Blood flow in high-tension and normal-tension glaucoma

Increased intraocular pressure

Although elevated eye pressure is an important risk factor for glaucomatous optic neuropathy (GON), it is not the only one. Also important are impaired blood flow. These are not only a consequence of GON or high eye pressure; rather, there are primary circulatory disorders that are causally involved in the development of the damage. This is all the more important because these are usually treatable. In addition, high eye pressure leads to a reduction of blood flow when autoregulation is disturbed at the same time.
Correlations between intraocular pressure, visual field and visual acuity
P Niesel, J Flammer:
Correlations between intraocular pressure, visual field and visual acuity, based on 11 years of observations of treated chronic glaucomas
Intraocular pressure is not the focus of this webpage. However, we are asking here whether an increased eye pressure could damage the optic nerve not only mechanically, but also by reducing blood flow. Interestingly, very early studies by Niesel and Flammer have already shown that mainly eye pressure fluctuations contribute to visual field damage. If the autoregulation of ocular blood flow is overstrained or defective, blood flow fluctuates. The resulting fluctuations in oxygen supply increase oxidative stress in the mitochondria of the axons in the optic nerve head and thus contribute decisively to the development of GON.
Die quantitative Perimetrie beim Glaukompatienten ohne lokale Gesichtsfelddefekte
J Flammer, E Eppler, P Niesel:
Quantitative Perimetry in the Glaucoma Patient Without Local Visual Field Defects
Glaucoma leads not only to scotomas in the visual field, but also to diffuse visual field damage. In automatic static perimetry, this is manifested by a sinking of the Bebie curve. In manual kinetic perimetry, this is manifested by narrowing of the isopter. Flammer and Niesel have shown that the increase of this diffuse glaucoma damage correlates with the magnitude of the eye pressure fluctuation. This means the following: a) in glaucoma perimetry we should not only look for scotomas but also quantify the diffuse damage and b) in the treatment of eye pressure not only lowering but especially stabilizing is important.