distortion (by viewing an image through a medium) n. refraction

[Literal examples would include looking at an object in water, looking through a microscope, rainbows, or a mirage over a hot road. However, the term is often used in figurative ways as well, as in this example.]  My mother was an actress, which added another refraction: I grew up watching her pretend to be other people. My great excitement at seeing her on stage was always tinged with a vague sense of being in limbo that would persist until I saw her again in her street clothes. (Kate Neuman, “When My Mother Forgot Me,” The New York Times, 06/21/2019.)

This word, when used in the above sense, can also be a synonym for illusion, mirage or hallucination.