"Eye floaters" are deposits or condensation in the vitreous jelly of the eye. People use the term eye floaters to describe seeing floating spots within their vision when they look around. Eye floaters may be present in only one eye or both eyes.
Why do people notice eye floaters?
The structures in the front of the eye (the cornea and lens) focus rays of light onto the retina. Light focused onto the retina allows one to see. The light going to the retina passes through the vitreous humor, which is a jellylike material that occupies the back two-thirds of the eye. At birth and during childhood years, the vitreous gel is usually totally clear and transparent. Later in life, strands, deposits, or liquid pockets very commonly develop within the vitreous jelly. Each of these strands casts a small shadow onto the surface of the retina, and these shadows may be perceived by the patient as eye floaters. As the eye moves from side to side or up and down, these strands, deposits, or pockets also shift in position within the eye, making the shadows move and appear to float or undulate.
What do eye floaters look like?
People describe eye floaters as spots, straight and curved lines, strings, or "O" or "C"-shaped blobs. Some people see a single floater while others may think they see hundreds. The lines may be thick or thin, and they sometimes appear to be branched. To most people, they appear grey and darker in color than the background. The density of different eye floaters will vary within an individual eye. Eye floaters may be more noticeable under certain lighting conditions and be more apparent when looking at a bright sky. Floaters are rarely seen in situations with reduced illumination.
Like fingerprints, no two people have exactly identical patterns of eye floaters. If a person has eye floaters in both eyes, the pattern of the eye floaters in each eye will be different. In any eye that has eye floaters, that pattern of eye floaters may also change over time.
Eye floaters always appear darker than the background and cannot be seen in darkness or with the eyes closed. This is unlike flashes, which often are seen in the dark and with the eyes closed.