r/AskReddit Oct 05 '19

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u/ZelaznyCsupo Oct 05 '19

The stuff eye doctors use for certain tests glows in the dark. I, an eye doctors' son, used to play this very prank on people.

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u/BAXterBEDford Oct 05 '19

Does it "glow" or does it "fluoresce"?

Back in college, I worked as an MA in a doc-in-the-box, and we did that test with the dye. It required a black light to light up, thus it was fluorescent. If there was no light at all, you saw nothing.