Incidence and factors associated with complications after retrobulbar anesthesia in Thailand: results from King Chulalongkorn Memorial Hospital

Background: Retrobulbar anesthesia is a routine regional block for various ocular surgeries, but serious complications may occur. There have been no previous incidence reports and associating factors with these complications in Thailand. Objective: To study the incidence and factors associated with complications after retrobulbar anesthesia in Thailand. Methods: Samples were all consecutive cases undergoing retrobulbar anesthesia at King Chulalongkorn Memorial Hospital between June 2006 and May 2007. All subjects have given informed consent to participate in the study. The variables recorded included the subject baseline data, the retrobulbar block technique, and complications. Descriptive statistics and multiple logistic regression were used to analyze the data. Results: One thousand eighty eyes from 1072 patients were studied. Underlying systemic diseases were present in 48.1% of cases. Underlying ophthalmic diseases included glaucoma 3.5% and retinal diseases 3.5%. Thirty-four percent of the eyes underwent phacoemulsification and 24.1% underwent extracapsular cataract extraction. Pars plana vitrectomy was performed in 25.9% of the eyes. Other procedures included corneal surgery, strabismus correction, endoscopic cyclophotocoagulation, and evisceration. The majority of the retrobulbar block was performed by the first year residents (67.3%). All of the blocks were performed by dominant hands. Complications after retrobulbar block were seen in 4.7% (95% CI=3.5-6.0%) of the eyes. Lid swelling, chemosis, and ecchymosis were seen in 23 eyes (2.1%). Retrobulbar hemorrhage was detected in 24 eyes (2.2%). Optic nerve injection and subarachnoid injection were seen in four eyes (0.4%). Factors associated with severe complications were patient age of 60 years or more, and history of recent use of anticoagulants. Conclusion: The incidence of complications after retrobulbar block is 4.7% of the eyes. Severe complications occur more frequently in elderly patients and recent use of anticoagulants.