Ultrasound measurement of Optic Nerve Sheath Diameter in a Colombian healthy adult population

Abstract

Background Measurement of optic nerve sheath diameter (ONSD) provides a rapid, safe, and easy method for detecting increased intracranial pressure (ICP). However, normal mean and upper limit values may vary according to age, sex, ethnicity, and ultrasound laboratory. Aim We aim to obtain the mean of ONSD in a healthy Colombian adult population and correlate it with demographic and anthropometric measures. Methods In a prospective study using a 10-13MHz linear ultrasound probe, transverse bulb diameter (TBD) and ONSD in transverse (ONSD-TP) and sagittal plane (ONSD-SP) were measured in healthy adults volunteers in Bogota, Colombia. Results A 100 healthy subjects were included, mean age 26,7 ± 8,3 years with 62 women. For 95% of the subjects the mean TBD, ONSD-TP and ONSD-SP was 23.11mm (CI: 22.90mm-23.32mm), 3.96mm (CI: 3.85mm-4.07mm) and 4.0mm (CI: 3.90mm-4.11mm) respectively. ONSD in both planes ranged from 2.35mm to 5.20mm. There was a correlation between ONSD-SP and ONSD-TP (p < 0.0001) but no correlation between ocular measures and demographic or anthropometric variables (p > 0.05). Intraclass correlation between eyes was statistically significant. Conclusion Our study shows that ultrasound measured ONSD in healthy adults in Colombia is similar to those found worldwide. An ONSD of 5.5mm may be considered the upper limit for healthy adults in Colombia. ONSD could be measured in either plane, there is a good correlation between the two eyes and ONSD is not modified by demographic or anthropometric characteristics.