General anesthesia significantly decreases arterial retrobulbar blood flow velocity in glaucoma patients

Purpose To investigate the influence of general anesthesia (GA)-induced systemic hypotension on retrobulbar blood flow and pressure flow-coupling in glaucomatous versus non-glaucomatous eyes. Methods Prospective single-center case-control study including glaucoma and non-glaucomatous patients scheduled for ocular surgery under GA. Retrobulbar blood flow velocities were assessed with color Doppler imaging before and 1-min after GA induction simultaneous with blood pressure (BP) measurements. Linear mixed-effects models with random intercepts for subjects were used to evaluate the effects of group, time, and their interaction on MFV, adjusting for age, gender, intraocular pressure, statin, and systemic antihypertensive medication. A three-way interaction model analyzed pressure–flow coupling. Results Twenty-seven glaucoma patients and 37 controls were included. GA induction caused comparable reductions in systolic BP in both groups ( p < 0.001). A significant group × time interaction was observed for MFV (β=−5.46 cm/s; p = 0.004). MFV remained stable in controls but decreased significantly in glaucoma patients. A significant group × time × MAP interaction ( p = 0.009) revealed altered pressure–flow coupling in glaucoma patients. No differences were observed between primary and secondary glaucoma. Conclusion Glaucomatous eyes demonstrated impaired autoregulatory responses to GA-induced hypotension, suggesting increased vulnerability to perfusion stress during general anesthesia. Clinical trial registration: ClinicalTrials.gov identifier: NCT01840215