Floaters are a similar phenomenon. They are clumps of microscopic fibers in the jellylike vitreous humor of your eye, which cast a shadow on the retina. Floaters are a common occurrence as you get older, and are generally harmless, though they can indicate a retinal tear. The technical name for them, if you wish to impress someone, is muscae volitantes, or “hovering flies.” If you held a human eyeball in your hand, you might
