LAUSR

e796 www.ccmjournal.org September 2019 • Volume 47 • Number 9 According to the authors, Figure 1B and 1C in (1) has been taken in an axial approach and Figure 1E and 1F in (1) has been taken in a coronal approach. To be sure that the measurement is taken in an axial approach, the scanned plane should include the lens and the optic nerve insertion. In this way, it is possible not only to be sure to be on axis but also to have reference points to measure the ONSD at the same 3-mm distance from the ON insertion. Unfortunately, neither in Figure 1B, nor in Figure 1C in (1), is possible to see the lens and, more importantly, in Figure 1C in (1), the scan does not correspond to the ON insertion, in fact the ocular wall and some orbital tissue are visible between the sclera and the optic nerve. In our opinion, this makes the image look more like a transverse scan than an axial one, as it is more similar to Figure 1E and 1F than Figure 1B in (1). May be the image was incorrectly chosen. Furthermore the authors, in the figures note, state that the optic nerve is showed as a “sharply demarcated circle, measured at its widest diameter (E). If edema is seen the measurement is taken at the outer edge (F, outer calipers).” We have some concerns in regard to this statement. First of all, if an optic nerve edema is suspected by the examiner, the measurement was made including other structures, making obvious that this will appear larger. Additionally, it seems that, according to the authors, the low reflective circle should be the optic nerve and the surrounding higher reflective structure should prove the presence of edema. In our opinion, this statement should not correspond to the anatomic conditions. To the best of our knowledge, in case of intracranial hypertension, the ONSD increase is due to the increased presence of subarachnoidal fluid between the arachnoid and pia that surrounds the optic nerve. According to the authors, it seems that the optic nerve, which is a solid structure, appears less reflective than liquor, which is a fluid. How can it be? In our opinion, this description is difficult to explain. The authors have disclosed that they do not have any potential conflicts of interest.