Some ufologists have noted that the eyes of the commonly depicted "Gray" alien would be anatomically impossible, if spherical like human eyes; there simply wouldn't be enough room in the skull, no matter how outsized. It's worth recalling that an ostrich's eye is actually larger than its brain.
Then again, the familiar ink-black "eyes" may not be eyes in the familiar sense. If the Grays are physical beings, perhaps the eyes (with their now-famous black coverings) could be convex lenses -- a sort of alien "heads-up" display. In any case, I'm virtually certain the excessively stylized alien face so common in the media is an exaggeration, an easily communicable caricature.
Whatever the nature of the archetypal alien encounter, I'm convinced there's an hallucinatory component at play, an idea I plan to revisit in future posts.
Mac Tonnies