Purpose: Dilatation of the subarachnoid space of the optic nerve is shown to be an indicator of increased cerebrospinal fluid (CSF) pressure. The purpose of our study was to evaluate the effect of CSF pressure on the possible mechanism of low-tension glaucoma (NTG).
Materials & Methods: We examined 14 LTG patients' 28 eyes with T2 weighted magnetic resonance (MR) sequence and calculated the subaracnoid space area from the images obtained perpendicular to the optic nerve both 4 and 8 mm posterior to the optic disc. The calculation based on a subtraction of the optic nerve sheat area from the optic nerve area. We also evaluated 14 primary open angle glaucoma (POAG) patients' 28 eyes with the same procedure as the control group.
Results: The subarachnoid space areas 8 mm posterior to the optic disc are wider than the corresponding areas measured 4 mm posterior to the optic disc (p<0.001). However there is not a significant difference between the two glaucoma patient groups when calculated subaracnoid space areas are taken into consideration(p>0.1).
Conclusion: Althuogh we did not find significant difference between NTG and POAG patients by means of subarachnoid space width, this single study can not prove the indifference between the CSF pressurre and the NTG mechanism because it is thought to be a multifactorial process including the mechanical and vasoogenic factors. Thus further investigations should be performed to exclude possible effect of CSF pressure on this mechanism.