[mdeck_]

Blue LEDs and black lights show this effect very clearly. This is e.g. described much more succinctly in the top comment here: https://www.reddit.com/r/askscience/comments/3c1qsg/why_do_b...

> 2 reasons: 1) You don't have the nearly as many short wavelength detecting blue cones as you do red and green in your fovea. 2) The angle of refraction is dependent on wavelength and short wavelengths get refracted more than relatively longer ones by your eye and therefore focus in front of your retina if you are myopic (nearsighted). The black lights are throwing off a ton of very short wavelength light and when coupled with the larger pupil you have in the dark it sets your eye up for a bunch of chromatic aberration. They should look clearer if you are hyperope or overcorrected in your myopic prescription, or if you view them at a closer distance.