==== Front Chin Med J (Engl)Chin. Med. JCMJChinese Medical Journal0366-6999Medknow Publications & Media Pvt Ltd India 30058579CMJ-131-181910.4103/0366-6999.237391Original ArticleEffectiveness of Glaucoma Diagnostic Parameters from Spectral Domain-Optical Coherence Tomography of Myopic Patients 频域光学相干成像青光眼诊断参数在近视眼中的诊断能 力分析 Fang Yuan 1Zhang Han-Qiao 2Qiao Rong-Hua 2Yao Xu-Yang 1Pan Ying-Zi 1Li Mei 11 Department of Ophthalmology, Peking University First Hospital, Beijing 100034, China2 Department of Ophthalmology, Beijing Tsinghua Changgung Hospital, Beijing 102218, ChinaAddress for correspondence: Dr. Rong-Hua Qiao, Department of Ophthalmology, Beijing Tsinghua Changgung Hospital, No. 168 Litang Road, Changping District, Beijing, China E-Mail: codanet@hotmail.com05 8 2018 131 15 1819 1826 08 2 2018 Copyright: © 2018 Chinese Medical Journal2018This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.Background: Currently, spectral-domain optical coherence tomography (SD-OCT) appears to be a new type of glaucoma diagnostic tool. Thus, this study aimed to evaluate the effectiveness of glaucoma diagnostic parameters from SD-OCT of patients with different severities of myopia. Methods: This was a cross-sectional study. A total of 248 participants (248 eyes) were enrolled, including 51 cases in the early primary open-angle glaucoma group, 79 cases in the control group (0.50 D to −0.50 D, excluding −0.50 D), 47 cases in the low-myopic group (−0.50 to −3.00 D, excluding −3.00 D), 43 cases in the moderate-myopic group (−3.00 to −6.00 D, excluding −6.00 D), and 28 cases in the high-myopic group (≤−6.00 D). All participants were examined using the Humphrey visual field test and SD-OCT. The SD-OCT parameters of the retinal nerve fiber layer (RNFL) and ganglion cell complex were analyzed statistically using the receiver operating characteristic curve and area under the curve (AUC). Results: The AUC showed that the best parameters for the control and low-myopic groups were the inferior and inferior temporal RNFL thicknesses (AUC >0.94), respectively; for the moderate- and high-myopic groups, the best parameter was the temporal low RNFL thickness (AUC, 0.926 and 0.896, respectively). The AUC of the inferior parameters of the moderate-myopic group (0.864) was lower, ranked 15th among all RNFL parameters. When the sensitivity was fixed at 85%, the specificity of the inferior, superior, inferior temporal, and superior temporal quadrants was higher (>80%) in the control and low-myopic groups, while they were lower (20–60%) for the moderate- and high-myopia groups. The green color based on the OCT database was also less for the high-myopic group compared with that of other groups (P < 0.05). Conclusions: Glaucoma diagnostic parameters from SD-OCT were not clinically effective for the moderate- and high-myopic groups. The specificities were low. The moderate- and high-myopic groups require comprehensive analyses for the diagnoses of glaucoma. The SD-OCT database should be improved to better indicate the level of myopia based on the corresponding diopter readings. 摘要 目的： 目前频域光学相干成像（SD-OCT）可作为青光眼诊断的新工具。因此本文评价了SD-OCT所提供的青光眼诊断参数在不同屈光度近视患者中的诊断能力。 方法： 横断面研究。共有248例受试者（248眼）入选。包括早期开角型青光眼组51，正常人组79例（±0.50D之内），低度近视组47例（−0.50 D to −3.00 D（不包括）），中度近视组43例（−3.00 D to −6.00 D（不包括）），高度近视组28例（≤−6.00 D）。所有受试者均行眼科常规检查及Humphrey 视野计、SD-OCT检查，将OCT检查所获得的视网膜神经纤维层(RNFL)和节细胞复合体（GCC））的相关参数进行统计学分析，分别绘制受试者操作曲线（ROC）并计算曲线下面积（AUC）。 结果： AUC结果如下：正常人、低度近视眼组的AUC最佳参数均为下方、颞下方RNFL厚度（AUC均>0.94），而中度近视、高度近视组的最佳参数均为颞下方参数（AUC分别为0.926，0.896），而中度近视组下方参数的AUC较小（0.864）排在所有RNFL参数的第15位。对文献中公认的诊断青光眼能力强的参数（下方、颞下方、颞上方）进行进一步分析，当灵敏度为85%时，这些参数在正视眼、低度近视眼组的特异度较高，均大于80%，而在中度近视、高度近视组特异度均较低，约在20%～60%。根据机器数据库所得绿色部分在高度近视组也较其他组少（P < 0.05）。 结论： SD-OCT的青光眼诊断参数在应用于中高度近视眼时的诊断能力较弱，特异度明显偏低，对中高度近视者进行青光眼的诊断时需综合分析。同时建议SD-OCT的正常人数据库应针对不同屈光度进行补充完善。 