COLOR DOPPLER ULTRASOUND MEASUREMENTS AFTER TOPICAL AND RETROBULBAR EPINEPHRINE IN PRIMATE EYES

Purpose. To determine the effects of topical epinephrine and retrobulb ar anesthesia containing lidocaine with epinephrine on retrobulbar hem odynamic measurements in the primate eye, using color Doppler ultrasou nd. Methods. Color Doppler ultrasound measurements were performed al b aseline and 90 minutes after masked administration of topical 2% epine phrine or balanced salt solution to six cynomolgus monkeys. Measuremen ts were also performed at baseline and 30 minutes after retrobulbar in jection of 2% lidocaine, with or without 1:200,000 epinephrine. Result s. After topical epinephrine, color Doppler ultrasound measurements we re not signifi cantly different compared with baseline measurements in the central retinal artery, posterior ciliary arteries, and superior ophthalmic vein. There were decreased systolic and diastolic velocltie s 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 contra st, there were marked changes in the retrobulbar arterial circulation after retrobulbar injection of lidocaine with epinephrine. The systoli c and diastolic velocities were decreased significantly in the central retinal artery (P < 0.02 and P < 0.01, respectively), temporal poster ior ciliary artery (P < 0.05 and P < 0.03, respectively), and nasal po sterior ciliary artery (P < 0.03 and P < 0.02, respectively). Pourcelo t's ratio was significantly increased in the central retinal artery (P < 0.01), temporal posterior ciliary artery (P < 0.02), and nasal post erior ciliary artery (P < 0.02) after retrobulbar injection of lidocai ne with epinephrine. Conclusions. These results indicate that one drop of topical epinephrine has little or no effect on the retrobulbar-cir culation, whereas retrobulbar injection of anesthetic solution contain ing lidocaine with epinephrine significantly alters retrobulbar hemody namics in the monkey eye.