Comparison of the Abilities of SD-OCT and SS-OCT in Evaluating the Thickness of the Macular Inner Retinal Layer for Glaucoma Diagnosis

RESEARCH ARTICLE Comparison of the Abilities of SD-OCT and SS-OCT in Evaluating the Thickness of the Macular Inner Retinal Layer for Glaucoma Diagnosis Kyoung Min Lee1, Eun Ji Lee1*, Tae-Woo Kim1*, Hyunjoong Kim2 1 Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea, 2 Department of Applied Statistics, Yonsei University, Seoul, Korea * (EJL); (TWK) Abstract Purpose OPEN ACCESS Citation: Lee KM, Lee EJ, Kim T-W, Kim H (2016) Comparison of the Abilities of SD-OCT and SS-OCT in Evaluating the Thickness of the Macular Inner Retinal Layer for Glaucoma Diagnosis. PLoS ONE 11 (1): e0147964. doi:10.1371/journal.pone.0147964 Editor: Pedro Gonzalez, Duke University, UNITED STATES Received: June 22, 2015 Accepted: January 11, 2016 To compare the abilities of spectral-domain optical coherence tomography (OCT) (SD-OCT; Spectralis, Heidelberg Engineering) and swept-source OCT (SS-OCT; DRI-OCT1 Atlantis system, Topcon) for analyzing the macular inner retinal layers in diagnosing glaucoma. Methods The study included 60 patients with primary open-angle glaucoma (POAG) and 60 healthy control subjects. Macular cube area was scanned using SD-OCT and SS-OCT on the same day to assess the thicknesses of the macular retinal nerve fiber layer (mRNFL), ganglion cell layer plus inner plexiform layer (GCIPL), and total retinal layer in nine subfields defined by the Early Treatment Diabetic Retinopathy Study (ETDRS). The abilities of the parameters to discriminate between the POAG and control groups were assessed using areas under the receiver operating characteristic curves (AUCs). Published: January 26, 2016 Copyright: © 2016 Lee 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. Funding: This study was supported by a grant from the National Research Foundation of Korea funded by Korean Government (no. 2013R1A1A1A05004781). The funding organization had no role in the design or conduct of this research. Competing Interests: The authors have declared that no competing interests exist. Results Glaucoma-associated mRNFL and GCIPL thinning was more common in the outer zones than inner zones for both SD-OCT and SS-OCT. The mRNFL and GCIPL measurements showed distinct pattern differences between SD-OCT and SS-OCT in each ETDRS subfield. Although the glaucoma-diagnosis ability was comparable between SD-OCT and SSOCT for most of the parameters, AUC was significantly larger for SD-OCT measurements of the GCIPL thickness in the outer temporal zones (p = 0.003) and of the mRNFL thickness in the outer nasal zones (p = 0.001), with the former having the largest AUC for discriminating POAG from healthy eyes (AUC = 0.894). Conclusion Spectralis SD-OCT and DRI SS-OCT have similar glaucoma-diagnosis abilities based on macular inner layer thickness analysis. However, Spectralis SD-OCT was potentially PLOS ONE | DOI:10.1371/journal.pone.0147964 January 26, 2016 1 / 17 Comparison of SD-OCT and SS-OCT Macular Analysis superior to DRI SS-OCT in detecting GCIPL thinning in the outer temporal zone, where the glaucomatous damage predominantly occurs. Introduction Glaucoma is characterized by the progressive degeneration of retinal ganglion cells (RGC) and the loss of their axons [1,2]. Evaluating the number of RGC axons lost using optical coherence tomography (OCT) has been essential for diagnosing glaucoma and monitoring its progression [3–5]. In recent decades the peripapillary retinal nerve fiber layer (RNFL) has been a major focus in OCT-based glaucoma evaluations [4–7]. However, recent advances in OCT technology have enabled more detailed segmentation of the macular inner retinal layers, and thus allowed the quantitative evaluation of macular RGC damage [8–10]. Studies have shown that the thickness of the macular inner retinal layer as measured using spectral-domain OCT (SD-OCT) is useful for the diagnosis of early glaucoma [11–14] and for evaluating glaucoma progression [15–17]. In addition, potential advantages of macular analysis have also been suggested in patients with high myopia [18,19], parafoveal scotoma [20,21], and advanced disease [16,22]. New software that allows the segmentation of individual layers of the retina has been recently designed for the Spectralis OCT system (Heidelberg Engineering, Heidelberg, Germany) [23]. This enables the independent measurement of each of the retinal layers of the macula, including the macular RNFL (mRNFL) and ganglion cell layer (GCL). The usefulness of this algorithm in discriminating between glaucoma suspects and healthy subjects has recently been evaluated [23]. However, the glaucoma-diagnosis ability of this new algorithm has yet to be reported. On the other hand, a newer generation swept-source OCT (SS-OCT) system, called the DRI-OCT1 Atlantis system (Topcon, Tokyo, Japan), also has an automated algorithm for segmenting macular inner retinal layers, and provides the thicknesses of the mRNFL and the GCL plus inner plexiform layer (IPL) (GCIPL) in the macular area. Since SS-OCT penetrates deeper into the tissue and provides high-resolution images [24,25], the ability to measure the macular inner layer thicknesses using SS-OCT is also of interest in the diagnosis of glaucoma. It was found recently that the diagnostic ability was similar between measuring the RNFL thickness over the macular and peripapillary area using DRI SS-OCT and measuring the circumpapillary RNFL (cpRNFL) thicknesses using DRI SS-OCT or Spectralis SD-OCT [26]. More recently, the diagnostic abilities of DRI SS-OCT and Cirrus SD-OCT (Carl Zeiss Meditec, Dublin, CA, USA) in measuring the macular GCIPL thicknesses were also found to be similar [27]. However, the usefulness of DRI SS-OCT assessments of macular inner retinal layers in diagnosing glaucoma relative to using Spectralis SD-OCT has not been fully evaluated. The macular segmentation software programs provided with the Spectralis OCT and DRI-OCT1 Atlantis systems both have a sectorial thickness evaluation tool using the circle defined by the Early Treatment Diabetic Retinopathy Study (ETDRS), which allows a 1:1 comparison of the thickness in each sector between the two OCT systems. The present study aimed to determine and compare the glaucoma-diagnosis abilities of macular inner retinal layer analysis performed using SD-OCT and SS-OCT with the Spectralis OCT and DRI-OCT1 Atlantis systems, respectively. Materials and Methods Participants This prospective, cross-sectional study included patients with primary open-angle glaucoma (POAG) and age-matched healthy controls. Written informed consent to participate was PLOS ONE | DOI:10.1371/journal.pone.0147964 January 26, 2016 2 / 17 Compar (...truncated)