Comparison of optical coherence tomography angiography metrics in primary angle-closure glaucoma and normal-tension glaucoma

Abstract

To investigate the peripapillary vascular metrics in early normal tension glaucoma (NTG) and early primary angle closure glaucoma (PACG) eyes using optical coherence tomography angiography (OCT-A). One or both eyes of each subject were imaged for a 3 × 3 mm peripapillary region by swept-source OCT-A (DRI-OCT Triton, Topcon, Japan) and assessed by an automated MATLAB program. OCT-A metrics including circumpapillary vessel density (cpVD) and fractal dimension (cpFD) were compared. Their association with visual field (VF) parameters and retinal nerve fiber layer (RNFL) thickness were determined. Sixty-eight eyes of 51 PACG, 68 eyes of 48 NTG, and 68 eyes of 49 control subjects were cross-sectionally analyzed. NTG eyes had significantly lower global cpVD (52.369 ± 0.781%) compared with PACG eyes (55.389 ± 0.721%, P = 0.004) that had comparable disease severity and average RNFL thickness. Multivariable analysis revealed that, for PACG and NTG eyes, decreased cpVD ([PACG] β = −4.242; CI: −8.120, −0.363 vs [NTG] β = −5.531; CI: −9.472, −1.590) and cpFD ([PACG] β = −8.894;CI: −11.925, −5.864 vs [NTG] β = −12.064; CI: −17.095, −6.932) were associated with decreased RNFL thickness (all P ≤ 0.032); with a stronger association between decrease cpFD and decreased RNFL thickness in NTG eyes (P = 0.028). Decreased cpVD was associated with decrease mean deviation (MD) in NTG eyes (β = −0.707; CI: −1.090, −0.324; P ≤ 0.001) and not associated with the visual field parameters in PACG eyes. Early NTG had lower global cpVD compared with early PACG, despite similar disease severity and average RNFL thickness.

Risk Factors for Primary Angle-closure Glaucoma: A Systematic Review and Meta-analysis of 45 Studies

“…Advances in imaging diagnostic techniques have revealed more anatomical factors associated with primary angle-closure glaucoma, helping to develop a deeper understanding of disease pathology. The optic disc nerve and its vascular structures are important in the pathophysiology of primary angle-closure glaucoma 14,23,30,32 . In our meta-analysis, thinner retinal nerve fiber layer was significantly associated with primary angle-closure glaucoma.…”

“…1. Appendix Table A4, available at http://links.lww.com/OPX/A658, shows the characteristics of the remaining 45 related studies 12–56 . Two of the 45 articles were conducted from the same cohort 44,45 .…”

“…All of the qualities of the included studies were medium or good, except one case-control study conducted in 1990 47 . In total, 30 articles were available for meta-analysis, including 15 cross-sectional, 12–15,17,19–27,29 13 case-control, 32–36,38–43,45,46 and 2 longitudinal cohort studies 54,56 …”

“…The meta-analysis suggests that there is a significant association between retinal nerve fiber layer and primary angle-closure glaucoma (weighted mean difference, −21.23; 95% confidence interval, −30.21 to −12.25). Three cross-sectional studies 14,23,25 and three case-control studies 32,33,42 that assessed the relationship of spherical equivalent and primary angle-closure glaucoma were eligible for our analysis, and we found that increased spherical equivalent is significantly associated with primary angle-closure glaucoma (weighted mean difference, 1.02; 95% confidence interval, 0.66 to 1.38). The same results were revealed by the sensitivity analysis accounting for intraocular pressure, anterior chamber depths, and axial lengths (not shown).…”

Comparison of the Choroid in Primary Open Angle and Angle Closure Glaucoma Using Optical Coherence Tomography

“…A recent study found that among patients with POAG and PACG, both with elevated IOP, choroidal microvasculature dropout was greater in POAG, indicating a role for primary choroidal ischemic injury in the pathophysiology of POAG. 27 Another study by Shen et al 28 demonstrated that the reduction in circumpapillary vessel density was more pronounced in patients with normal tension glaucoma who had normal IOP than in patients with PACG who had high IOP. A study by Cheng et al 29 also showed that in the subgroup with the lowest IOP in POAG, the choriocapillaris vessel density decreased the fastest.…”