possible eye problem

I haven't been here in a while, so hi everyone!

My boy Red gets pink eye on occasion, and after the last time I noticed his left eye "glows" even when the other one doesn't. At first I thought maybe the light was catching him wrong or something, but that's not the case. His vision seems fine though. Does anyone know what could be causing this?

Is Red having drainage from his eye? Does the pupil look different from the unaffected eye? Is his third eyelid showing at all? It may be a bacterial or viral infection in his eye - does the eye redness resolve on its own?

That almost sounds like a cataract, or maybe a herpes infection of the cornea...has the vet checked it out?