Factors Associated with Pain Following Intravitreal Injections

To investigate factors associated with pain intensity following intravitreal injection and factors that might be associated with changes in pain intensity in patients who received repeated injections. A total of 172 eyes (147 patients) were prospectively enrolled. Patients rated their pain from 0 to 10 using a visual analogue scale. Multiple linear regression analysis was used to evaluate factors associated with pain score. Sixty-eight patients evaluated their degree of pain more than once and were divided into three groups according to changes in pain during repeated injections. Clinical factors were compared among the three groups. Pain scores of women (women, 3.1 ± 1.5 vs. men, 2.4 ± 1.2; p = 0.003), those who received dexamethasone implant injection (dexamethasone implant, 3.5±1.1 vs. anti-vascular endothelial growth factor, 2.7±1.4; p = 0.028), and those who did not undergo anterior chamber paracentesis (ACP) (ACP, 2.6±1.3 vs. no ACP, 3.0±1.6; p = 0.047) were significantly higher than those of the other groups. On multiple linear regression analysis, only female sex and ACP were significantly associated with degree of pain. The waiting time during the second injection was significantly associated with change in degree of pain in patients who received repeated injections. Women were more prone to perceive pain, and the ACP procedure reduced pain during intravitreal injections. Most patients who received repeated injections felt that pain was similar or decreased compared to that experienced during the previous injection. However, increased waiting time might have been associated with increased discomfort for patients who received repeated injections.