AUTHOR=Pircher Achmed , Montali Margherita , Berberat Jatta , Remonda Luca , Killer Hanspeter E. 

TITLE=The Optic Canal: A Bottleneck for Cerebrospinal Fluid Dynamics in Normal-Tension Glaucoma?

JOURNAL=Frontiers in Neurology

VOLUME=Volume 8 - 2017

YEAR=2017

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2017.00047

DOI=10.3389/fneur.2017.00047

ISSN=1664-2295

ABSTRACT=Purpose
To report on the optic canal cross sectional area (OCA) in Caucasian patients with normal-tension glaucoma (NTG) compared with Caucasian control subjects without known optic nerve (ON) diseases.

Methods:
Retrospective analysis of computed tomographic (CT) images of the cranium and orbits in 56 NTG patients (30 females and 26 males; 99 of 112 eyes; mean age 67.7±11.1 years). 56 age- and gender matched subjects (mean age: 68.0±11.2 years) without known ON diseases served as controls. The OCA at the orbital opening was measured in mm² by using the tool “freehand”. Statistical analysis was performed by using the independent two-tailed t-test.

Results:
The mean orbital opening OCA in NTGs measured 14.5±3.5 mm², (right OCA: 14.4±3.6 mm2, left OCA: 14.5±3.4 mm²) and in controls 18.3±2.6 mm² (right OCA: 18.5±2.7 mm², left OCA: 18.1±2.5 mm2). The difference between NTG and controls was statistically significant (p<0.000 for the right OCA, p<0.000 for the left OCA).

Conclusions:
This study demonstrates narrower OCAs in Caucasian NTG patients compared to Caucasian control subjects without known optic nerve (ON) diseases. Narrower OCAs might contribute to a discontinuity of the cerebrospinal fluid (CSF) flow between the intracranial and orbital subarachnoid space (SAS) in NTG patients. This might have an influence onto the pathophysiology in NTG.