Randomized Safety and Feasibility Trial of Ultra-Rapid Cooling Anesthesia for Intravitreal Injections

Abstract

To test the safety and preliminary efficacy of rapid, nonpharmacologic anesthesia via cooling for intravitreal injections. Single-center, randomized phase 1 dose-ranging safety study (ClinicalTrials.gov identifier, NCT02872012). Adults 18 years of age or older with a diagnosis of exudative macular degeneration or diabetic macular edema requiring bilateral anti-vascular endothelial growth factor therapy were included. A handheld device was developed to provide anesthesia via cooling to a focal area on the surface of the eye before intravitreal treatment (IVT). In 22 patients undergoing bilateral IVT, 1 eye was randomized to receive standard of care (SOC) lidocaine-based anesthesia and the other eye received cooling-anesthesia at 1 of 5 different temperatures and cooling times. Subjective pain was assessed via the visual analog scale (VAS; range, 1-10) at 2 time points: (1) immediately after IVT and (2) 4 hours after IVT. Treated eyes were assessed for ocular safety 24 hours after IVT. We determined the occurrence of adverse events in eyes treated with cooling anesthesia. Mean VAS pain scores immediately after IVT and 4 hours after IVT in eyes receiving cooling anesthesia were compared with eyes receiving SOC. A total of 44 eyes were treated, 22 with cooling anesthesia and 22 with SOC. No dose-related toxicity was found with cooling anesthesia. Mild, transient adverse events were recorded in 32% of patients treated with cooling anesthesia versus 44% of patients receiving SOC. The mean±standard error of the mean (SEM) VAS pain scores immediately after intravitreal injection were 2.3 ± 0.4 for patients receiving SOC and 2.2 ± 0.6 in patients receiving -10° C cooling anesthesia (P= 0.8). Mean±SEM pain scores 4 hours after injection were 1.6 ± 0.4 for SOC and 1.2 ± 0.5 in the combined -10° C arms (P= 0.56). Total mean±SEM procedure time was 124 ± 5 seconds for patients treated with cooling anesthesia versus 395 ± 40 seconds for SOC (P < 0.0001). Ultra-rapid cooling of the eye for anesthesia was well tolerated, with -10° C treatment resulting in comparable levels of anesthesia to SOC with a reduction in procedure time.