Analysis of the Optic Nerve Head Microcirculation Using Optical Coherence Tomography Angiography and the Upstream Macrocirculation Using Color Doppler Imaging in Low-Tension and High-Tension Glaucoma Patients

Abstract

Introduction: To analyze the optic nerve head (ONH) microcirculation using optical coherence tomography angiography (OCT-A) and the upstream macrocirculation using color Doppler imaging (CDI) in low-tension and high-tension glaucoma (LTG and HTG, respectively). Methods: This cross-sectional study included 67 eyes of 67 HTG patients, 55 eyes of 55 LTG patients, and 42 eyes of 42 healthy controls. We recorded the complete ophthalmological examination, visual fields, retinal nerve fiber layer (RNFL) thickness, ONH vessel density (VD) measured using OCT-A, peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI) measured using CDI. SPSS software was used for data analysis. Data are presented as mean ± standard deviation or median (interquartile range) and compared using t-test or Mann-Whitney U test, as appropriate. Pearson chi-square test or Fisher’s exact test was used for comparisons, as appropriate. Pearson correlation analysis was used to evaluate for the correlations between variables. P < 0.05 was considered statistically significant. Results: The ONH VD and RNFL thickness were considerably lower in glaucomatous eyes than in healthy eyes (both p < 0.001). Compared with the HTG group, the LTG group had lower VD in the peripapillary region (p = 0.027). Compared with the healthy group, the HTG group had lower PSV (p = 0.029 and = 0.023, respectively), lower EDV (p = 0.023 and < 0.001, respectively), and higher RI (p = 0.019 and = 0.006, respectively) of internal carotid artery (ICA) and central retinal artery (CRA). The LTG group had lower PSV (p = 0.015 and < 0.001, respectively) and EDV (p = 0.047 and = 0.001, respectively) of ophthalmic artery (OA) and CRA. The LTG group had lower PSV of CRA than the HTG group (p = 0.034). In glaucomatous eyes, peripapillary VD had a significant association with the mean defect (MD) (p < 0.001) and RNFL thickness (p < 0.001), but not with the other CDI indices (all p > 0.05). Conclusion: The ONH microcirculation and upstream macrocirculation of the large arteries exhibited differences in the blood flow characteristics between the LTG and HTG groups. These differences may improve our understanding of glaucoma. There was no correlation between the characteristics of the ONH microcirculation and the upstream macrocirculation of large vessels in the LTG and HTG groups

Morphological and vascular evidence of glaucomatous damage in myopic guinea pigs with scleral crosslinking

“…For example, during deterioration in diabetic retinopathy, microvascular defects in the ONH may occur earlier than cpRNFL thinning 10 . Moreover, glaucomatous eyes have a significantly lower thickness of cpRNFL and vascular density of ONH compared with normal control eyes 11 . This study is the first to investigate the blood flow signal patterns of the guinea pig ONH to assess ONH ischemia under high IOP.…”

Current State of Knowledge in Ocular Blood Flow in Glaucoma: A Narrative Review

“…52 Doppler OCT has become a new imaging biomarker in ophthalmology for studying and diagnosing retinal vascular disorders, by providing detailed and quantitative information about blood flow dynamics in the retina, allowing for earlier detection and more accurate monitoring of various ocular conditions especially glaucoma. 53 The drawbacks include the compromised image quality due to the phase artifacts that occur in vessels with high BF velocities, and being sensitive to BF parallel to the OCT beam. 54…”

“…Doppler OCT has become a new imaging biomarker in ophthalmology for studying and diagnosing retinal vascular disorders, by providing detailed and quantitative information about blood flow dynamics in the retina, allowing for earlier detection and more accurate monitoring of various ocular conditions especially glaucoma. 53 …”