Date Published: March 15, 2019
Publisher: Public Library of Science
Author(s): Eun Kyoung Kim, Hae-Young Lopilly Park, Chan Kee Park, Augusto Paranhos.
To identify important variables associated with visual field (VF) defects in open-angle glaucoma (OAG) with myopia.
A total of 105 OAG with myopia were enrolled in this cross-sectional study. The disc tilt ratio, disc torsion degree, disc-foveal angle, and area of peripapillary atrophy (PPA) were measured from red-free fundus photographs. Patients underwent Swept-source optical coherence tomography to measure peripapillary retinal nerve fiber layer (RNFL), subfoveal choroidal, and sufoveal scleral thicknesses. Functional evaluation was performed using 24–2 standard automated perimetry. For statistical analyses, logistic regression, artificial neural networks (ANN), and hierarchical cluster analysis were performed.
Logistic regression demonstrated peripapillary RNFL thickness as a significant variable for the presence of VF defects, otherwise ANN identified PPA area, peripapillary RNFL thickness, disc-foveal angle, and disc torsion degree as significant clinical variables in OAG with myopia. Two clusters were made after a hierarchical cluster analysis. Cluster 2 showed significantly worse VF damage than cluster 1 (MD = -5.20±5.25 dB for cluster 2 and -1.84±3.02 dB for cluster 1, P < .001). Cluster 2 had significantly greater disc tilt ratio, disc-foveal angle, and PPA area compared with cluster 1 (P < .001, 0.005, and < .001, respectively). Generally peripapillary RNFL thickness is considered as an important variable associated with visual field defects in glaucoma patients. ANN identified parameters associated with posterior scleral deformations around optic disc induced by myopic change including PPA area, disc torsion degree, and disc-foveal angle as significant clinical variables for visual field damage in OAG with myopia.
Myopia has been shown to be a risk factor for the development of glaucoma in meta-analyses of epidemiological surveys [1–3]. There have been numerous explanations for the possible relationship between myopic eyes and glaucoma, and the percentage of myopia, especially high myopia, is high in asian populations, it is important to better understand the relationships between myopia and glaucoma. However, glaucoma specialists have great challenges to evaluate glaucoma patients with myopia, since many of the optic discs of myopic patients are accompanied by posterior architecture deformation showing disc tilt, torsion, or peripapillary atrophy (PPA).
A total of 105 eyes of 105 OAG patients with myopia were enrolled in this cross-sectional study. We retrospectively reviewed the medical records of 105 patients by two glaucoma specialist (EKK, CKP) between December 2014 and August 2017 at the glaucoma clinic of Seoul St. Mary’s Hospital. The study was performed with the informed consent of the participants and followed all of the guidelines for investigation in human subjects required by the Institutional Review Board of Seoul St. Mary’s Hospital. All investigations were performed in accordance with the Declaration of Helsinki.
This study involved 105 OAG eyes with myopia. The demographics of subjects with open-angle glaucoma are summarized in Table 1. There were excellent agreement between two graders for measurements of variables. The intraclass correlation coefficients (ICCs) for the measurements of the center of optic disc and subfoveal scleral thickness were 0.961 (95% CI, 0.931–0.990) and 0.954 (95% CI, 0.934–0.986) respectively.
Evaluating glaucoma in myopia poses great challenges for glaucoma specialists. The main aims of this study were identifying important clinical variables associated with visual field defects in OAG patients with myopia. In this study, artificial neural networks (ANN) strategy identified PPA area, peripapillary RNFL thickness, disc-foveal angle, and disc torsion degree as important clinical variables of visual field defects in OAG patients with myopia. Additionally we performed a hierarchical cluster analysis to subdivide OAG patients with myopia, and disc tilt ratio, disc-foveal angle, and PPA area were identified as significant variables to separate clusters. Collectively, our results suggest that variables of posterior scleral deformations around optic disc induced by myopic change are significantly associated with visual field damage in OAG patients with myopia