The Association between Vascular Abnormalities and Glaucoma—What Comes First?

Abstract

Glaucoma is a leading cause of irreversible blindness worldwide. While intraocular pressure (IOP) presents a major risk factor, the underlying pathophysiology still remains largely unclear. The correlation between vascular abnormalities and glaucoma has been deliberated for decades. Evidence for a role played by vascular factors in the pathogenesis of glaucomatous neurodegeneration has already been postulated. In addition, the fact that glaucoma causes both structural and functional changes to retinal blood vessels has been described. This review aims to investigate the published evidence concerning the relationship between vascular abnormalities and glaucoma, and to provide an overview of the “chicken or egg” dilemma in glaucoma. In this study, several biomarkers of glaucoma progression from a vascular perspective, including endothelin-1 (ET-1), nitric oxide, vascular endothelial growth factor (VEGF), and matrix metalloproteinases (MMPs), were identified and subsequently assessed for their potential as pharmacological intervention targets.

The Impact of Aging on the Function of Retinal Ganglion Cells

“…Changes in the ocular vascular dynamics with increasing age were found in the ophthalmic artery [60], central retinal artery [61], and the optic nerve head [62]. Vascular insufficiency may result in impaired oxygen and nutrient supply to RGCs [6,63].…”

“…The prevalence of systemic diseases, including diabetes mellitus, arterial hypertension, and dyslipidemia, increases with age [64]. These conditions might exacerbate important driving factors of aging, such as vascular insufficiency, which further impairs RGC nutrient supply and function [63].…”

Cardiac Surgery Patients Have Reduced Vascularity and Structural Defects of the Retina Similar to Persons with Open-Angle Glaucoma

“…Glaucomatous damage leads to distinctive visual field defects, which can progress to irreversible vision loss [ 1 , 2 ]. OAG is a leading cause of irreversible blindness worldwide and, despite years of research, its complex pathogenesis has not yet been fully elucidated [ 3 , 4 ].…”

“…Elevated intraocular pressure (IOP) is the only modifiable risk factor for OAG, and its reduction by medical and surgical means represents the mainstay of glaucoma treatment [ 4 , 5 , 6 ]. Elevated IOP can lead to compression of the optic nerve fiber bundles in the ONH, which interrupts its axoplasmic flow and causes the death of damaged RGCs [ 7 , 8 ].…”

“…However, elevated IOP does not explain glaucoma onset in patients with normal IOP (normal tension glaucoma), or disease progression in glaucoma patients with adequate IOP control [ 9 , 10 ]. Growing evidence suggests that ocular and systemic vascular risk factors play an important role in OAG development [ 4 , 10 ]. A large body of evidence demonstrated that a reduction in ocular blood flow may cause ischemic damage and lead to the death of RGCs and structural changes in the ONH [ 6 , 11 ].…”