I've been taking 5-HTP as a supplement, and I've experienced mild visual changes- more trails/tracers, less structure, and in general more fluidity and dimension to my visual perception. Also, when looking in the same place for long periods of time (such as the floor, or someone's face) I see a lot more "light" energy, and what I'm looking at is not quite solid. Curious to hear your opinion as to whether slight visual fluidity and movement is the natural state of the eye. EDIT: sorry title got cut off it submitted too early. meant to say "the natural state of vision".
I believe the natural state of the eyes is for things to appear to overall look stationary and solid. From an evolutionary standpoint this would make sense as we can decipher movement and structure in animals that may be possible threats or prey, help us interact with each better and give us the ability to perceive various dangers such as things that are falling, utilize objects and perhaps it can be beneficial in even more subtle things such as being able to gauge weather patterns which can dictate how/when we find and provide shelter.
Interesting that 5htp is causing that for you. Are you sure it's that? The only noticeable effect I have had is better sleep, less sleep needed, overall more positive attitude due to increased energy. GB hit it on the head. Our minds have highly evolved filters to screen out "noise" in order to function. So in "normal" people I would say what you described is not natural. However the very slight increase in serotonin that taking 5htp causes shouldn't be causing what you're observing, at least as far as I know, which isn't a whole lot.