Ever notice strange little shapes drifting across your vision? This common entoptic phenomenon originates within your own eyes. As an eye health expert, I'll break down what these are and why they appear.
A 2013 study of over 600 people found that 76% experienced these small floaters, with one-third reporting noticeable visual disruption. Known medically as myodesopsia—or simply "floaters" or "flying flies," they involve microscopic particles suspended in the vitreous humor, the clear, gel-like substance filling the space behind your lens.
These elusive shapes, often resembling tiny worms, are most visible against plain backgrounds like the sky, snow, or a white screen. Scientifically termed Muscae volitantes ("flying flies"), they aren't insects but typically bits of tissue debris, red blood cells, or protein clumps. As light passes through your lens, these particles cast shadows on the retina, producing the fleeting images we perceive.
Here's a video demonstration:
Another intriguing visual effect is the "blue field entoptic phenomenon," where tiny bright dots zip along winding paths in your field of view—especially vivid against a bright blue sky.
This is caused by leukocytes (white blood cells) flowing through the tiny capillaries in front of the retina. Blue light is absorbed by the more abundant red blood cells, creating shadow lines that your brain compensates for. Larger but rarer white blood cells don't absorb blue light, appearing as sparkling gaps in the blood column for brief, dynamic bright spots.
