Correspondence: Brian C. Samuels, ; [e-mail]. PURPOSE. both model anatomy, anatomy purpose

• Type of Material: Article
• Authors: Jessica Jasien, University of Alabama Birmingham; Thomas A Read, Georgia Institute of Technology; Joseph Van Batenburg-Sherwood, Imperial College London; Kristin M Perkumas, Duke University; Christopher Ethier, Emory University; Daniel W Stamer, Duke University; Brian C Samuels, University of Alabama Birmingham
• Language: English
• Date: 2022-01-01
• 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.63.1.21
• Title of Journal or Parent Work: INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE
• Volume: 63
• Issue: 1
• Start Page: 21
• End Page: 21
• Grant/Funding Information: Supported by NIH/NEI grants R01 EY027759, EY030071, EY031710, EY028608 and EY022359, P30 EY003039, and both an unrestricted grant from Research to Prevent Blindness (RPB) to UAB as well as an RPB Physician-Scientist Award (Samuels).
• Keywords: aqueous outflow; RHESUS; GANGLION-CELLS; PERFUSION OUTFLOW FACILITY; INTRAOCULAR-PRESSURE; aqueous humor facility; histology; Ophthalmology; RESISTANCE; AQUEOUS-HUMOR DYNAMICS; WASHOUT; ANTERIOR-CHAMBER PERFUSION; EYE; Life Sciences & Biomedicine; Science & Technology; Tree Shrew; anterior; MONKEY; Anterior segment anatomy and
• Research Categories: Health Sciences, Opthamology; Engineering, Biomedical

Abstract

PURPOSE. Rodent and primate models are commonly used in glaucoma research; however, both have their limitations. The tree shrew (Tupaia belangeri) is an emerging animal model for glaucoma research owing in part to having a human-like optic nerve head anatomy, specifically a collagenous load-bearing lamina. However, the anterior segment anatomy and function have not been extensively studied in the tree shrew. Thus, the purpose of this study was to provide the first detailed examination of the anterior segment anatomy and aqueous outflow facility in the tree shrew. METHODS. Aqueous outflow dynamics were measured in five ostensibly normal eyes from three tree shrews using the iPerfusion system over a range of pressures. Gross histological assessment and immunohistochemistry were performed to characterize anterior segment anatomy and to localize several key molecules related to aqueous outflow. RESULTS. Anterior segment anatomy in tree shrews is similar to humans, demonstrating a scleral spur, a multilayered trabecular meshwork and a circular Schlemm's canal with a single lumen. Average outflow facility was 0.193 μL/min/mm Hg (95% confidence interval, 0.153-0.244), and was stable over time. Outflow facility was more similar between contralateral eyes (approximately 5% average difference) than between eyes of different animals. No significant dependence of outflow facility on time or pressure was detected (pressure-flow nonlinearity parameter of 0.01 (95% % confidence interval, -0.29 to 0.31 CI μL/min/mm Hg). CONCLUSIONS. These studies lend support to the usefulness of the tree shrew as a novel animal model in anterior segment glaucoma and pharmacology research. The tree shrew's cost, load-bearing collagenous lamina cribrosa, and lack of washout or anterior chamber deepening provides a distinct experimental and anatomic advantage over the current rodent and nonhuman primate models used for translational research.