Measurement and Associations of the Optic Nerve Subarachnoid Space in Normal Tension Glaucoma and Primary Open-Angle Glaucoma REPLY

Liu and associates reported the results of their study measuring the area of the optic nerve subarachnoid space in patients with normal tension glaucoma (NTG), patients with primary open-angle glaucoma (POAG), and controls. 1 Liu H. Yang D. Ma T. et al. Measurement and associations of the optic nerve subarachnoid space in normal tension glaucoma and primary open-angle glaucoma. Am J Ophthalmol. 2018; 186: 128-137 Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar Measurements were obtained from 3 to 7 mm posterior to the globe to obtain the “area of the optic nerve subarachnoid space.” There was significantly reduced optic nerve subarachnoid space area in patients with NTG compared to normal controls. The authors conclude that this is an indication of reduced intracranial pressure that has been associated with normal tension glaucoma in both retrospective and prospective studies. Further, these results are consistent with Wang and associates' prior work, 2 Wang N. Xie X. Yang D. et al. Orbital cerebrospinal fluid space in glaucoma: the Beijing intracranial and intraocular pressure (iCOP) study. Ophthalmology. 2012; 119: 2065-2073 Abstract Full Text Full Text PDF PubMed Scopus (112) Google Scholar which revealed smaller optic nerve sheath widths in patients with NTG compared to normal controls. These conclusions are justified based on many studies, some mentioned by the authors, that indicate a relationship between optic nerve sheath width size and intracranial pressure. Measurement and Associations of the Optic Nerve Subarachnoid Space in Normal Tension and Primary Open-Angle GlaucomaAmerican Journal of OphthalmologyVol. 186PreviewTo measure the area of the optic nerve subarachnoid space (ONSASA) in patients with normal tension glaucoma (NTG), primary open-angle glaucoma (POAG), and controls and examine its association with relevant ocular and systemic parameters. Full-Text PDF ReplyAmerican Journal of OphthalmologyVol. 190PreviewWe thank Drs Fleischman and Killer for their insightful and interesting comments on our study. Full-Text PDF