Ultrasound measurement of optic nerve sheath diameter in a healthy adult Colombian population

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