Comparison of low-volume versus high-volume sub-Tenon’s anesthesia for phacoemulsification cataract surgery: a prospective randomized controlled study

Background Advances in cataract surgery including the use of phacoemulsification have shortenedthe duration of surgery, resulting in the use of shorter acting anesthetic agents with less invasive methods of administration. Thus, a small volume (1 ml) of short and rapidly acting local anesthetics (lidocaine) have been used in sub-Tenon’s block for anesthesia of such operations. Purpose The aim of the present study was to reduce the complications of sub-Tenon’s anesthesia by using low-volume lidocaine and to study its benefits with regard to pain during surgery and ocular akinesia.Methods Sixty patients of American Society of Anaesthesiologists (ASA) grade I–III, aged between 18 and 70 years, scheduled for phacoemulsification cataract surgery were randomly assigned to two groups. Group I received 1ml of 10% lidocaine and group II received 3–5 ml of a mixture of 2% lidocaine and 0.5% bupivacaine. Pain during administration of anesthesia and during surgery was graded using the verbal analogue scale and compared for both groups. Subconjunctival hemorrhage, chemosis, akinesia, and major complications such as brainstem anesthesia, optic neuropathy, globe perforation, hemorrhage, and squint were also compared. Results Pain during administration of anesthesia was significantly lower in group I compared with group II, and more patients in group I compared with group II were pain free, without a significant difference between the two groups. Akinesia, subconjunctival hemorrhage, and chemosis occurred less often and patient and surgeon satisfaction was significantly better in group I compared with group II. No major complications were detected in both groups. Conclusion Lidocaine (10%) at a dose of 1ml is safe and effective for sub-Tenon’s anesthesia and is a suitable alternative to the mixture of 2% lidocaine and 0.5% bupivacaine used traditionally.