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Abstract
PURPOSE: To determine the effects of topical epinephrine and retrobulbar anesthesia containing lidocaine with epinephrine on retrobulbar hemodynamic measurements in the primate eye, using color Doppler ultrasound. METHODS: Color Doppler ultrasound measurements were performed at baseline and 90 minutes after masked administration of topical 2% epinephrine or balanced salt solution to six cynomolgus monkeys. Measurements were also performed at baseline and 30 minutes after retrobulbar injection of 2% lidocaine, with or without 1:200,000 epinephrine. RESULTS: After topical epinephrine, color Doppler ultrasound measurements were not significantly different compared with baseline measurements in the central retinal artery, posterior ciliary arteries, and superior ophthalmic vein. There were decreased systolic and diastolic velocities in the ophthalmic artery (P < 0.03 and P < 0.02, respectively) after topical epinephrine; however, Pourcelot's ratio (resistive index) was not significantly different compared with that at baseline. In contrast, there were marked changes in the retrobulbar arterial circulation after retrobulbar injection of lidocaine with epinephrine. The systolic and diastolic velocities were decreased significantly in the central retinal artery (P < 0.02 and P < 0.01, respectively), temporal posterior ciliary artery (P < 0.05 and P < 0.03, respectively), and nasal posterior ciliary artery (P < 0.03 and P < 0.02, respectively). Pourcelot's ratio was significantly increased in the central retinal artery (P < 0.01), temporal posterior ciliary artery (P < 0.02), and nasal posterior ciliary artery (P < 0.02) after retrobulbar injection of lidocaine with epinephrine. CONCLUSIONS: These results indicate that one drop of topical epinephrine has little or no effect on the retrobulbar circulation, whereas retrobulbar injection of anesthetic solution containing lidocaine with epinephrine significantly alters retrobulbar hemodynamics in the monkey eye.