This study investigates the effects of epidural anesthesia on intracranial pressure (ICP) by using ultrasonographic optic nerve sheath diameter (ONSD) measurements as a non-invasive indicator. The study aims to determine if the volume of local anesthetic applied to the epidural space during total knee replacement surgery leads to transient increases in ONSD compared to spinal anesthesia. Participants are randomized into two groups to receive either epidural or spinal anesthesia, and their ONSD measurements are tracked before, during, and after the surgery.