Intracellular Flow in Optic Nerve Axons: A Mechanism for Cell Death in Glaucoma

PURPOSE. In glaucoma, elevated intraocular pressure causes a progressive loss of retinal ganglion cells and results in optic neuropathy. The authors propose a potential mechanism for cell death, whereby elevated intraocular pressure causes fluid to per-meate axonal membranes, creating a passive intracellular fluid flow within the axons. It is hypothesized that this intracellular flow locally depletes the adenosine triphosphate (ATP) concen-tration, disrupting axonal transport and leading to cell death. METHODS. A mathematical model was developed that takes into account the biomechanical principles underpinning the pro-posed hypothesis, and was solved to determine the implica-tions of the mechanism. RESULTS. The model suggests that the raised intraocular pres-sures present in glaucoma are adequate to produce significant intracellular fluid flow. In the periphery of the optic nerv