The investigators aimed to analyze the ONSD diameters and its associated factors in Taiwanese healthy volunteers. We plan to recruit 150 healthy volunteers aged more than 20 years old. The ONSD and its associated factors will be measured and recorded by ultrasound from September 2020 to August 2021.

Ultrasound measurement of optic nerve sheath diameter (ONSD) had been considered as a non-invasive way to distinguish the presence of elevated intracranial pressure (ICP). Besides detecting elevated ICP in various neurological diseases, ONSD can also be applied to cardiac arrest survivors as one of the prognostic factors. It is a simple, quick, repeatable technique without the need of contrast medians. In order to make precise interpretations, the database of the normal distribution of ONSD and its associated factors in healthy volunteers is necessary. The majority of previous reports are from Western countries, and limited reports of ONSD in the Asian population have high variability.

Therefore, collecting local data of ONSD in Taiwan is important. In this study, the investigators aimed to analyze the ONSD diameters and its associated factors in Taiwanese healthy volunteers. The investigators planed to recruit 150 healthy volunteers aged more than 20 years old. The ONSD and its associated factors will be measured and recorded by ultrasound from September 2020 to August 2021.

Inclusion Criteria:

adult volunteer aged more than 20 years

Exclusion Criteria:

aged less than 20 years

normal volunteers