Optic Nerve Sheath Diameter (ONSD) on ultrasound has been used to identify patients with high intracranial pressure. ONSD threshold measurements for high ICP range from 5 to 6mm. Unfortunately there´s not really been any reference values. A study in Journal of Critical Care measures on ONSD in healthy volunteers,reporting a mean ONSD of 3.68 mm. (95% confidence interval [CI], 2.85-4.40). There wa s a significant difference between men and women at 3.78 mm and 3.60 mm, respectively.
Study lives here.