Can a dermal filler injection under the eyes damage the eye muscle or nerve? I had Belotero

Good afternoon,What you are describing is not considered a normal negative side effect now that any potential swelling should have resolved.  In addition, having difficulty opening the eye or any signs of infection should be immediately evaluated by the person that performed the injection.  Using filler in the tear trough area is generally a very safe procedure with a pleasing outcome.  However, technique and product choice go a long ways in making sure that the treatment plan is successful. Cannulas do not ensure proper placement of filler - the injector does.

This is difficult to answer without pictures and needs an in-person evaluation. If necessary, Belotero can be reversed with hyalruonidase. It may take a series of treatments. I recommend injections with cannulas to avoid complications. Rarely can superficial injection of the eye filler cause any issues internally with the eye. Likely this is not from the filler and is frank bad luck.  See an expert. Best, Dr. Emer

Difficult to answer your question without proper eye examination. Discuss with your doctor and see an oculoplastic specialist.