The relationship between plasma and aqueous humor endothelin-1 levels and retinal microvascular structure in glaucoma

PurposeTo explore the relationship between plasma and aqueous humor (AH) endothelin-1 (ET-1) levels and retinal microvascular parameters measured by optical coherence tomography angiography (OCT-A) in pseudoexfoliative glaucoma (XFG) and primary open-angle glaucoma (POAG) patients versus controls.MethodsThe plasma and AH ET-1 levels were assessed using enzyme-linked immunosorbent assay (ELISA) in 23 patients with XFG, 20 patients with POAG and 34 control subjects who underwent elective cataract surgery. Microvascular parameters in the optic disc and macula were measured by OCT-A four months after surgery. The relationship between plasma and AH ET-1 levels and OCT-A parameters was analysed.ResultsThis study included 77 eyes of 77 participants. The XFG group had higher AH ET-1 levels compared to both control (p = 0.009) and POAG (p = 0.004) groups, whereas the POAG and control groups were similar (p = 0.999). Negative correlation was found between AH ET-1 levels and whole, parafoveal, perifoveal superficial capillary plexus vascular density (SCP VD) (p < 0.05 for all) and whole, peripapillary, superior hemisphere, inferior hemisphere, inferior temporal radial peripapillary capillary vascular density (RPC VD) (p < 0.05 for all). The plasma ET-1 levels did not differ significantly among the groups (p = 0.161), and no statistically significant correlation was observed between the plasma ET-1 levels and any OCT-A parameter.ConclusionWhile plasma ET-1 levels showed no differences between groups or correlation with OCT-A parameters, elevated AH ET-1 levels in XFG and their strong correlation with OCT-A vascular parameters suggest that the intraocular effects of ET-1 may be more significant than its systemic effects in XFG pathogenesis.