Glaucoma patients have a significant decrease in retrobulbar blood flow velocities during general anesthesia.

Purpose Glaucoma patients are known to have an underlying vascular dysfunction and General anesthesia ( GA) significantly decreases blood pressure, which might decrease ocular perfusion. This study was conducted to investigate the effects of GA on ophthalmic flow velocities and blood pressure. Methods Prospective, case-control study. Glaucoma patients were scheduled for trabeculectomy or drainage device implantation; non-glaucomatous patients undergoing vitrectomy for macular hole or epiretinal membrane peeling were recruited as control subjects. Color Doppler imaging of the ophthalmic artery ( OA) was performed immediately before and 1 minute after GA induction. The following parameters were analyzed: OA blood velocities and resistivity index, as well as cardiovascular parameters (diastolic and systolic blood pressure and heart rate). Statistical analysis was performed using Student’s paired t test, Mann-Whitney, Fisher's exact test and Spearman's correlation. Results 53 patients were included (glaucoma group: 25; control group: 28). The magnitude in blood pressure decrease after GA induction was similar between the two groups (p value 0.61-0.70). However, the decrease in OA blood velocities was significantly larger in the glaucoma groups than in the control group (p < 0.03 in all comparisons). Unlike the control subjects, in the glaucoma group there was a significant association between the magnitude of blood pressure decrease and the lowering of the OA mean blood velocity ( r = 0.69, 95% IC: 0.36-0.87, p < 0.001). Conclusions These results suggest that glaucoma patients are unable to keep a stable blood velocity in the OA when subjected to acute significant decreases in blood pressure (such as the ones seen after GA induction). [ABSTRACT FROM AUTHOR]