Effects of Different MAP Targets on Ocular Perfusion and Optic Nerve Microvasculature During Rhinoplasty

This randomized controlled trial aims to evaluate the effects of two different mean arterial pressure (MAP) targets during controlled hypotension on ocular perfusion and optic nerve head microvasculature in patients undergoing elective rhinoplasty or septorhinoplasty. A total of 60 patients will be randomized in a 1:1 ratio to a target MAP of either 50-60 mmHg or 60-70 mmHg during general anesthesia. Intraocular pressure (IOP) will be measured at predefined perioperative time points, and estimated ocular perfusion pressure (OPP) will be calculated using simultaneous MAP and IOP measurements. Optical coherence tomography angiography (OCTA) will be performed preoperatively and postoperatively to assess changes in peripapillary, optic nerve head, and macular microvascular parameters. The primary objective is to compare changes in peripapillary vessel density between the two MAP target groups. Secondary objectives include evaluating changes in optic nerve head microvasculature, intraoperative OPP and IOP, and the relationships between the depth and duration of hypotension and OCTA-derived microvascular changes.

Inclusion Criteria: * Age 18-50 years * Scheduled for elective rhinoplasty or septorhinoplasty * American Society of Anesthesiologists (ASA) physical status I-II * Willing and able to provide written informed consent Exclusion Criteria: * History of glaucoma, retinal disease, optic neuropathy, or other significant ophthalmologic disease * Previous ocular surgery * High myopia * Uncontrolled hypertension, diabetes mellitus, or other serious systemic disease * ASA physical status III or higher * Development of severe intraoperative hemodynamic instability * Massive intraoperative bleeding * Inadequate OCTA image quality for analysis * Pregnancy * Refusal to participate or withdrawal of consent