Dynamic changes of anterior segment in patients with different stages of primary angle-closure in both eyes and normal subjects

RESEARCH ARTICLE Dynamic changes of anterior segment in patients with different stages of primary angle-closure in both eyes and normal subjects Jialiu Lin☯, Zhonghao Wang☯, Chuchen Chung, Jianan Xu, Miaomiao Dai, Jingjing Huang* a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China ☯ These authors contributed equally to this work. * Abstract OPEN ACCESS Citation: Lin J, Wang Z, Chung C, Xu J, Dai M, Huang J (2017) Dynamic changes of anterior segment in patients with different stages of primary angle-closure in both eyes and normal subjects. PLoS ONE 12(5): e0177769. https://doi. org/10.1371/journal.pone.0177769 Purpose To compare changes in anterior segment parameters under light and dark (light-to-dark) conditions among eyes with chronic primary angle-closure glaucoma (CPACG), fellow eyes with confirmed or suspect primary angle-closure (PAC or PACS), and age-matched healthy eyes. Editor: Bang V Bui, University of Melbourne, AUSTRALIA Received: June 20, 2016 Methods Accepted: May 3, 2017 Consecutive patients with CPACG in one eye and PAC/PACS in the fellow eye, as well as age-matched healthy subjects were recruited. Anterior segment optical coherence tomography measurements were conducted under light and dark conditions, and anterior chamber, lens, and iris parameters compared. Demographic and biometric factors associated with light-to-dark change in iris area were analyzed by linear regression. Published: May 18, 2017 Copyright: © 2017 Lin et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Funding: This work is supported by the Research Grant 201607010321 from Guangzhou Science Technology and Innovation Commission in China. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The URLs of the funder is http://wsbs.gzsi.gov.cn/login.html. This work is also supported by Grant 2013B022000037 Results Fifty-seven patients (mean age 59.6±8.9 years) and 30 normal subjects matched for age (60.6±9.3 years) and sex ratio were recruited. In regards to differences under light–to-dark conditions, angle opening distance at 500 μm (AOD500μm) and iris area during light-to-dark transition were smaller in CPACG eyes than fellow PACS/PAC eyes and normal eyes (P<0.017). Pupil diameter change was largest in normal eyes, and larger in PACS/PAC eyes than CPACG eyes (P<0.017). There was an average reduction of 0.145 mm2 in iris area for each millimeter of pupil diameter increase in CPACG eyes, 0.161 mm2 in fellow PAC/PACS eyes, and 0.165 mm2 in normal eyes. Larger iris curvature in the dark and diagnosis of PACG were significantly associated with less light-to-dark iris area changes. PLOS ONE | https://doi.org/10.1371/journal.pone.0177769 May 18, 2017 1 / 15 Dynamic changes of anterior segment in PACG eyes and their fellow eyes from Science and Technology Planning Project of Guangdong Province in China. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The URLs of the funder is http://pro. gdstc.gov.cn/egrantweb/. Conclusions Dynamic changes in iris parameters with light-to-dark transition differed significantly among CPACG eyes, fellow PAC/PACS eyes, and normal eyes. Greater iris curvature under dark conditions was correlated with reduced light-to-dark change in iris area and pupil diameter, which may contribute to disease progression. Competing interests: The authors have declared that no competing interests exist. Introduction Primary angle-closure glaucoma (PACG) is a major cause of blindness globally, but especially in Asia [1,2]. Most ocular biometry studies of PACG have compared patients to normal subjects or acute primary angle closure (PAC) eyes to unaffected fellow eyes. Such studies have revealed much about the risk factors and pathogenesis of PACG. Shallow anterior chamber depth (ACD), short axial length (AL), greater lens thickness (LT), and larger lens vault (LV) are risk factors for PACG [3–5]. In addition, recent studies suggest that PAC pathogenesis depends not only on these static anatomic factors but also on different dynamic responses of the anterior chamber under light and dark conditions [6–10]. Anterior segment optical coherence tomography (AS-OCT) [6–10] and ultrasound biomicroscopy (UBM) [11] can provide high-definition images of the anterior segment in vivo, yielding reliable and repeatable quantitative measurements for assessing dynamic changes. The classification for PAC includes primary angle closure suspect (PACS), PAC, and PACG [12]. The spectrum of disease could be regarded as: progression from PACS to PAC, then to PACG. However, the risk factors contributing to disease progression are not wellunderstood. Our previous study using UBM showed that a thin and anteriorly bowed iris may be associated with greater risk of progression from PAC/PACS to chronic PACG (CPACG) [13]. In the current study, we consider whether dynamic changes in anterior segment parameters are related to the asymmetry of disease development between the two eyes of CPACG patients. The objective was twofold: 1) to assess whether eyes at different stages of PAC exhibit different light-to-dark anterior segment changes; 2) to assess associations between these changes and demographic and ocular biometric parameters. Materials and methods Participants and ocular examinations This is a cross-sectional comparative study. Consecutive patients diagnosed by two glaucoma specialists (JH & ZW) with CPACG in one eye and either confirmed or suspected primary angle-closure (PAC or PACS, respectively) in the fellow eye were recruited. Age and sexmatched healthy controls were recruited. The study was conducted at the Department of Glaucoma, Zhongshan Ophthalmic Center of Sun Yat-sen University (Guangzhou, China) from January 2014 to January 2015. CPACG, PAC, PACS were defined according to International Society of Geographical and Epidemiological Ophthalmology (ISGEO) classifications [12]. Briefly, PACS is diagnosed when greater than 270˚ of the posterior trabecular meshwork is not visible on gonioscopy, while PAC is PACS associated with peripheral anterior synechiae (PAS) and/or elevated intraocular pressure (IOP) without glaucomatous damage of the optic nerve, and CPACG is PAC with evidence of optic nerve damage. PAC and CPACG eyes must not exhibit symptoms or signs of acute angle closure attack such as "glaukomflecken" or iris sphincter palsy. In this PLOS ONE | https://doi.org/10.1371/journal.pone.0177769 May 18, 2017 2 / 15 Dynam (...truncated)