GlaucomaMyopiaNerve FibersOpen AngleRetina ==== Body INTRODUCTION Myopia has a very high prevalence and is an independent and significant risk factor for primary open-angle glaucoma (POAG).[1] However, an anomalous optic nerve head (ONH) caused by myopia makes glaucoma screening and early diagnosis difficult in myopic patients.[234] As a new type of glaucoma diagnostic tool, high-resolution spectral-domain optical coherence tomography (SD-OCT) can assist in the early diagnosis of glaucoma by quantitatively analyzing the ONH with excellent precision. However, it is not known whether the glaucoma diagnostic parameters from SD-OCT can accurately diagnose the changes in fundus related to myopia. At present, there are few studies reported in this area. We therefore determined whether SD-OCT could be used to more accurately diagnose patients with myopia and early glaucoma. METHODS Ethical approval This study was approved by the Ethics Committee of Peking University First Hospital. Consent was obtained from all patients, and the protocol followed the principles of the Declaration of Helsinki. Myopic and early glaucoma groups This was a cross-sectional study, satisfying the inclusion and exclusion criteria, which involved consecutive outpatients at the Department of Ophthalmology in our hospital, from October 2012 to June 2016. Normal control and myopic groups were recruited from October 2012 to March 2013. All POAG patients satisfied the following inclusion criteria: (1) A best-corrected visual acuity ≥20/30; (2) spherical refraction within −6.00 to 0 D and a cylinder correction within ±3.0 D, antimetropia ≤2 D; (3) open angles on gonioscopy and typical glaucomatous optic disc appearances such as rim thinning, notching, excavation, hemorrhage, or retinal nerve fiber layer (RNFL) defects; and (4) glaucomatous visual field (VF) loss on at least two separate occasions with mean deviations ≥−6 dB, with clusters of three or more adjacent points depressed more than 5 dB, or two or more adjacent points depressed more than 10 dB. The exclusion criteria were as follows: (1) eyes with coexisting retinal disease, optic neuropathy, uveitis, trauma and past intraocular surgery; (2) patients who had undergone eye-selective laser trabeculoplasty surgery within the past year; and (3) patients with a history of diabetes, hypertension, or other diseases that may have affected measurement results. Myopic patients satisfied all of the following inclusion criteria: (1) a best-corrected visual acuity ≥20/20; (2) a spherical refraction ≤−0.50 D, cylinder correction within ±3.0 D, and spherical refraction >1/2 cylinder correction; (3) normal slit-lamp and fundus examinations; (4) healthy optic disc appearance, a cup-to-disc ratio <0.6, no evidence of diffuse or focal rim thinning, cupping, optic disc hemorrhage, or RNFL defects, and an interocular asymmetry of a cup-to-disc ratio <0.2, with leopard fundus changes, arc spots, and other nonpathological myopic changes accepted; (5) Goldmann applanation tonometer ≤21 mmHg and a central corneal thickness 520–580 μm; (6) normal VFs with a Glaucoma Hemifield Test within normal limits; (7) no pathological myopia; and (8) no prior history of glaucoma or a glaucomatous family history. Eyes with coexisting retinal disease, optic neuropathy, uveitis, trauma, and past intraocular surgery were excluded, as well as those with a history of diabetes, hypertension, or other diseases that may have affected the measurement results. Controls satisfied all of the following inclusion criteria: (1) visual acuity ≥20/20; (2) a spherical refraction within ±0.50 D and a cylinder correction within ±0.75 D; and (3) all inclusion criteria of the myopic patients. History and routine ophthalmic examinations All patients underwent a full