Impaired cerebrospinal fluid dynamics along the entire optic nerve in normal-tension glaucoma.

Abstract

To investigate the cerebrospinal fluid (CSF) dynamics along the entire optic nerve (ON) in patients with normal-tension glaucoma (NTG). Retrospective analysis of computed tomographic (CT) cisternographies in Caucasian patients with NTG. Fifty-six patients (99 of 112 eyes) fulfilled the diagnostic criteria of NTG and underwent CT-cisternography. Twelve subjects without NTG (24 eyes) served as controls. Contrast-loaded cerebrospinal fluid (CLCSF) density measurements in Hounsfield units (HU) were performed at four defined regions along the ON and in the basal cistern. In NTG patients, the mean density CLCSF in the bulbar segment measured 76±49HU right and 88±74HU left, in the mid-orbital segment 117±92HU right and 119±73HU left, in the intracanalicular ON portion 209±88HU right and 216±101HU left, in the intracranial ON portion 290±106HU right and 286±118HU left and in the basal cistern 517±213HU. The distribution of CLCSF along the ON showed a statistically significant reduction in the intraorbital ON segments in NTG patients compared to controls without NTG with the far largest difference within the retrobulbar segment (-150HU right and -117HU left; right: p<0.001, left: p<0.001). This study demonstrates a gradual reduction in CLCSF towards the retrobulbar segment in NTG, while in controls without NTG, no reduction in CLCSF was measured within the orbital segments. Impaired CSF dynamics along the ON may contribute to the pathophysiology of NTG.