This prospective observational study investigates whether routine pre-sedation isotonic fluid replacement and the passage of the endoscope into the duodenum acutely affect intraocular pressure (IOP) in adult patients undergoing diagnostic upper gastrointestinal endoscopy. A non-contact tonometer is used to measure IOP at four predefined time points: baseline, after pre-sedation fluid replacement, after sedoanalgesia, and immediately following duodenal intubation. Hemodynamic parameters, oxygen saturation, and sedative doses are also recorded. The primary aim is to determine changes in IOP during the procedure, while secondary outcomes include the relationship between hemodynamic fluctuations, sedative requirements, and IOP changes. The findings are expected to provide insights into the safety of endoscopy with respect to ocular physiology, particularly in patients at risk of increased intraocular pressure.

This single-center, prospective, observational cohort study is conducted at Elazig Fethi Sekin City Hospital, Türkiye. The study population consists of adults (≥18 years) scheduled for diagnostic upper gastrointestinal endoscopy under routine sedoanalgesia. Consecutive eligible patients are enrolled until the target sample size of 40 is reached. Exclusion criteria include any history of glaucoma, ocular surgery, or ongoing ophthalmological treatment.

All participants receive standard pre-sedation isotonic fluid replacement (500 mL) as per institutional protocol. Sedoanalgesia is administered with propofol, midazolam, and fentanyl at the discretion of the attending anesthesiologist, following routine practice. Intraocular pressure (IOP) is measured using a calibrated non-contact tonometer at four time points: (1) baseline before fluid loading, (2) after fluid replacement and before sedation, (3) after sedoanalgesia, and (4) immediately following duodenal intubation. Measurements are consistently taken from the same eye and patient position to ensure reliability.

In addition to IOP, systolic/diastolic blood pressure, mean arterial pressure, heart rate, and peripheral oxygen saturation are continuously monitored and recorded. Sedative drug doses and procedure times (total duration and time to duodenal passage) are documented. The primary outcome is the change in IOP between baseline and post-duodenal intubation. Secondary outcomes include correlations between hemodynamic variables, sedative consumption, and intraocular pressure changes, as well as subgroup analyses according to age, sex, and comorbidities.

Statistical analysis will include repeated-measures ANOVA or non-parametric equivalents to compare IOP at different time points, along with regression models to identify predictors of IOP changes. With a sample size of at least 34 patients (allowing for 40 to compensate for dropouts), the study has adequate power to detect clinically significant differences.

The results are expected to contribute to a better understanding of the physiological ocular effects of upper GI endoscopy and to inform clinical practice, especially in patients at risk of elevated intraocular pressure.

Inclusion Criteria:

• Adults ≥18 years
• Scheduled for diagnostic upper gastrointestinal endoscopy under sedoanalgesia
• ASA physical status I-III
• Voluntarily provides informed consent

Exclusion Criteria:

• History of glaucoma or ocular hypertension
• Previous ocular surgery or ongoing ophthalmological treatment
• Known contraindications to sedoanalgesia (propofol, midazolam, fentanyl)
• ASA physical status IV or higher

Adult patients (≥18 years) scheduled for diagnostic upper gastrointestinal endoscopy under sedoanalgesia at Elazig Fethi Sekin City Hospital. Consecutive eligible patients will be approached and enrolled after providing informed consent.

Individual participant data will not be shared because the study is a single-center observational project with a limited sample size and no data repository plan. Only aggregated results will be reported in publications.