ophthalmic examination including visual acuity, refraction, intraocular pressure as measured using Goldmann applanation tonometry, gonioscopy, and a dilated fundus examination. Visual field testing All participants underwent SITA fast 24-2 perimetry (Humphrey perimetry, Humphrey Field Analyzer model 750; Carl Zeiss Meditec, Dublin, CA, USA). Minimal criteria for a glaucomatous VF defect were as follows: a Glaucoma Hemifield Test outside normal limits, a pattern standard deviation with P < 5%, or a cluster of ≥3 points in the pattern deviation plot in a single Hemifield (superior or inferior) with P < 0.05, one of which was P < 0.01. Any one of the preceding criteria, if repeatable, was considered sufficient evidence of a glaucomatous VF defect. A reliable VF test was defined as one with fewer than 30% fixation losses, false-positive responses, or false-negative responses. Fundus stereophotography Early-glaucoma patients underwent TRC-SS (Topcon, Tokyo, Japan) fundus stereophotography examination, which was completed by an experienced technician. Photographic results were interpreted by an experienced glaucoma specialist. Spectral domain-optical coherence tomography examinations SD-OCT examinations using the RTVue-100, version 6.1 (Optovue, Fremont, CA, USA), were performed on all patients. The patient was seated in a mandibular jaw frame, adjusted to the appropriate position using internal fixation, choosing a nationality of Chinese. Each patient was scanned using two patterns, including an ONH scan and ganglion cell complex (GCC) scan. Quality SD-OCT scans were defined as those with a signal strength index >40. The parameters used for the analysis of the ONH were as follows: SH, IH, S, I, N, T, NU, SN, ST, TU, TL, IT, IN, NL, NU1, NU2, SN2, SN1, ST1, ST2, TU2, TU1, TL1, TL2, IT2, IT1, IN1, IN2, NL2, and NL1 [Figure 1], and the parameters used for the analysis of the GCC were GCC-a, GCC-S, and GCC-I. Figure 1 The ONH parameters. ONH: Optic nerve head. Statistical analysis One eye from each participant was selected for the analysis. If a participant satisfied the criteria of both eyes, then in accordance with a random number table, one eye was selected for statistical analysis. The data were analyzed using SPSS statistical software for Windows (version 14.0, SPSS, Chicago, IL, USA). A value of P < 0.05 was considered statistically significant. A logistic regression model was used to correct for age and diopter. Receiver operating characteristic (ROC) curves for a parameter with significant differences according to logistic regression results were constructed. Data with a normal distribution are expressed as the mean ± standard deviation (SD). Data with an abnormal distribution are expressed as the median (minimum and maximum). The counted data are expressed as a case number and percentage. Analysis of variance was used to compare the four groups of myopic patients and was also used to compare the myopic and early-glaucoma groups. The least significant difference method was used to compare any two groups. The Chi-square test was used to compare the color code of the myopic groups. After drawing the ROC curve, the area under the ROC curve (AUC) was calculated to distinguish between myopic and glaucomatous eyes to find the best single parameter of interest. RESULTS General condition In this study, a total of 248 patients (248 eyes) were selected, including 51 cases of early POAG, 79 control eyes (0.50 D to -0.50 D, excluding -0.50 D), 47 cases of low myopia (−0.50 to −3.00 D, excluding −3.00 D), 43 cases of moderate myopia (−3.00 to −6.00 D, excluding −6.00 D), and 28 cases of high myopia (≤−6.00 D). The demographics of all groups are shown in Table 1. The differences in diopters among all groups were statistically significant (P < 0.05). Table 1 