The intravitreal injection pain study: a randomized control study comparing subjective pain with injection technique

Editor,

Increasing numbers of people require prolonged intravitreal anti‐vascular endothelial growth factor (anti‐VEGF) for retinal conditions (Stewart 2012), but the most effective peri‐procedural analgesia is uncertain (Shiroma et al. 2017). We compared the efficacy of two popular techniques, subconjunctival injection (SCI) with 2% lignocaine and topical pledget (TP) with 0.5% amethocaine hydrochloride, through a prospective, randomized control trial.

We consented all adult patients undergoing anti‐VEGF injections, prospectively over 12 weeks in 2014 at one tertiary centre hospital in Australia (n = 112). Research staff used block randomization, participants were not told of their allocated anaesthetic and the treating medical team was only aware on the day of treatment. All patients underwent a standardized approach to minimize confounders: two drops of 0.5% amethocaine hydrochloride, 1 drop of 5% povidone–iodine after 2 min, positioning of an eyelid speculum, the allocated anaesthetic technique and injection of similar volumes of anti‐VEGF, irrigation with 0.9% normal saline, and no antibiotics, eye pads or other pain relief. In the SCI group, 0.2 ml of 2% lignocaine was injected with a 30G needle as a subconjunctival bleb in the superior temporal region of the eye, followed by sterile precautions for 2 min and then anti‐VEGF injection. In the TP group, a cotton bud soaked in 0.5% amethocaine hydrochloride was applied to the superior temporal region for 30 s followed immediately by anti‐VEGF injection. Pain scores on a visual analogue scale (VAS) from 0 to 10 were recorded at 5 min and 24 hr postinjection over the phone using the same VAS. Sixty‐seven patients returned and underwent the opposite anaesthetic technique (SCI; n = 36, TP; n = 31). Patient withdrawal from the study, not requiring an additional injection within the study period and failure to attend appointments, limited studying the rest of the cohort. Pain scores at 5 min, 24 hr and patient preferences were collected.