Objectives: The objective of this research was to assess the impact of rapid maxillary expansion on intracranial pressure in individuals with maxillary transverse deficiency. This was achieved by measuring the optic nerve sheath diameter using ultrasonography (US). Materials and Methods: This prospective observational study included 25 young patients (mean age 13.10 ± 1.20) with bilateral posterior cross bite. Acrylic cap splint hyrax appliances were given to all patients for rapid maxillary expansion (RME). Prior to the initial screw activation (T0), the patient underwent monitoring, collection of vital signs, and measurement of optic nerve sheath diameter (ONSD) using US. Subsequent measurements were taken at 1 minute (T1), 10 minutes (T2), and 60 minutes (T3) following the first activation. During the final session of the rapid maxillary expansion therapy, the same measurement procedure was repeated (T4, T5, T6, and T7) as in the initial activation session. The patients' perception of pain during screw activation (T1, T5) was also assessed using a four- category verbal rating scale (VRS-4). A p-value of less than 0.05 was considered statistically significant for the conducted analysis. Results: The ONSD values, at T1 and T5, showed a significant increase within 1 minute following screw activation. However, there was no significant difference observed between the initial (T0) and final (T7) ONSD values throughout the active RME therapy. Conclusions: Intracranial pressure rises immediately after screw activation, but it auto regulates at the end of the active RME therapy.