Demographics of all groups Characteristics Early POAG (n = 51) Low myopia (n = 47) Moderate myopia (n = 43) High myopia (n = 28) Control (n = 79) Age (years) 57.65 ± 12.27* 33.77 ± 10.64 32.81 ± 9.66 32.11 ± 7.32 39.94 ± 12.49 Equivalent spherical −1.41 ± 1.97 2.12 ± 1.31 4.47 ± 0.82 7.54 ± 1.83 / Sex, n (%)  Male 27 (52.9) 18 (38.3) 11 (25.6) 12 (42.9) 37 (46.8)  Female 24 (47.1) 29 (61.7) 32 (74.4) 16 (57.1) 42 (53.2) Axial length (mm) 24.27 ± 1.41 23.90 ± 0.67 25.09 ± 0.89 26.68 ± 1.06 23.03 ± 0.73 BCVA 0.95 ± 0.15 1.15 ± 0.12 1.12 ± 0.06 1.11 ± 0.09 1.18 ± 0.14 MD −2.899 ± 1.780 −0.78 ± 1.01 −0.48 ± 1.20 −0.85 ± 1.46 −0.68 ± 1.10 PSD 3.68 ± 1.90 1.29 ± 0.71 1.32 ± 0.51 1.89 ± 1.22 1.69 ± 0.60 C/D 0.842 ± 0.120 0.252 ± 0.194 0.242 ± 0.187 0.270 ± 0.189 0.286 ± 0.189 Data are presented as mean ± SD. *The difference between glaucoma and other groups was statistically significant. POAG: Primary open-angle glaucoma; BCVA: Best-corrected visual acuity; C/D: Cup-to-disc ratio; MD: Mean deviation; PSD: Pattern standard deviation; /: Not available. Spectral domain-optical coherence tomography parameters The mean and standard deviation of SD-OCT parameters in early POAG patients and each myopic group are shown in Table 2. Table 2 also shows the results of comparisons between the control group and other groups. The temporal RNFL thickness was thicker for the high-myopic group than for the early POAG group (P < 0.05), while the other quadrant RNFL thicknesses were thinner for the high-myopic group. Table 2 SD-OCT parameters in early POAG, control, and each group of myopic patients (mean ± SD) Parameters Early POAG (n = 51) Control (n = 79) Low myopia (n = 47) Moderate myopia (n = 43) High myopia (n = 28) F P RNFL average 85.172 ± 12.099 112.871 ± 10.886 112.594 ± 14.087† 104.922 ± 10.262*,† 99.750 ± 8.469*,† 53.630 <0.001 SH 87.645 ± 15.538 111.177 ± 12.542 112.633 ± 15.079† 110.326 ± 13.508† 104.333 ± 10.662† 29.654 <0.001 IH 82.695 ± 12.761 115.154 ± 12.632 111.013 ± 13.855† 99.530 ± 11.653*,† 95.442 ± 10.934*,† 59.905 <0.001 TL2 67.647 ± 13.688 88.520 ± 18.060 92.901 ± 22.619† 102.380 ± 23.150*,† 94.224 ± 17.052† 22.090 <0.001 TL1 53.588 ± 10.074 65.414 ± 9.594 69.144 ± 12.665† 73.111 ± 14.402*,† 69.385 ± 15.153† 18.948 <0.001 TU1 58.961 ± 12.159 73.881 ± 12.637 78.642 ± 20.340† 80.015 ± 14.312† 73.826 ± 13.538† 15.911 <0.001 TU2 76.961 ± 19.187 103.330 ± 20.424 109.860 ± 20.844† 113.130 ± 24.813† 104.780 ± 20.308† 22.697 <0.001 ST2 100.920 ± 29.417 141.880 ± 25.548 148.710 ± 23.327† 146.460 ± 20.819† 136.610 ± 21.307† 31.465 <0.001 ST1 113.590 ± 30.473 152.930 ± 24.355 147.400 ± 26.964† 135.300 ± 31.144*,† 126.650 ± 21.131* 19.030 <0.001 SN1 103.160 ± 23.582 132.560 ± 25.413 128.190 ± 21.261† 120.030 ± 26.724*,† 118.220 ± 20.542*,† 12.677 <0.001 SN2 102.920 ± 18.984 130.900 ± 24.290 126.210 ± 20.755† 112.180 ± 21.824*,† 110.970 ± 13.854* 17.051 <0.001 NU2 84.039 ± 19.106 102.590 ± 18.380 95.893 ± 15.926*,† 81.061 ± 18.693*,† 80.213 ± 13.822*,† 17.323 <0.001 NU1 60.490 ± 12.732 72.206 ± 11.856 65.141 ± 11.811* 57.753 ± 12.369* 57.530 ± 9.858* 15.547 <0.001 NL1 56.726 ± 9.877 66.293 ± 9.945 60.669 ± 11.996* 55.059 ± 8.709* 53.861 ± 8.590* 14.443 <0.001 NL2 73.490 ± 14.202 87.500 ± 15.510 81.241 ± 17.239*,† 72.933 ± 13.571* 71.453 ± 12.310* 11.925 <0.001 IN2 101.100 ± 18.790 126.630 ± 18.669 121.340 ± 20.956† 105.890 ± 17.005* 102.580 ± 12.948* 22.384 <0.001 IN1 104.710 ± 21.569 150.550 ± 28.555 145.740 ± 28.744† 122.410 ± 24.160*,† 117.330 ± 23.039*,† 31.165 <0.001 IT1 109.800 ± 28.702 170.900 ± 22.725 170.010 ± 28.783† 150.510 ± 26.946*,† 142.140 ± 26.628*,† 49.176 <0.001 IT2 94.314 ± 25.464 144.560 ± 27.828 148.060 ± 29.029† 150.620 ± 29.660† 138.430 ± 24.660† 36.287 <0.001 GCC-a 80.717 ± 8.727 96.801 ± 5.868 95.952 ± 13.815† 93.724 ± 6.025† 90.869 ± 5.835*,† 31.569 <0.001 GCC-S 84.471 ± 10.034 96.626 ± 5.783 96.377 ± 14.446† 93.889 ± 6.384† 91.627 ± 5.729*,† 16.446 <0.001 GCC-I 76.960 ± 11.877 96.998 ± 6.463 95.531 ± 13.429† 93.657 ± 6.149*,† 90.105 ± 6.502*,† 40.350 <0.001 I 102.480 ± 19.113 148.160 ± 17.627 146.290 ± 19.466† 132.360 ± 18.183*,† 125.120 ± 17.047*,† 56.325 <0.001 S 105.150 ± 21.280 139.570 ± 19.291 137.630 ± 18.758† 128.490 ± 20.637*,† 123.110 ± 13.582*,† 28.265 <0.001 N 68.686 ± 12.524 82.148 ± 12.379 75.736 ± 12.846*,† 66.702 ± 12.163* 65.764 ± 10.052* 18.366 <0.001 T 64.289 ± 11.375 82.787 ± 13.017 87.637 ± 16.396† 92.160 ± 17.450*,† 85.554 ± 13.616† 27.209 <0.001 IT 102.060 ± 25.213 157.730 ± 21.776 159.040 ± 23.899† 150.560 ± 24.732† 140.290 ± 22.088*,† 53.239 <0.001 IN 102.900 ± 18.854 138.590 ± 22.007 133.540 ± 22.057† 114.150 ± 19.681*,† 109.950 ± 16.565* 31.779 <0.001 NL 65.108 ± 11.506 76.897 ± 12.234 70.955 ± 14.161*,† 63.996 ± 10.756*,† 62.657 ± 10.074*,† 13.873 <0.001 NU 72.265 ± 15.246 87.399 ± 14.422 80.517 ± 13.108*,† 69.407 ± 15.073*,† 68.871 ± 11.332*,† 18.003 <0.001 SN 103.040 ± 20.005 131.730 ± 23.914 127.200 ± 19.376† 116.110 ± 22.948*,† 114.600 ± 15.424*,† 16.187 <0.001 ST 107.250 ± 27.967 147.400 ± 19.981 148.060 ± 22.210† 140.880 ± 21.866† 131.630 ± 16.734*,† 30.615 <0.001 TU 67.961 ± 14.866 88.607 ± 15.886 94.253 ± 19.957† 96.573 ± 18.723*,† 89.303 ± 16.006† 21.697 <0.001 TL 60.618 ± 11.147 76.967 ± 13.088 81.022 ± 16.403† 87.747 ± 18.003*,† 81.804 ± 15.047† 23.570 <0.001 *The difference between the control and myopic groups was statistically significant, P<0.05; †The difference between the early-glaucoma and myopic groups was statistically significant, P<0.05. RNFL: Retinal nerve fiber layer; SD-OCT: Spectral domain-optical coherence tomography; POAG: Primary open-angle glaucoma; SD: Standard deviation; GCC: Ganglion cell complex. Receiver operating characteristic curves We used a logistic regression model to correct for age, given the older ages of the glaucoma group patients (P < 0.05). P < 0.05 indicated statistical difference and that the parameter was capable of distinguishing glaucoma in myopic patients. We excluded 18 parameters (IH, TL1, ST1, I, N, IT1, IN, IN1, IN2, NL, NL1, NL2, NU, NU1, NU2, SN, SN1, and SN2) in the high-myopic group and 13 parameters (IN, IN1, IN2, NL, NL1, NL2, NU, NU1, NU2, SN, SN1, SN2, and N) in the moderate-myopic group according to logistic regression results [Table 3]. ROC curves for parameters with significant differences were constructed and the AUCs were calculated [Table 4]. Table 3 P values of the logistic regression model Parameters Early POAG versus control Early POAG versus low myopia Early POAG versus moderate myopia Early POAG versus high myopia Wald P Wald P Wald P Wald P RNFL average 11.015 0.001 28.966 <0.001 12.040 0.001 6.744 0.009 SH 24.581 <0.001 26.254 <0.001 12.727 0.000 7.596 0.006 IH 19.277 <0.001 28.473 <0.001 6.725 0.009 3.712 0.054 TL2 14.542 <0.001 16.640 <0.001 12.463 0.000 6.673 0.010 TL1 16.892 <0.001 18.546 <0.001 9.779 0.002 2.566 0.109 TU1 19.583 <0.001 21.883 <0.001 11.943 0.001 6.970 0.08 TU2 19.653 <0.001 23.235 <0.001 12.592 0.000 8.923 0.003 ST2 21.772 <0.001 25.778 <0.001 13.059 0.000 8.257 0.004 ST1 22.310 <0.001 27.150 <0.001 6.072 0.014 3.620 0.057 SN1 20.659 <0.001 23.669 <0.001 3.168 0.075 3.478 0.062 SN2 19.407 <0.001 22.034 <0.001 1.401 0.236 1.294 0.255 NU2 16.786 <0.001 16.337 <0.001 0.002 0.962 0.414 0.520 NU1 13.997 <0.001 14.687 <0.001 0.040 0.842 0.165 0.685 NL1 16.871 <0.001 17.211 <0.001 0.075 0.784 0.486 0.486 NL2 14.996 <0.001 16.099 <0.001 0.360 0.549 0.166 0.684 IN2 21.907 <0.001 23.130 <0.001 0.039 0.843 0.008 0.927 IN1 26.911 <0.001 30.110 <0.001 1.071 0.301 0.032 0.859 IT1 23.962 <0.001 27.696 <0.001 5.570 0.018 1.685 0.194 IT2 24.812 <0.001 26.618 <0.001 12.885 0.000 6.781 0.009 GCC-a 20.383 <0.001 26.669 <0.001 11.687 0.001 7.506 0.006 GCC-S 19.987 <0.001 25.539 <0.001 11.055 0.001 7.933 0.005 GCC-I 20.455 <0.001 26.467 <0.001 11.727 0.001 6.986 0.008 I 21.473 <0.001 27.633 <0.001 7.456 0.006 2.664 0.103 S 24.721 <0.001 26.438 <0.001 9.730 0.002 6.474 0.011 N 17.907 <0.001 18.818 <0.001 0.069 0.793 0.340 0.560 T 20.790 <0.001 24.376 <0.001 12.310 0.000 7.741 0.005 IT 22.803 <0.001 27.897 <0.001 10.437 0.001 4.766 0.029 IN 26.534 <0.001 29.521 <0.001 0.522 0.470 0.024 0.878 NL 16.665 <0.001 17.556 <0.001 0.237 0.626 0.292 0.589 NU 16.149 <0.001 16.606 <0.001 0.003 0.954 0.320 0.571 SN 22.244 <0.001 23.659 <0.001 2.619 0.106 2.725 0.099 ST 24.435 <0.001 25.991 <0.001 12.063 0.001 8.007 0.005 TU 19.888 <0.001 24.318 <0.001 12.012 0.001 8.777 0.003 TL 16.928 <0.001 18.282 <0.001 11.842 0.001 5.296 0.021 POAG: Primary open-angle glaucoma; RNFL: Retinal nerve fiber layer; GCC: Ganglion cell complex. Table 4 AUC of all parameters AUC Early POAG versus control Early POAG versus low myopia Early POAG versus moderate myopia Early POAG versus high myopia >0.900 IH, I, IT, IT1, RNFL average, GCC-a, GCC-I, IN1 I, IH, IT, IT1, RNFL average, GCC-a, GCC-I, IT2 TL2, IT2, T, TL, IT >0.800–0.900 IT2, IN, S, SH, ST, GCC-S, T, IN2, ST2, ST1, SN, SN2, TL2, TL, TU2, TU, SN1, TU1 IN1, S, SH, IN, ST, T, ST2, TU2, TU, GCC-S, TL, TL2, SN, ST1, TU1, SN2, TL1, IN2, SN1 RNFL average, GCC-a, TU, TL1, TU2, ST2, GCC-I, TU1, SH, I, IT1, IH, ST, GCC-S, S TL2, T, TL, IT2, IT, RNFL average, TU2, TU, ST2, GCC-I, GCC-a, SH, TU1 0.700–0.800 TL1, N, NU2, NU, NL, NL2, NU1, NL1 NU2, N, NU, NL, NL2, NU1 ST, S, GCC-S <0.700 NL1 ST1 AUC: Area under the curve; POAG: Primary open-angle glaucoma; RNFL: Retinal nerve fiber layer; GCC: Ganglion cell complex. We further analyzed the parameters of the inferior, superior, inferior temporal, and superior temporal quadrants, which had all been well documented for their effectiveness in the diagnosis of glaucoma [Figures 2–5]. The results are shown in Table 5, when the specificity was calculated at a sensitivity of 85%. Figure 2 ROC of early POAG versus control. ROC: Receiver operating characteristic; POAG: Primary open-angle glaucoma. Figure 3 ROC of early POAG versus low myopia. ROC: Receiver operating characteristic; POAG: Primary open-angle glaucoma. Figure 4 ROC of early POAG versus moderate myopia. ROC: Receiver operating characteristic; POAG: Primary open-angle glaucoma. Figure 5 ROC of early POAG versus high myopia. ROC: Receiver operating characteristic; POAG: Primary open-angle glaucoma. Table 5 AUC and specificity when the sensitivity was 85% Parameters Early POAG versus control Early POAG versus low myopia Early POAG versus moderate myopia Early POAG versus high myopia AUC Specificity (%) AUC Specificity (%) AUC Specificity (%) AUC Specificity (%) RNFL average 0.940 89.90 0.932 89.40 0.890 76.70 0.850 64.30 SH 0.874 75.90 0.877 80.90 0.869 79.10 0.818 67.90 IH 0.962 96.20 0.947 83.00 0.836 58.10 / / I 0.958 94.90 0.948 89.40 0.864 67.40 / / S 0.886 73.40 0.880 72.30 0.802 46.50 0.758 28.60 IT 0.944 84.80 0.942 89.40 0.906 79.10 0.861 57.10 ST 0.870 68.40 0.868 63.80 0.817 48.80 0.761 28.60 GCC-S 0.859 70.90 0.839 61.70 0.802 60.50 0.731 42.90 GCC-I 0.932 79.70 0.916 66.00 0.880 62.80 0.825 35.70 GCC-a 0.939 86.10 0.921 76.60 0.889 74.40 0.822 53.60 AUC: Area under the curve; POAG: Primary open-angle glaucoma; RNFL: Retinal nerve fiber layer; GCC: Ganglion cell complex; /: Not available. Color code The color code provided by SD-OCT is shown in Table 6. The number of parameters judged as normal (green) was determined from SD-OCT results. Parameters recognized for their effectiveness in the diagnosis of glaucoma were calculated. Table 7 shows the results of the Chi-square test. The