Translaminar pressure in Caucasian normal tension glaucoma patients

Purpose: The aim of this study was to examine the translaminar pressure difference (TLP) in Caucasian patients with normal tension glaucoma (NTG) and its possible impact onto the pathogenesis of NTG. Methods: Retrospective analysis of medical records of patients with open-angle glaucoma (OAG) in the period from 2005 to 2015 from the Ophthalmology Department, Cantonal Hospital Aarau, Switzerland. A total of 67 eyes of 38 patients (mean age 68 +/- 11.3years, 21 women and 17 men) fulfilled the diagnostic criteria of progressive NTG and underwent lumbar puncture (LP) during computer-assisted cisternography (CT - cisternography). The intraocular pressure (IOP) and lumbar cerebrospinal fluid pressure (CSF-p) were analysed and the TLP calculated. The TLP was compared with the mean defect (MD) of visual fields. Statistical analysis was performed with the one and two-tailed paired and unpaired t-test and the non-parametric Spearman correlation test. Results: The mean lumbar opening CSF-p measured 11.6 +/- 3.7mmHg. The mean IOP in the right eye measured 14.7 +/- 2.4mmHg, in the left eye 14.7 +/- 2.5mmHg. The calculated mean TLP was 3.0 +/- 4.2mmHg in the right and 3.3 +/- 4.3mmHg in the left eye. There was no significant correlation between TLP and the MD of visual fields in both eyes. Conclusions: This study did not confirm either a lower lumbar CSF-p or increased TLP compared to previous retrospective and prospective studies. As cerebrospinal fluid (CSF) flow is not homogenous throughout all CSF spaces and CSF-p and IOP fluctuate, the current view on TLP needs modifications to improve its validity.