THE ULTRASONIC LOCALIZATION OF RETROBULBAR NEEDLES DURING RETROBULBARBLOCK

Purpose: The tips of retrobulbar needles were visualized during retrob ulbar block using ultrasound. The purpose of this study is to see how often the needle tip was located 5 mm behind the hind surface of the g lobe. Methods: Twenty-five patients ranging in age from 22 to 84 years were studied after written informed consent was obtained. An ultrason ic photograph was taken before needle placement, with the needle in th e proper position, and after local anesthetic had been injected. Resul ts: In none of the 25 patients studied was the needle tip at the 5-mm mark behind the eye. Placement ranged from 0.2 to 3.3 mm behind the gl obe. In 14 to 25 placements, the needle shaft was seen actually to ind ent the globe. The optic nerve was seen to be at least 9 mm from the n eedle tip in 6 of 25 patients. Conclusion: This study demonstrates tha t retrobulbar needle tips are closer to the globe than thought previou sly. A false sense of security may occur when performing retrobulbar b locks using only anatomic landmarks.