AUTHOR=Van Eijgen Jan , Heintz Alexander , van der Pluijm Claire , Delporte Margaux , De Witte Dries , Molenberghs Geert , Barbosa-Breda João , Stalmans Ingeborg 

TITLE=Normal tension glaucoma: A dynamic optical coherence tomography angiography study

JOURNAL=Frontiers in Medicine

VOLUME=Volume 9 - 2022

YEAR=2023

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.1037471

DOI=10.3389/fmed.2022.1037471

ISSN=2296-858X

ABSTRACT=Purpose 
Vascular dysregulation seems to play a role in the pathogenesis of glaucoma, in particular normal tension glaucoma (NTG). The development of optical coherence tomography angiography (OCT-A) enabled the measurement of the retinal microvasculature non-invasively and with high repeatability. Nonetheless, only a few studies transformed OCT-A into a dynamic examination employing a sympathomimetic stimulus. The goal of this study was to use this dynamic OCT-A exam (1) to differentiate healthy individuals from glaucoma patients and (2) to distinguish glaucoma subcategories, NTG and high-tension primary open angle glaucoma (POAG).
Methods 
Retinal vessel density (VD) in NTG patients (n=16), POAG patients (n=12) and healthy controls (n=14) was compared before and during a hand grip test with a hydraulic dynamometer.
Results 
At baseline, peripapillary VD was lower in POAG and NTG compared to healthy controls and higher in NTG compared to POAG when corrected for mean arterial pressure (MAP). Peripapillary and macular (superficial and deep) VD differences were found for gender, age and baseline MAP. No change in VD occurred (pre/post stimulus) in any of the groups. 
Conclusion 
Retinal VD loss in glaucoma patients was confirmed and the necessity to correct for gender, age and especially MAP was established. Although replication in a larger population is necessary, OCT-A might not be the most suitable method to dynamically evaluate the retinal microvasculature.