Optic Nerve Changes Detected with Ocular Ultrasonography during Different Surgical Procedures: A Narrative Review

Abstract

Ultrasonographic appraisal of the optic nerve sheath diameter has become popular in recent years as a useful diagnostic tool to detect intracranial pressure variations. Intracranial hypertension is a life-threatening disease with possible poor clinical outcomes and can be caused by a variety of neurological and non-neurological conditions. Considering the latter, increases in intracranial pressure have also been described during several surgical procedures. Ocular ultrasonography might be utilized to identify intracranial pressure increases by evaluating optic nerve sheath diameter variations. The aim of this review is to provide a wide overview on the use of the optic nerve ultrasound evaluation to detect intracranial pressure changes during surgical procedures, also discussing the pitfalls of the B-scan technique, the most widely used for such a purpose. PubMed medical database, Web of Science and Scopus were used to carry out this review. The present review showed that ocular ultrasonography could be considered a valuable diagnostic tool in the surgical setting to indirectly assess intracranial pressure. However, the use of the B-scan ultrasound should always be coupled with the standardized A-scan technique for a more accurate, precise and trustworthy ultrasound assessment.

A review of invasive intracranial pressure monitoring following surgery for hypertensive cerebral hemorrhage

“…An increase in intracranial pressure can cause the optic nerve sheath diameter in the retrobulbar chamber to expand, and ultrasound can be used as a non-invasive tool for assessing intracranial pressure by measuring the optic nerve sheath diameter ( 38 ). However, ocular ultrasound lacks a clear- cut-off value as an indicator of elevated intracranial pressure when using the optic nerve sheath diameter as an indirect assessment ( 39 ), and it is a difficult test that requires a high level of knowledge and a trained operator, which is one of its drawbacks ( 40 , 41 ).…”

Comment on: Diagnostic Accuracy of Optic Nerve Sheath Diameter Measured With Ocular Ultrasonography in Acute Attack of Chronic Obstructive Pulmonary Disease

“…Even if this method has been used by several authors in the international literature, placing the probe over closed eyelids makes very difficult to assess the gaze direction, resulting in a wrong probe orientation and a wrong ONSD measurement. 2,3 Besides, the obtained signal strength is reduced by the glove. For these reasons, we suggest performing ocular echography with open eyelids, using methylcellulose and anesthetic drops, to visualize the patient's gaze to correctly orient the probe and without any cover that may interfere with the ultrasound.Another point that we would like to discuss is the use of a B scan probe.…”