OPTIC NERVE SHEATH DIAMETER AND INTRACRANIAL PRESSURE: MOLECULAR PATHOPHYSIOLOGY AND MULTIDISCIPLINARY APPLICATIONS IN OPHTHALMOLOGY, RADIOLOGY, AND GENERAL SURGERY

Abstract

Raised intracranial pressure is a major cause of secondary neurological injury, yet invasive monitoring is not always feasible, creating demand for reliable noninvasive indicators. This review examines optic nerve sheath diameter as a surrogate marker of intracranial pressure, with emphasis on its molecular basis and multidisciplinary clinical applications. The objective is to integrate current evidence on pressure transmission through the perioptic subarachnoid space, sheath distensibility, cerebral edema, blood–brain barrier dysfunction, neuroinflammation, and altered cerebrospinal fluid dynamics. Key outcomes indicate that ultrasonography, computed tomography, and magnetic resonance imaging can detect optic nerve sheath enlargement associated with intracranial hypertension, although diagnostic thresholds vary across populations, techniques, and clinical settings. Ophthalmological applications include papilledema and idiopathic intracranial hypertension assessment, whereas radiological and surgical applications extend to traumatic brain injury, perioperative monitoring, pneumoperitoneum, Trendelenburg positioning, and critical care surveillance. These findings imply that optic nerve sheath diameter is most useful when interpreted alongside neurological examination, fundoscopy, imaging signs, and physiological monitoring rather than as a standalone measurement. Standardized acquisition protocols, population-specific cutoffs, automated analysis, and multicenter validation are required. In conclusion, optic nerve sheath diameter offers a rapid, accessible, and repeatable approach to intracranial pressure assessment across diverse healthcare environments. The principal takeaway is that its greatest value lies in multidisciplinary, multimodal clinical decision making.