differences of most parameters between the high-myopic group and other groups were significant (P < 0.05). Some parameters of the moderate-myopic group compared with the other groups were also statistically significant (P < 0.05). Table 6 Numbers of green colors from SD-OCT, n (%) Parameters High myopia (n = 28) Moderate myopia (n = 43) Low myopia (n = 47) Control (n = 79) RNFL average 12 (42.9) 31 (72.1) 42 (89.4) 62 (78.5) Superior 15 (53.6) 31 (72.1) 44 (93.6) 63 (79.7) Inferior 13 (46.4) 31 (72.1) 42 (89.4) 70 (88.6) ST1 17 (60.7) 34 (79.1) 45 (95.7) 74 (93.7) ST2 20 (71.4) 39 (90.7) 45 (97.9) 63 (79.7) IT1 12 (42.9) 29 (67.4) 45 (95.7) 72 (91.1) IT2 20 (71.4) 39 (90.7) 39 (83.0) 68 (86.1) SD-OCT: Spectral domain-optical coherence tomography; RNFL: Retinal nerve fiber layer. Table 7 P values from the Chi-square test of the green color code between myopic groups Parameters HM versus MM HM versus LM HM versus control MM versus LM MM versus control LM versus control χ2 P χ2 P χ2 P χ2 P χ2 P χ2 P RNFL average 6.069 0.013 18.823 <0.001 12.300 0.001 4.371 0.034 0.627 0.282 2.421 0.092 Superior 20550 0.090 16.767 <0.001 7.169 0.009 7.490 0.006 0.922 0.230 4.427 0.028 Inferior 4.739 0.027 16.539 <0.001 21.138 <0.001 4.371 0.034 5.329 0.021 0.017 0.572 ST1 2.824 0.080 15.027 <0.001 17.656 <0.001 5.820 0.017 5.844 0.019 0.242 0.478 ST2 4.483 0.038 11.619 0.001 0.822 0.256 2.203 0.154 2.436 0.093 8.295 0.002 IT1 4.201 0.036 26.908 <0.001 28.558 <0.001 12.306 <0.001 10.973 0.001 0.942 0.277 IT2 4.483 0.040 1.395 0.186 3.037 0.080 1.158 0.220 0.552 0.332 0.221 0.410 HM: High myopia; MM: Moderate myopia; LM: Low myopia; RNFL: Retinal nerve fiber layer. DISCUSSION With the increase in cases of myopia,[1] the early diagnosis of POAG in myopia becomes especially important. Changes in the myopic fundus, such as disc rotation, distortion, and deformation,[12] affect the observations of shape and size of the optic cup and disc and interfere with the qualitative analysis of glaucoma in myopia and the accuracy of quantitative examinations. In the present study, myopia affected the distribution of the RNFL thicknesses around the optic disc, and the mean, inferior, and superior quadrants of the RNFL were thinner than that of the normal control eyes. In contrast, the temporal RNFL was thicker. These findings were consistent with those from previous studies.[3] These changes caused the reliability of OCT, Heidelberg retinal tomography, and polarized laser scanner parameters to be worse than that of nonmyopic eyes, especially for high-myopic patients.[34] In recent years, clinical applications involving quantitative analysis of glaucoma are becoming increasingly common. If the accuracy of the measured results is poor, the percentages of misdiagnoses will increase.[56] In the present study, we used SD-OCT, which is widely used in the early diagnosis of glaucoma. Based on previous reports, the diagnostic ability using CIRRUS, RTVUE, or three-dimensional OCT for patients with both POAG and myopia was comparable.[7891011] The parameters of RNFL thickness and GCC have a high diagnostic performance for POAG with high-myopic patients, compared with nonglaucomatous high-myopic patients, including preperimetric POAG patients.[12] However, for most myopic patients without POAG, numerous studies have reported that the RNFL was also abnormally thin due to axial extension and atrophy of the retina.[256] In our study, a thinner RNFL was found in all myopic groups, especially for the moderate- and high-myopic groups. In the high-myopic group, the thinning included almost all the observational parameters. The main pathological change of glaucoma is selective loss of retinal ganglion cells causing thinning of the RNFL.[1314] Both glaucoma and myopic patients have similar OCT results due to RNFL thinning.