Basically, as the title says. Is there a word to (best) describe someone who sees and remembers every single thing?
marked by or involving extraordinarily accurate and vivid recall especially of visual images; an eidetic memory
In the case of Marilu Henner (of "Taxi") she vividly remembers every day of her life. The phenomenon is called Highly Superior Autobiographical Memory - or, H-SAM. They had a documentary about her abilities recently.
Photographic memory would be close.
Hyperthymesia is the single word meaning Highly Superior Autobiographical Memory. Hope this helps!