circular floater when the vitreous detaches from its annular ring surrounding the optic nerve
hundreds of tiny black specks is suggestive of a vitreous hemorrhage, resulting from disruption of a retinal vessel caused by a retinal tear or mechanical traction of a vitreoretinal adhesion
a few hours later, cobwebs may develop due to formatio of irregular blood clots
consider transient smartphone blindness due to only using one eye to look at smartphone in dark bedroom resulting in transient blindness while both eyes take time to adjust to a subsequent change in ambient lighting