You may sometimes see small specks or clouds moving in your field of vision. They are called floaters. You can often see them when looking at a plain background, like a blank wall or blue sky.
Floaters are actually tiny clumps of gel or cells inside the vitreous, the clear, jelly-like fluid that fills the inside of the eye. What you see are the shadows they cast on the retina, the nerve layer at the back of the eye that senses light and sends images to the brain.
You should see an ophthalmologist or optometrist right away if you suddenly develop new floaters, especially if they are associated with flashes of light. These symptoms may indicate a torn retina, which could lead to retinal detachment.