This study aims to evaluate the effects of pre-intubation oropharyngeal topical lidocaine on optic nerve sheath diameter (ONSD) post-endotracheal intubation. The study will measure the ONSD using ultrasonography before intubation, and at 1, 5, and 10 minutes post-intubation. The results will be compared between patients receiving %10 lidocaine topically and %2 intravenous lidocaine.

Increased intracranial pressure (ICP) is a critical condition that requires early and accurate assessment. Traditional invasive ICP monitoring techniques, such as lumbar puncture and intracranial pressure monitoring devices, carry significant risks. Optic nerve sheath diameter (ONSD) measurement via ultrasonography is a non-invasive method that reflects increased ICP.

Patients will be divided into two groups: Group A will receive %10 topical oropharyngeal lidocaine, and Group B will receive %2 intravenous lidocaine. The primary aim of the study is to evaluate the impact of lidocaine on ONSD at 1, 5, and 10 minutes post-intubation and to compare the effects on the two groups.

Inclusion Criteria:

• ASA class I or II
• Age 18-65 years
• BMI 18-30
• No history or expected difficult intubation
• No glaucoma or ocular pathology
• No intracranial pressure increase

Exclusion Criteria:

• ASA class III and above
• Obesity (BMI > 30)
• Difficult intubation history or risk
• Glaucoma or other ophthalmic pathology
• History of intracranial pressure increase or prior ophthalmic/intracranial surgery
• Preoperative sedation
• Active malignancy or ongoing radiotherapy/chemotherapy

The individual participant data (IPD) will be made available upon request to scientific committees or researchers for further analysis, subject to ethical and privacy considerations.

Double-blinded (Participants and Outcome Assessors)