Correlation of Retinal Vessel Analysis and Nerve Fiber Layer Thickness in Normal Tension Glaucoma

Background: To investigate the retinal vessel diameter and its possible relationship with the retinal nerve fiber layer (RNFL) thickness in normal tension glaucoma (NTG). Methods: 86 NTG patients with detailed eye examination including retinal vessel analysis (DVA) and measurement of the RNFL thickness with scanning laser polarimetry (SLP; GDxVCC) were included in this retrospective study. The temporal retinal arteriolar diameters, temporal retinal venular diameters, vascular flicker response were compared with RNFL thickness and NFI (nerve fiber index). Results: The flicker response of DVA was significantly reduced as compared to normal eyes. The diameters of the temporal retinal arteriolar vessels were significantly correlated with RNFL thickness (P=0.0204) and NFI of GDxVCC (P=0.0021). The diameters of the temporal retinal venular were significantly correlated with the NFI (P=0.0298). Conclusion: Our results show that narrower arteriolar vessels are found in advanced NTG patients. These findings may be due to the decreased demand for retinal blood flow in damaged retina, but also may be one reason for the damage. Vessel analysis can contribute to the available tools predicting glaucomatous damage before visual field loss becomes manifest.