Effect of Alkalinised Versus Non-Alkalinised Peribulbar Anaesthesia on Ocular Akinesia in Cataract Surgery: A Randomised Controlled Trial

Abstract Purpose To evaluate the effect of alkalinised versus non-alkalinised peribulbar anaesthesia on the onset and duration of ocular akinesia, injection pain, and the requirement for supplemental anaesthesia in patients undergoing cataract surgery. Methods A prospective, double-masked, randomised controlled trial with 224 adults (≥ 40 years) scheduled for cataract surgery at two centres in Nigeria. Participants were randomised (1:1) to receive a peribulbar block with either an alkalinised mixture (2% lignocaine with adrenaline, 0.5% bupivacaine, and 7.5% sodium bicarbonate; n = 112) or a non-alkalinised mixture (n = 112). Ocular motility and anaesthesia were assessed at 2, 5, 10, and 15 minutes post-injection. Primary outcomes were the time to achieve surgical akinesia (score 0–4) and patient-reported injection pain. Results The alkalinised group achieved higher rates of successful akinesia at 2 minutes (75.0% vs 58.0%; p < 0.001) and 5 minutes (94.6% vs 78.6%; p = 0.029). Mean injection pain scores were significantly lower in the alkalinised group (3.50 ± 1.5 vs 4.7 ± 7.3; p < 0.001). While total surgical duration and supplemental anaesthesia requirements (3.6% vs 5.4%) were comparable, the alkalinised group demonstrated a significant delay in the first request for post-operative analgesia (p < 0.001), with 57.1% requiring relief only after 120 minutes compared to 24.1% in the control group. Conclusions Alkalinisation of the peribulbar anaesthetic mixture significantly accelerates the onset of akinesia, reduces injection pain, and prolongs the period of post-operative comfort. These findings support the routine use of sodium bicarbonate as an adjuvant to optimise surgical workflow and patient experience. Trial Registration: Pan African Clinical Trial Registry; ID: PACTR202212745220111.