[2] This process makes myopia easily misdiagnosed as glaucoma, especially high myopia. Based on the AUC values in our study, when the AUC was >0.900, the number of parameters of the control and low-myopic groups was 8/34 and 5/34, respectively, whereas that of moderate-myopic group was 5/34 and the high-myopic group was 0. In contrast, when the AUC was <0.700, the number of parameters of the control and low-myopic groups was 0 and 1, respectively, and that of the moderate- and high-myopic groups was the same. These results indicated that the diagnostic efficacies of OCT for moderate and high myopia were reduced. The main purpose of this study was to evaluate the ability of OCT to distinguish between myopia and early POAG. We therefore emphasized the diagnostic specificity of the SD-OCT parameters, which were well in distinguishing between normal and POAG in previous studies. When the sensitivity was 85%, specificity results indicated that most parameters of the control and low-myopic groups were better than those of the moderate- and high-myopic groups. The specificity of patients in the high-myopic group was <70%, or sometimes <50%, indicating that it was easy to be misdiagnosed with myopia when SD-OCT was used, especially for high-myopic patients. According to the internal normative database of OCT, the printing results showed a color code for each parameter to determine the outcomes using three colors (green, normal; yellow, critical; and red, abnormal). We calculated the number of parameters that were judged as normal (green), which were significantly lower in the moderate- and high-myopic groups. Almost 40% of the high-myopic patients were judged as critical or abnormal according to the RNFL average. At present, there have been few studies in this field. Kim et al. reported that although OCT has a higher sensitivity in high-myopic patients with glaucoma, it also has a lower specificity.[4] Akashi et al.[3] studied three types of OCT diagnostic efficacies for high-myopic patients with glaucoma, reporting that the results were different, regardless of whether the normal control group had a high myopia. Considering these previous results and the well-known observation that analyses using OCT can many times lead to misdiagnosis by ophthalmologists, we suggest that a normative database of various diopters (especially high myopia) should be established for diagnoses using OCT. Many previous investigators have suggested a similar view that this database will improve glaucoma diagnosis of myopic patients and reduce the percentage of misdiagnoses.[234] Our study had several limitations. First, this study focused on the specificity index, although there was insufficient grouping (glaucoma with high-myopic group) to support the sensitivity observations. Second, the age of patients in the early-glaucoma group was significantly older than that of other groups. Since the RNFL thickness decreases with age,[15] we used a logistic regression model to correct age differences, which could affect the results. In the future, prospective studies with age-matched participants should result in more definitive conclusions. In summary, the glaucoma diagnostic parameters of SD-OCT were not clinically relevant for moderate- and high-myopic patients. The specificities were low. As a result, misdiagnosis as glaucoma is more likely to occur in moderate- and high-myopic patients. Multifactorial analyses should be used in the diagnoses of glaucoma in moderate- and high-myopic patients. It is also suggested that the population-averaged OCT database of various diopters (especially high myopia) should be established for diagnoses using OCT. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. 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