Intracranial pressure and translaminar pressure difference in normal-tension glaucoma patients with different glaucomatous visual field defects

Abstract

Background The aim of the study was to assess differences in intracranial pressure (ICP) and translaminar pressure difference (TPD) in normal-tension glaucoma (NTG) patients with different glaucomatous visual field mean defects (MD).Methods 58 NTG patients (17.2% male, 82.8% female) age 53.6(8.4) years were included in the prospective study. During the study intraocular pressure (IOP), non-invasive ICP, perimetry and confocal laser scanning tomography for optic nerve disc (OND) structural changes were assessed. Non-invasive ICP was measured using two-depth Transcranial Doppler device (Vittamed UAB, Kaunas, Lithuania. TPD was calculated as difference between IOP and ICP. NTG patients were divided into 3 sub-groups for comparison: 1) NTG patients with MD<-3 dB; 2) NTG patients with -3≥MD<-6 dB; 3) NTG patients with MD≥-6 dB. The level of significance p<0.05 was considered significant. Results NTG patients with MD<-3 dB had statistically significantly higher ICP (9.3(2.7) mmHg) compared to NTG patients with -3≥MD<-6 dB (7.2(2.3) mmHg) and NTG patients with MD≥-6 dB (7.3(1.7) mmHg), p=0.01. NTG patients with MD-6 dB had significantly lower retinal nerve fiber layer thickness (RNFLT) 0.17(0.1) mm, compared to NTG patients with MD<-3 dB (0.23(0.1) mm, p=0.002. There were no statistically significant differences in RNFLT between NTG patients with -3≥MD0.05 Conclusion NTG patients with initial visual field defects had higher ICP and lower TPD compared to NTG patients with more pronounced visual field defects. Our findings suggest that there is a need for further longitudinal prospective studies investigating the role of ICP in NTG using non-invasive ICP measuring technology to more specifically elucidate the mechanisms by which ICP and TPD may influence NTG pathophysiology.