Age and Menopause Effects on Ocular Compliance and Aqueous Outflow

• Type of Material: Article
• Authors: Andrew Feola, Emory University; Joseph M. Sherwood, Imperial College London; Machelle Pardue, Emory University; Darryl R. Overby, Imperial College London; Christopher Ethier, Emory University
• Language: English
• Date: 2020-05-01
• Publisher: ARVO Publicaions Inc.
• Publication Version: Final Published Version
• Copyright Statement: © 2020 The Authors.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1167/iovs.61.5.16
• Title of Journal or Parent Work: Investigative Ophthalmology & Visual Science
• Volume: 61
• Issue: 5
• Start Page: 16
• End Page: 16
• Grant/Funding Information: Supported by a Department of Veterans Affairs Rehabilitation Research & Development (RR&D) Service Career Development Award (RX002342A [AJF]) and a Department of Veterans Affairs RR&D Service Senior Research Career Scientist Award (RX003134 [MTP]); As well as by the Georgia Research Alliance (CRE), Royal Academy of Engineering (JMS) and the National Institutes of Health (EY022359 [DRO]).
• Keywords: Life Sciences & Biomedicine; outflow facility; Biomechanics; mechanics; Intraoccular pressure; Estrogen; ocular compliance; glaucoma; menopause; Science & Technology; Hormone replacement therapy; Ophthalmology
• Research Categories: Physics, Optics; Health Sciences, Opthamology; Health Sciences, Health Care Management

Abstract

Purpose Glaucoma is the second leading cause of blindness worldwide. Recent work suggests that estrogen and the timing of menopause play a role in modulating the risk of developing glaucoma. Menopause is known to cause modest changes in intraocular pressure; yet, whether this change is mediated through the outflow pathway remains unknown. Menopause also affects tissue biomechanical properties throughout the body; however, the impact of menopause on ocular biomechanical properties is not well characterized. Methods Here, we simultaneously assessed the impact of menopause on aqueous outflow facility and ocular compliance, as a measure of corneoscleral shell biomechanics. We used young (3–4 months old) and middle-aged (9–10 months old) Brown Norway rats. Menopause was induced by ovariectomy (OVX), and control animals underwent sham surgery, resulting in the following groups: young sham (n = 5), young OVX (n = 6), middle-aged sham (n = 5), and middle-aged OVX (n = 5). Eight weeks postoperatively, we measured outflow facility and ocular compliance. Results Menopause resulted in a 34% decrease in outflow facility and a 19% increase in ocular compliance (P = 0.011) in OVX animals compared with sham controls (P = 0.019). Conclusions These observations reveal that menopause affects several key physiological factors known to be associated with glaucoma, suggesting that menopause may contribute to an increased risk of glaucoma in women.