Fillers (like restylane, perlane, radiesse, juvederm by Dr Young in Bellevue near Seattle, WA) in the tear trough can theoretically lead to blindness but there are precautions that you can take to prevent it. The veins around your eyes and nose and center of the face are valveless and do not prevent particles from traveling back into the deeper tissues like your eyes and brain. It is possible to cause the particles that are injected with fillers to go back into the eye to cause blindness. But this is extremely rare. You can take some precautions to prevent this though. When you inject, you should not apply to much pressure with injecting. Also when you inject it you should never be in one place and your needle should always be moving and distributing the filler evenly. This prevents a load of filler being place in one spot and in the case that you are near a vessel the one spot is not being filler aggressively and possibly back into deeper structures like your eye. Also local anesthesia prevents the vessels from being injected by constricting the vessels so that it is less likely for the filler to get into the vessels. This is a video on fillers around the eyes.
Thanks for reading, Dr Young
Dr Young specializes in Facial Plastic and Reconstructive Surgery and is located in Bellevue near Seattle, Washington