Floaters are small, shadowy shapes that drift across your field of vision. They are caused by tiny clumps of gel or cells inside the vitreous humor, the clear gel that fills the inside of the eye. As light passes through the eye, these clumps cast shadows on the retina, which is the light-sensitive layer at the back of the eye. Most floaters are harmless and are a common part of aging. However, a sudden increase in floaters, especially if accompanied by flashes of light or a loss of peripheral vision, may indicate a more serious condition, such as a retinal tear or detachment, and should be evaluated by an eye care professional.