Retrobulbar versus circumferential subconjunctival anesthesia on the pain control during planned extracapsular cataract extraction with intraocular lens implantation: a randomized equivalence trial

Abstract

Purpose: To compare the effectiveness on the pain control during extracapsular cataract extraction (ECCE) between retrobulbar anesthesia and circumferential subconjunctival anesthesia. Methods: Samples were from consecutive cataract cases undergoing ECCE with intraocular lens implantation at the 6th station of the relief unit, the Thai Red Cross Society from May to December 2003. Patients were randomized into two groups by simple randomization. Allocation sequence was concealed in separate sealed opaque paper packets. Group A received retrobulbar anesthesia, and Group B for circumferential subconjunctival anesthesia. The patients, the surgeon, and nurses were masked. Pain scales were recorded at the time of injection and during surgery using visual analogue score (VAS) from 0-100 mm. An equivalence limit of -10 to 10 was defined. Surgeon satisfaction scales using VAS, complication rate, operation time, rescue medication use were recorded. Results: A total of 145 cases were studied. There were 81 patients in group A and 64 in group B. Three cases did not complete the study due to procedural change. One patient did not undergo the operation due to preoperative seizure. As-treated analysis showed that the 95% Cl of median difference of pain score during operation, and pain score at time of injection were -9 to 5 and -1 t 3, respectively. The 95% Cl of mean difference of the surgeon satisfaction score was 8.4 to 14.4, favoring group A. With the intention-to-treat analysis assuming worst-case and best-case scenarios, the results were similar. Unexpected and severe complications of the anesthetic injection and the operative complications were rare. Rescue medications were used more frequently in group A than group B (18% VS 3%, p = 0.007, Fisher's exact test) Conclusion: The pain score during operation is equivalent in both groups. The pain at time of injection between both groups are not different. The surgeon prefer retrobulbar anesthesia, but a higher rate of rescue medications are used in retrobulbar group. Severe complications are uncommon.