User blog comment:SayuriDarling/The Mark of Athena Official Discussion/@comment-4388405-20121006181920/@comment-4531192-20121006215326

It is never stated that the light glowing from Hera is "golden" -- it is described to be just light. White light, as in the portion of the spectrum that is visible to the eye, like what you see when you look at the sun. When Jason looked at Hera in her divine form, he saw a glowing ball of light. So why would his eyes glow gold?

But the real question to ask is, how could the Eidolons have possessed him then? When Hera turned into her divine form, every monster, wind spirit, et cetera, vanished from that hill. Heck, even that one giant ran away. So there is really no possibility of an Eidolon possessing Jason before or during that event.