I started seeing a thin black floater when i turn my eye today. i normally have floaters but they are stable. i am very nearsighted. when should i see a doctor?

If new symptoms : Floaters are quite common and usually harmless ,and are due to a change in the vitreous, a gel like substance , in the eye . However , if they increase suddenly with blurring of vision , or eye pain or you see dark shadows , and also if you have a history of eye injury or diabetes , you should seek medical attention as they might indicate a retinal problem like a tear or detachment .