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Blood flow parameters of the optic nerve

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Abstract:

Impaired ocular circulation in several ocular vascular beds has been widely investigated over decades and
has been shown to be a significant contributory physiological process in glaucomatous optic neuropathy.
Blood flow disturbances may occur primary in isolation or in combination with intraocular pressure (IOP) fluctuations. Glaucoma has long been associated with vascular diseases such as systemic hyper/hypo-tension,
diabetes, and migraine and dozens of prospective studies have found low ocular blood flow in glaucoma
patients. Many large population-based studies have reported low ocular perfusion pressures to be a risk
factor for prevalence, incidence, and progression of glaucoma. The contribution of ischemic damage in
glaucoma may be local, confined within the retina and anterior optic nerve, or may represent only one aspect
of a more generalized ischemic process. Specifically, the exact relationship of blood flow disturbances in
optic nerve tissues to glaucoma progression remains insufficiently described, as modalities capable of imaging the optic nerve’s vasculature beds have been historically limited in their ability to provide meaningful outcomes. Many technologies provide some measure of perfusion, but have significant limitations in direct measurements of optic nerve hemodynamics. Mathematical modeling in combination with clinical data has provided some theory as to how changes in IOP, global perfusion, and optic nerve head (ONH) blood flow might affect ocular structure and retinal ganglion cell survival. Recent advances in imaging technologies such as optical coherence tomography angiography are providing new and impactful findings of blood flow in optic nerve tissues and relevance to glaucoma pathophysiology. Herein, vascular considerations including technologies used to assess blood flow disturbances in the optic nerve tissues and ONH are reviewed, and discussion on future targets and clinical relevance in glaucomatous optic neuropathy are presented.

Glaucoma Research 2018-2020, pp. 133-149 #10
Edited by: John R. Samples and Paul A. Knepper
© Kugler Publications, Amsterdam, The Netherlands

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