This prospective study aims to evaluate the effect of steep Trendelenburg position and pneumoperitoneum on optic nerve sheath diameter in patients undergoing robot-assisted laparoscopic radical prostatectomy and open radical prostatectomy under general anesthesia. Increased intracranial pressure may occur during robotic surgery due to pneumoperitoneum and head-down positioning. Optic nerve sheath diameter measured by ocular ultrasonography is a non-invasive method used to assess intracranial pressure changes. Hemodynamic and respiratory parameters will also be recorded during surgery. The results of this study may help to better understand the physiological effects of surgical position and pneumoperitoneum during prostatectomy procedures.

Robot-assisted laparoscopic radical prostatectomy requires steep Trendelenburg positioning and carbon dioxide pneumoperitoneum to improve the surgical field. These conditions may lead to increased intracranial pressure due to venous congestion and elevated intrathoracic pressure. Optic nerve sheath diameter measurement by ultrasonography is a noninvasive method that can be used to estimate changes in intracranial pressure during surgery.

In this prospective study, patients undergoing robot-assisted laparoscopic radical prostatectomy will be compared with patients undergoing open radical prostatectomy. Optic nerve sheath diameter will be measured at predefined time points during surgery using ocular ultrasonography. Hemodynamic parameters, respiratory variables, intra-abdominal pressure, duration of surgery, blood loss, and administered fluids will also be recorded.

The aim of this study is to evaluate the effect of pneumoperitoneum and steep Trendelenburg position on optic nerve sheath diameter and to determine the relationship between optic nerve sheath diameter and intraoperative physiological changes.

Inclusion Criteria:

• Age ≥ 18 years
• ASA physical status I-III
• Patients scheduled for robot-assisted laparoscopic radical prostatectomy or open radical prostatectomy under general anesthesia
• Written informed consent obtained

Exclusion Criteria:

• History of intracranial surgery or intracranial lesion
• Known ocular disease (glaucoma, retinal detachment, diabetic retinopathy, previous ocular surgery, etc.)
• Intraocular pressure greater than 30 mmHg
• Refusal to participate in the study

Adult male patients aged 18 years and older with ASA physical status I-III who are scheduled for robot-assisted laparoscopic radical prostatectomy or open radical prostatectomy under general anesthesia at Ege University Faculty of Medicine Hospital will be included in this prospective observational study.

Individual participant data will not be shared due to privacy and institutional restrictions.