Efficacy of 4% tetracaine gel and lidocaine-prilocaine cream in reducing local anesthetic injection pain in upper eyelid blepharoplasty: a randomized, single-blinded, controlled trial.

[BACKGROUND] The injection of local anesthetics, an extremely painful procedure, leads to a reduction of patients' acceptance.

[OBJECTIVE] To investigate the efficacy and adverse reactions of 4% tetracaine gel (TG) and lidocaine-prilocaine cream (LPC) on reducing the local anesthetic injection pain for upper eyelid blepharoplasty.

[METHODS] Sixty participants were equally divided into three groups. Each patient in two treatment groups was assigned a pair of eutectic mixture of local anesthetics (EMLA) and 4% TG, and the blank control group did not receive any topical anesthetic. The primary outcome was the pain score associated with anesthetic injection. The secondary outcomes included the local cutaneous reactions and eyelid edema in 24 h postoperatively.

[RESULTS] The NRS score in the control group was 6.65 ± 1.60, in the 4% TG and EMLA sides of 5.75 ± 1.62 and 6.25 ± 1.48 in group A, without statistically significant (p = 0.334, 0.067, respectively). While in group B, the injection pain scores in 4% TG and EMLA sides were 4.65 ± 1.66 and 5.5 ± 1.73 (p < 0.001 and p = 0.031, respectively). A negative correlation was observed between age and LAIP (regression coefficient = -0.022), whereas gender had almost no impact (regression coefficient = 0.368). The administration duration of 4%TG and EMLA had no statistically significant effect on the cutaneous reactions observed on the patients' eyelids (p = 0.723, p = 0.507, respectively). However, the incidence of cutaneous reactions was 35% for EMLA, significantly lower than 72.5% for 4% TG (p < 0.001). The postoperative edema score of the control group was 1.5 (1.0,2.0), while in group A both 4% TG and EMLA sides scored 2.0 (1.0,2.0) and in group B they scored 2.0 (1.0,2.0) and 1.0 (1.0,2.0), respectively. Neither group showed significant differences in postoperative edema score compared to the control group, and there's also no significant difference was revealed comparing the 4% TG or EMLA side with the paired side in one group or the same side in the other group.

[CONCLUSION] In comparison to LPC, 4% TG showed a stronger anesthetic effect on reducing injection pain after 60-minute application. It also generally presented a higher frequency of cutaneous reactions but didn't affect the eyelid edema 24 h postoperatively.

[TRIAL REGISTRATION] This study was registered at chictr.org (the first registration date is 03/04/2023, and the registration number is ChiCTR2300070153).