Effect of fentanyl versus buprenorphine on the pupil size in phacoemulsification cataract surgery

BACKGROUND: Despite several recent innovations in phacoemulsification surgery, importance of pupil diameter in this surgery is becoming more evident. PURPOSE: To compare the effect of opioid agonist (fentanyl) versus opioid agonist–antagonist (buprenorphine) on pupil diameter in cataract surgery and to choose the best opioid in high-risk phacoemulsification surgery. METHODS: In this randomized double-blinded clinical trial, 60 patients who were candidates for elective phacoemulsification surgery were randomly divided into two equal groups: experimental (buprenorphine, 0.3 μg/kg) and control (fentanyl, 1 μg/kg). Pupil diameter was measured preinjection and at several times postinjection. Blood pressure was recorded at several intervals, as well as shivering, nausea and vomiting, and recovery time. RESULTS: Mean (SD) recovery time was significantly less in the control group (19.46±5.43) than in the experimental group (33.23±10.75) (P<0.0001). The constriction effect (ie, pupillary diameter in mm) was significantly lower in the experimental group (0.53±0.45) than in the control group (1.06±0.52) (P=0.0001). The percentages of constriction effect in experimentaland control groups were 7.68% and 15.07%, respectively. The eye was two times more constricted in the control group in comparison with the experimental group after induction of anesthesia. CONCLUSION: Buprenorphine is a better solution to decrease pupil constriction in comparison with fentanylinhigh-risk phacoemulsification surgery.