A Potential Role of Acute Choroidal Expansion in Nonarteritic Anterior Ischemic Optic Neuropathy

• Type of Material: Article
• Authors: Andrew Feola, Emory University; Christopher A Girkin, University of Alabama Birmingham; Christopher Ethier, Emory University; Brian C Samuels, University of Alabama Birmingham
• Language: English
• Date: 2022-04-01
• Publisher: ASSOC RESEARCH VISION OPHTHALMOLOGY INC
• Publication Version: Final Published Version
• Copyright Statement: © 2022 The Authors
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1167/iovs.63.4.23
• Title of Journal or Parent Work: INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE
• Volume: 63
• Issue: 4
• Start Page: 23
• End Page: 23
• Grant/Funding Information: Supported by a Department of Veterans Affairs Rehabilitation Research & Development (RR&D) Service Career Development Award (RX002342A; to A.J.F.), the Georgia Research Alliance (C.R.E.), and an unrestricted Research to Prevent Blindness grant (B.C.S. and C.A.G.), EyeSight Foundation of Alabama (C.A.G.).
• Keywords: ocular biomechanics; OCULAR PULSE; computational modeling; PSEUDOTUMOR CEREBRI SYNDROME; nonarteritic anterior ischemic optic neuropathy; BIOMECHANICAL PROPERTIES; REVISED DIAGNOSTIC-CRITERIA; glaucoma; Science & Technology; NERVE HEAD; DEFORMATION; choroid; Ophthalmology; intracranial pressure; IOP TELEMETRY; MORPHOLOGY; ANGIOGRAPHY; COHERENCE TOMOGRAPHY; finite element modeling; Life Sciences & Biomedicine

Abstract

PURPOSE. Nonarteritic anterior ischemic optic neuropathy (NAION) has been associated with a thickened choroid at the optic nerve head (ONH). Here, we use computational modeling to better understand how choroidal expansion and choroidal geometry influence tissue deformation within the ONH relative to intraocular pressure (IOP) and intracranial pressure (ICP) effects. METHODS. Using a model of the posterior eye that included the sclera, peripapillary sclera, annular ring, pia mater, dura mater, neural tissues, Bruch’s membrane, choroid, and lamina cribrosa, we examined how varying material properties of ocular tissues influenced ONH deformations under physiological and supra-physiological, or “pathological,” conditions. We considered choroidal expansion (c. 35 μL of expansion), elevated IOP (30 mm Hg), and elevated ICP (20 mm Hg), and calculated peak strains in the ONH relative to a baseline condition representing an individual in the upright position. RESULTS. Supra-physiological choroidal expansion had the largest impact on strains in the prelaminar neural tissue. In addition, compared to a tapered choroid, a “blunt” choroid insertion at the ONH resulted in higher strains. Elevated IOP and ICP caused the highest strains within the lamina cribrosa and retrolaminar neural tissue, respectively. CONCLUSIONS. Acute choroidal expansion caused large deformations of the ONH and these deformations were impacted by choroid geometry. These results are consistent with the concept that compartment syndrome due to the choroid geometry and/or expansion at the ONH contributes to NAION. Prolonged deformations due to supra-physiological loading may induce a mechanobiological response or ischemia, highlighting the potential impact of choroidal expansion on biomechanical strains in the ONH.