Mydriasis induced by sub-Tenon's ropivacaine injection in patients undergoing strabismus surgery

Abstract

Purpose: To investigate the effects of sub-Tenon's capsule ropivacaine injection on pupillary diameter in strabismus surgery.

Methods: A total of 16 patients were randomly assigned to 2 groups. The ropivacaine group (R) received sub-Tenon's ropivacaine 1% (2.5-3 mL) injections. In the control group (C), general anesthesia was induced and a saline solution (2.5-3 mL) was injected in the sub-Tenon's capsule. Pupillary diameter was measured at baseline and 2 and 5 minutes from the injections. The effects of the injections were expressed as a ratio of final (5 minutes) versus basal diameter.

Results: A significant mydriasis occurred in the ropivacaine group when compared with the control group (Group R vs Group C ratio = 2.32, p < 0.0001) or with unoperated fellow eye (R vs unoperated eye ratio = 2.29, p < 0.0001).

Conclusions: Ropivacaine in the sub-Tenon's capsule induces a mydriasis probably related to a pharmacological ciliary ganglion block.