comparison between two local anaesthetic methods: parabulbar anesthesia using ptfe intravenous cannula (no needle) and retrobulbar anesthesia in extracapsular cataract surgery

purpose: to compare the efficacy and safety of two local anesthetic methods; retrobulbar anesthesia and parabulbar anesthesia using ptfe intravenous cannula without needle in extracapsular cataract surgery. method: a randomized prospective partially blind study was conducted on 66 eyes of 66 patients with senile cataract who were scheduled for ecce and pc iol surgery. after randomization, 35 patients received retrobulbar anesthesia and 31 received parabulbar anesthesia. iop was measured preoperatively and 1, 5, 15, and 30 min after injection. akinesia was measured 1, 5, 15, and 30 min after injection. akinesia was graded as 0, 1, 2, in which zero means complete absence of movement or minimal movement around primary position; 1 means relative akinesia: residual movement of one muscle or relative reduction of muscle movement in all directions; and 2 means no akinesia. pain was measured using a 10 point visual analog scale immediately after injection. parabulbar anesthesia was performed with an iv cannula, gauge 22, 25 mm length, made from ptfe (poly tetra fluoro ethylene). the iv cannula sheath was used and its needle was discarded. results: patients included 47% female and 53% male subjects. mean age was 68 yr. there was no significant difference in the age and sex distribution and preinjection intraocular pressure between two groups. akinesia was significantly more complete at all times after injection in group with parabulbar anesthesia. iop was significantly higher at all times after injection in eyes with parabulbar anesthesia. pain sensation was not significantly different between two groups. major complications were not seen in any groups. minor complications including chemosis (32%) and hemorrhage at site of peritomy (95%) were seen in parabulbar group. conclusion: parabulbar anesthesia produces better and faster akinesia than retrobulbar anesthesia but it can cause more iop elevation that should be considered in patients with compromised ocular circulation. this needle-free variation of parabulbar anesthesia in an effective and safe technique for local anesthesia in cataract surgery.