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

Jialiu Lin,Zhonghao Wang,Jianan Xu,Chuchen Chung,Jingjing Huang,Miaomiao Dai,Bang V Bui

doi:10.1371/journal.pone.0177769

Jialiu Lin, Zhonghao Wang + Show 5 more

Open Access

https://doi.org/10.1371/journal.pone.0177769

Copy DOI

Journal: PloS one	Publication Date: May 18, 2017
Citations: 16	License type: CC BY 4.0

Affiliation: Sun Yat-sen University

Abstract

PurposeTo 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.MethodsConsecutive 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.ResultsFifty-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.ConclusionsDynamic 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.

Highlights

Primary angle-closure glaucoma (PACG) is a major cause of blindness globally, but especially in Asia [1,2]
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 chronic primary angle-closure glaucoma (CPACG) eyes than fellow PACS/primary angle closure (PAC) eyes and normal eyes (P
Pupil diameter change was largest in normal eyes, and larger in PACS/PAC eyes than CPACG eyes (P

Summary

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 [3,4,5]. Recent studies suggest that PAC pathogenesis depends on these static anatomic factors and on different dynamic responses of the anterior chamber under light and dark conditions [6,7,8,9,10]. Anterior segment optical coherence tomography (AS-OCT) [6,7,8,9,10] 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

Methods

Results

Conclusion