The Scientist: Abdhish R. Bhavsar, M.D., a clinical spokesperson for the American Academy of Ophthalmology and senior and managing partner at the Retina Center Of MinnesotaThe Answer: If you’re seeing dark gray spots or strands that seem to be floating around in front of your face, what you’re actually seeing is stuff floating inside your eyes.The rear two-thirds of your eyeballs are filled with a jelly-like substance called vitreous that helps give your eye its shape and squishiness. The vitreous changes as you age, liquefying and often developing so-called opacities or vitreous strands, little bits of solid matter usually made of collagen fibers. They float around in the vitreous, blocking the light that comes in through your pupil and casting shadows on the retina at the back of the eye. Those shadows are what you think you see in front of you.They look like they’re floating in space because they are literally floating around in the vitreous. If you try to chase them, the shifting of your eyeballs will create minute waves that carry the debris to and fro. Keep your peepers still and the opacities may drift out of your field of vision.If you suddenly see an onslaught of floaters, or if they are accompanied by flashing lights or what seems to be a curtain closing across your vision, you should consult an eye doctor, as this could signal inflammation, bleeding or the detachment of your retina. The occasional elusive blur, however, isn’t worrisome.MORE:20 Foods for 20/20 VisionImprove Your Eyesight With Your MindEye Twitches, Explained