Pain control and subconjunctival haemorrhage after intravitreal injection using cooled anaesthetic eyedrops and antiseptics: A prospective, double-blind, randomized controlled trial

Purpose: To evaluate whether cooled anaesthetic eyedrops and antiseptics alleviate pain and minimise subconjunctival haemorrhage following intravitreal injection. Methods: A prospective, double-masked, randomised controlled trial of 100 participants receiving either cooled (n = 50) or room temperature (n = 50) topical anaesthetic eyedrops and antiseptics before receiving an injection of bevacizumab. Baseline tolerability was estimated using a self-reported pain sensitivity questionnaire. Results: Overall tolerability was comparable between the study group and the control group (0.75 ± 0.13 vs. 0.74 ± 0.14, respectively, p = 0.99). Subconjunctival haemorrhage incidence was similar in both groups (80% vs. 86%, respectively, p = 0.113), as was subconjunctival haemorrhage size (2.75 ± 5.51 mm² vs. 5.53 ± 10.72 mm², respectively, p = 0.11). Sub-group analysis demonstrated that the participants taking daily ocular eyedrops who received cooled anaesthetic eyedrops and antiseptics reported less pain at 10 min and less burning sensation at 24 h compared with matched controls (0.67 ± 1.50 vs. 2.50 ± 3.03, respectively, p = 0.040 and 0.00 ± 0.00 vs. 1.44 ± 2.96, respectively, p = 0.045). Participants who received cooled eyedrops and did not use antithrombotic therapy had smaller-sized subconjunctival haemorrhages compared with matched controls (1.55 ± 1.87 mm² vs. 8.29 ± 14.61 mm², respectively, p = 0.038). Participants with hypertension who received cooled eyedrops had smaller-sized subconjunctival haemorrhage compared with matched controls (2.33 ± 4.99 mm² vs. 6.89 ± 12.41 mm², respectively, p = 0.045). Conclusion: The benefit of using cooled anaesthetic eyedrops and antiseptics to alleviate pain and minimise subconjunctival haemorrhage following intravitreal injection was not proven in the general population. It may be beneficial in part for some patients, such as those who regularly use eyedrops, patients with hypertension or those not on antithrombotic therapy.