Black spots in the field of vision are typically a type of floater, which may be a symptom of retinal detachment, diabetic retinopathy, retinal tears or severe nearsightedness, according to MedicineNet. Inflammatory diseases, such as syphilis, sarcoidosis, tuberculosis and acute retinal necrosis, may also cause floaters. They are more likely to develop after a cataract surgery, eye injury or YAG laser surgery.
Floaters move around the field of vision and may appear as black or gray spots, cobwebs or strings, Mayo Clinic states. Floaters seem to move away when the person tries to focus directly on them, and they may eventually drift out of sight. Looking at a solid, bright surface, such as a white wall, makes floaters more visible. Floaters are often linked to aging as debris forms in the vitreous gel that helps the eye maintain its shape. The vitreous becomes more liquefied and starts to detach from the inner wall of the eye, causing stringy fibers to clump together and cast shadows on the retina. The debris also partially hinders light passing through the eye.
Floaters that aren’t related to aging may be caused by posterior uveitis, a form of inflammation, Mayo Clinic notes. A person who suffers blood vessel damage or an eye injury may have floaters caused by internal bleeding in the vitreous. Doctors advise people to seek medical attention if floaters suddenly increase, they experience flashes of light or darkness clouds their peripheral vision.