To evaluate the influence of demographic factors on optic nerve sheath diameter (ONSD) in a Mexican population.

In this cross-sectional study using a 13-6 MHz linear ultrasound probe we assessed the relationship between demographic factors and ONSD in the transverse (ONSD-TP), sagittal planes (ONSD-SP),and the transverse diameter of the eye (ETD), measured in both eyes across two times. Linear mixed-effects models were used to analyze the impact of demographic variables on these measurements, accounting for within-subject correlation with random intercepts. 

A total of 40 healthy subjects were included with a mean age of 39.1 +/- 18.67 of which 19 were females. The mean ETD, ONSD-TP, and ONSD-SP was 22 +/- 1.6 mm, 5.3 +/- 0.5 mm, and 5.2 +/- 0.5 mm, respectively.  Age emerged as a significant predictor of ONSD across multiple models, with significant effects observed in the measurement of ONSD in the longitudinal plane (p=0.008). In contrast, weight, height, and BMI were not significant predictors. The marginal R-squared values ranged from 4.7% to 17.9%, indicating that the fixed effects explain a limited proportion of variance, while conditional R-squared values ranged from 36% to 44.8%, showing a substantial contribution from individual differences. 

Age significantly influences ONSD, particularly in the longitudinal and sagittal planes. These findings highlight the need for future studies in Latin American populations, with adjustments for age, to establish more accurate reference values for ONSD.