Effectiveness of Superior versus Inferior Subconjunctival Anaesthesia for Cataract Surgery

Abstract

This study compared the efficacy of two different injection sites for subconjunctival anaesthesia (SCA) in cataract surgery. One-hundred-and-three eyes of 99 consecutive patients undergoing routine cataract surgery were randomised to receive SCA either to the superior bulbar conjunctiva (n=52) or the inferior bulbar conjunctiva (n=51). Pain experienced during anaesthetic administration and at various stages of the perioperative period was assessed using a simplified scale. Assessment of subconjunctival haemorrhage and chemosis was made by the surgeon. The percentage of patients reporting any pain on administration of superior SCA was 46% compared to 67% with inferior SCA (P=0.036). Moderate to severe pain on SCA injection was experienced by 15% and 18% of those in the superior and inferior SCA groups respectively. The cataract procedure was well tolerated in both groups. There was no difference between the groups for duration of surgery (P =0.25), anaesthetic related complications including chemosis (P =0.28), subconjunctival haemorrhage (P=0.38) or intraoperative complications (P =0.50). We found that subconjunctival anaesthesia is effective for routine cataract surgery. There was no difference in block efficacy between superiorly and inferiorly delivered SCA. However, superior SCA appeared to be less painful on injection compared to inferiorly delivered SCA.