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

Abstract

PurposeGlaucoma 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.MethodsProspective, 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.Results53 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).ConclusionsThese 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).