Ahmad, Rubia, et al. “Noninvasive Ultrasound Assessment of the Normal Optic Nerve Sheath Diameter in Healthy Adults: An Islamabad-Based Pakistani Population Study”. Journal of Ophthalmology and Research, vol. 3, no. 4, Nov. 2020, pp. 86-95, https://fortunejournals.org/ojs/index.php/jor/article/view/17393.