The main causes of eye floaters, or small moving shapes in a person's field of vision, are small flecks of protein called collagen, according to WebMD. Other less common causes include eye injury, diabetic retinopathy and eye disease.
As a person ages, the collagen in the back of the eye can become shred-like, according to WebMD. When this occurs, accumulation of shredded collagen sometimes causes the vitreous humor, or gel, to move away from the retina, resulting in floaters. Eye disorders and diseases occasionally associated with floaters include retinal detachment, retinal tear, vitreous hemmorhage, retinal inflammation and eye tumors. Migraine headaches can cause a person to see floaters as well.