Many people see floaters or black spots. In most cases, these are harmless opacities in the vitreous body of the eye. However, they can also be a symptom of retinal tears or holes or even retinal detachment. If you also begin to see flashes, experience a sudden increase in floaters, these floaters move independently from your eye movements (as in a sudden shower of black dots across your field of vision), or you experience a shadow or curtain effect across part of your visual field, your should seek emergency treatment by an ophthalmologist immediately.