Is Evidence Theory Loaded?

We see things only when images of them appear on our retinas, and we do not perceive those images until they have given rise to electrical impulses in our nerves. The physical evidence that directly sways us is less than millimetric. When you hear the phrase, evidence is theory laden or something like that, this is one sense in which that phrase is cashed out. We did not directly perceive stars, spots on photographic plates, or other external objects or events. Or that because a photo detector at a certain position does not register a hit in weak light, there must be parallel universes?