Related Experiment Video
Updated: Jan 21, 2026

Optic Nerve Sheath Point of Care Ultrasound: Image Acquisition
Published on: August 18, 2023
Ultrasound-measured optic nerve sheath diameter correlates well with cerebrospinal fluid pressure
Salil Gupta1, Aditya Pachisia2
1Department of Neurology, Army Hospital (Research and Referral), New Delhi, India.
Background:
Intracranial pressure (ICP) can be raised in many neurological conditions and must be treated early to prevent poor clinical outcomes. To detect the rising ICP, it is important to measure it repeatedly using a tool that is noninvasive, safe, accurate, and portable with minimal inter- and intraobserver variability. The aim of our study was to correlate cerebrospinal fluid (CSF) pressure with ultrasound (US)-measured optic nerve sheath diameter (ONSD) and find out a measurement which correlates best with CSF pressure of >20 cm of water.
Materials And Methods:
All patients in whom lumbar puncture (LP) was indicated and CSF pressure could be measured using manometer were included in the study. Ocular US was used to measure the ONSD.
Results:
A hundred patients were included in the study out of which 81% were males. The mean age was 60.5 years (±15.6) with a range of 26-90 years. Significant positive correlation was found between the ONSD and CSF pressure. Correlation coefficient (r) was 0.715 (P < 0.001). Receiver's operating characteristic curve was used to find out the ONSD value correlating with a CSF pressure of >20 cm of water. An ONSD >0.63 cm had a sensitivity of 77.3% [95% confidence interval (CI) 54.6-92.1] and specificity of 92.3% (95% CI 84.0-97.1) in predicting a CSF pressure of >20 cm of water (likelihood ratio [LR] + 10.05, LR - 0.25).
Conclusion:
There is a positive correlation of US-measured ONSD and LP-measured CSF pressure. ONSD of >0.63 cm suggests a CSF pressure of >20 cm of water.
Related Concept Videos
Cerebrospinal Fluid
CSF Production
CSF is produced mainly in the choroid plexus, a network of capillaries and ependymal cells located within the ventricular system of the brain....
Measurement of Fluid Pressure
A basic form of manometer is the piezometer, a vertical tube open at the top and filled with the same...
Pressure of Fluids
Fluid Pressure
According to Pascal's law, a fluid at rest will generate equal pressure in all directions. This pressure is measured as a force per unit area, and its magnitude depends on the fluid's specific...
Vapor Pressure of Fluid
When a liquid is placed in a closed container with a small air space, and the space is evacuated, vapor molecules will...
Pressure Variation in a Fluid at Rest
When measuring pressure at two different levels within the fluid, the difference in...

