The role of blood pressure in glaucoma

Abstract

Although intraocular pressure (IOP) remains an important risk factor for glaucoma, it is clear that other factors can also influence disease development and progression. More recently, the role that blood pressure (BP) has in the genesis of glaucoma has attracted attention, as it represents a clinically modifiable risk factor and thus provides the potential for new treatment strategies beyond IOP reduction. The interplay between blood pressure and IOP determines the ocular perfusion pressure (OPP), which regulates blood flow to the optic nerve. If OPP is a more important determinant of ganglion cell injury than IOP, then hypotension should exacerbate the detrimental effects of IOP elevation, whereas hypertension should provide protection against IOP elevation. Epidemiological evidence provides some conflicting outcomes of the role of systemic hypertension in the development and progression of glaucoma. The most recent study showed that patients at both extremes of the blood pressure spectrum show an increased prevalence of glaucoma. Those with low blood pressure would have low OPP and thus reduced blood flow; however, that people with hypertension also show increased risk is more difficult to reconcile. This finding may reflect an inherent blood flow dysregulation secondary to chronic hypertension that would render retinal blood flow less able to resist changes in ocular perfusion pressure. Here we review both clinical and experimental studies that have attempted to clarify the relationships among blood pressure, OPP and blood flow autoregulation in the pathogenesis of glaucoma.

Regulation of Optic Nerve Head Blood Flow during Combined Changes in Intraocular Pressure and Arterial Blood Pressure

“…[33][34][35] A complete description of the theory how low OPP may be involved in glaucoma pathogenesis has been summarized in recent reviews. 36,37 With regard to the present data, it is of interest that ONHBF appears to have relatively little regulatory capacity when IOP is increased.…”

Mechanism of Aqueous Humor Secretion, Its Regulation and Relevance to Glaucoma

“…One hypothesis is the compromised blood supply to the optic nerve due to mechanical compression exerted by high IOP. There is evidences that suggests tissue hypoxia in the retina may affect the survival ganglion cells (He et al, 2011;Tezel and Wax, 2004). Other hypothesis includes oxidative or nitrative stress, both at the level of trabecular meshwork (Sacca et al, 2007) and 21 retinal ganglion cells (Aslan et al, 2008;Tezel, 2006); autoimmune reactions in which an individual's immune system facilitate somatic/axonal degeneration of retinal ganglion cells (Wax and Tezel, 2009); glutamate toxicity (Vorwerk et al, 1999); loss of neurotrophic factors (Pease et al, 2000), etc.…”

Prevalence of Glaucoma in Type 2 Diabetes Mellitus and Its Relation to Hypertension

“…3,9 Patients at both extremes of blood pressure spectrum show an increased prevalence of glaucoma. 10,11 The incidence is more for high-tension glaucoma. 12 Recent studies have also demonstrated that the effects on the visual field due to elevation of intraocular pressure was related to diastolic ophthalmic artery pressure.…”