A black spot in the vision of one eye is probably a harmless floater, but there can be a more serious cause requiring treatment.
Eye Floaters: Black Spots in Vision
A Black Spot in Vision of One Eye - CorneaCare
Eye floaters - Symptoms and causes - Mayo Clinic
Why You're Seeing Black Spots In Your Vision, black sites
Black spots - Miranza
Why You're Seeing Black Spots In Your Vision, black sites
White Spot on Iris of Eye - CorneaCare
Corneal Ulcers
How to get rid of brown spot on eye Discolouration, Pigment, Freckle, Pterygium
Why do you see black spots after looking into bright light? – VisionPal
Why Does My Eye Hurt when I Blink? - CorneaCare
Eye Floaters & Black Spots in Vision
8 Reasons You Could Be Seeing Black Spots in Your Vision - Magruder Eye Institute
If you see flashes, floaters, change of vision, or a curtain in front