Occassionally I Get Blurred (floaters) In My Eye Sight.....it Seems

Occassionally I get blurred (floaters) in my eye sight.....it seems to happen when Im tired or stressed....I can see OK, but The floaters are often on the outdide of my field of view......It usually lasts about 20-40 minutes......It occurs about once every few months...but twice in the last 3 days.......I use reading glasses as full time glasses