Associated risk factors of postoperative pain after glaucoma surgery: a prospective study

Purpose This study aimed to determine degree of postoperative pain and the incidence of serious postoperative pain after glaucoma surgery and further to identify the associated risk factors. Methods A total of 194 consecutive patients who were diagnosed with glaucoma and underwent glaucoma surgery were enrolled in this study. The intensity of postoperative pain was evaluated using numerical rating scale (NRS) within 24 h after surgery; NRS >= 5 was considered as clinically significant postoperative pain. Risk factors associated with the development of postoperative pain were analyzed by multivariate logistic regression analysis. Results Clinically significant postoperative pain was experienced at any time after glaucoma surgery in 41.75% of the patients, which peak at 2 h. 27.8% of the patients requested analgesic medication within 24 h after surgery. According to multivariate logistic regression analysis, preoperative anxiety (OR = 4.13 [1.29-13.2], p = 0.017), cyclophotocoagulation (OR = 30.9 [3.47-375.1], p = 0.002), and phacotrabeculectomy combined with or without intraocular lens implantation (OR = 30.0 [2.69-335.6], p = 0.006) were associated with increased clinically significant postoperative pain. Interestingly, patients with diabetes and/or hypertension were associated with less postoperative pain after glaucoma surgery (OR = 0.23 [0.08-0.64], p = 0.005). Conclusion Patients undergoing glaucoma surgery tend to experience postoperative pain in the early postoperative period. Anxiety level and surgery types of cyclophotocoagulation and phacotrabeculectomy are risk factors for postoperative pain. Patients with diabetes and/or hypertension are less likely to develop postoperative pain.