test that determines if you are human measures the emotions, specifically empathy through various biological responses such as fluctuation of the pupil and involuntary dilation of the iris. Tyrell's trifocal glasses are a reflection of his reliance on technology for his power and his myopic vision. Roy eye gouges Tyrell with his thumbs while killing him, a deeply intimate and brutal death that indicates judgement of Tyrell's soul.