April 2012
Volume 53, Issue 4
Free
Glaucoma  |   April 2012
Glaucoma Diagnostic Ability of Quadrant and Clock-Hour Neuroretinal Rim Assessment Using Cirrus HD Optical Coherence Tomography
Author Affiliations & Notes
  • Young Hoon Hwang
    From the 1Department of Ophthalmology, Konyang University, Kim's Eye Hospital, Myung-Gok Eye Research Institute, Seoul, Korea; Department of Ophthalmology, Armed Forces Capital Hospital, Seongnam, Korea; and Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea.
  • Yong Yeon Kim
    From the 1Department of Ophthalmology, Konyang University, Kim's Eye Hospital, Myung-Gok Eye Research Institute, Seoul, Korea; Department of Ophthalmology, Armed Forces Capital Hospital, Seongnam, Korea; and Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea.
  • Corresponding author: Yong Yeon Kim, Department of Ophthalmology, Korea University Guro Hospital, #97 Gurodonggil, Guro-gu, Seoul 152–703, Republic of Korea; [email protected]
Investigative Ophthalmology & Visual Science April 2012, Vol.53, 2226-2234. doi:https://doi.org/10.1167/iovs.11-8689
  • Views
  • PDF
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Young Hoon Hwang, Yong Yeon Kim; Glaucoma Diagnostic Ability of Quadrant and Clock-Hour Neuroretinal Rim Assessment Using Cirrus HD Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2012;53(4):2226-2234. https://doi.org/10.1167/iovs.11-8689.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract

Purpose: The aim of this study was to investigate the glaucoma diagnostic ability of quadrant and clock-hour neuroretinal rim assessment by Cirrus HD spectral-domain optical coherence tomography (OCT).

Methods: Eighty eyes of 80 glaucoma patients and 80 eyes of 80 healthy subjects were enrolled. Peripapillary retinal nerve fiber layer (RNFL) thickness was measured by Cirrus HD-OCT. Quadrant and clock-hour rim areas and thicknesses were obtained from optic nerve head images and 360° circumferential rim thickness curve of Cirrus HD-OCT, respectively. Area under receiver operating characteristic curves (AUCs) and sensitivities of RNFL thicknesses, rim areas, and rim thicknesses at a 90% specificity level were calculated.

Results: Quadrant and clock-hour rim area and thickness showed good diagnostic ability for glaucoma in all areas (AUCs, 0.877–0.969; sensitivities, 67.5%–96.3%). When the AUCs of RNFL thicknesses, rim areas, and rim thicknesses were compared, no significant difference was found in global area and superior and inferior quadrants (P > 0.05). However, in nasal and temporal quadrants, rim area and thickness had greater AUCs (AUCs, 0.919–0.945; sensitivities, 82.5%–86.3%) than RNFL thickness (AUCs, 0.749–0.776; sensitivities, 12.5%–33.8%; P < 0.001). Eyes with moderate to advanced glaucoma (mean deviation < −6 dB) had thinner RNFL than mild glaucoma (mean deviation ≥ −6 dB) in global area, superior, inferior, and temporal quadrants (P < 0.003); rim area and thickness showed no significant difference in all areas (P > 0.003).

Conclusions: Neuroretinal rim assessment in nasal and temporal areas by Cirrus HD-OCT may enhance glaucoma diagnostic ability. RNFL and rim changes measured by Cirrus HD-OCT may be different according to the stages of glaucomatous damage.

Introduction
Optical coherence tomography (OCT) is a widely used device for the evaluation of peripapillary retinal nerve fiber layer (RNFL) in eyes with glaucoma. 1,2 Recent studies have also reported that neuroretinal rim measurements by spectral-domain OCT are excellent with respect to reproducibility, glaucoma diagnostic ability, and low rate of incorrect optic disc margin detection. 35 However, only average rim areas have been assessed in previous studies, 35 with little knowledge gained concerning the glaucoma diagnostic ability of sectorial (quadrant and clock-hour) neuroretinal rim assessment as determined by OCT. 
Neuroretinal rim change can be diffuse or localized in eyes with glaucoma, 68 and rim notching can coexist with a diffuse thinning of the rim or may develop independently. 9 Therefore, the evaluation of not only global rim, but also quadrant and clock-hour rim may enhance the glaucoma diagnostic ability of neuroretinal rim assessment. A study using the HRT confocal scanning laser ophthalmoscopy (Heidelberg Engineering, GmbH, Dossenheim, Germany) reported that sectorial analysis of the optic nerve head (ONH) may offer a potential advantage over global ONH analysis in glaucoma evaluation. 9  
ONH analysis algorithm with Cirrus HD spectral-domain OCT (Cirrus HD-OCT; Carl Zeiss Meditec, Dublin, CA) automatically identifies the borders of optic discs and cups. Cirrus HD-OCT software provides rim area (area between the optic disc margin and cup area) in the en face ONH OCT image. Neuroretinal rim thicknesses, defined as the distance between the optic disc margin and cup margin at a specific point, in a 360° circumferential area are presented as a neuroretinal rim thickness curve with Cirrus HD-OCT. 3 Therefore, quadrant and clock-hour rim areas and thicknesses can be assessed by analyzing the en face ONH images and the neuroretinal rim thickness curve provided with Cirrus HD-OCT. 
This study was performed to evaluate the glaucoma diagnostic ability of quadrant and clock-hour neuroretinal rim area and thickness assessment using Cirrus HD-OCT. 
Methods
Participants
The study protocol was approved by the Institutional Review Board of the Armed Forces Capital Hospital, Seongnam, Korea. All participants provided informed consent prior to enrollment, and all procedures conformed to the guidelines of the Declaration of Helsinki. Participants were recruited consecutively between May 2009 and September 2011 at the glaucoma clinic of the Armed Forces Capital Hospital. 
Each subject underwent a full ophthalmic examination, including assessments of visual acuity, refractive error with a model RK-F1 autorefractor keratometer (Canon, Tokyo, Japan), and intraocular pressure (IOP) with a Goldmann applanation tonometer; anterior segment examination by slit-lamp biomicroscopy; axial length (AL) measurement by a HiScan A-scan (Optikon, Rome, Italy); ONH evaluation and fundus examination with a 90 diopter (D) lens; 30-2 Swedish Interactive Threshold Algorithm standard automated visual field (VF) test using a Humphrey Visual Field Analyzer (Carl Zeiss Meditec); red-free fundus photograph using a Zeiss FF450 fundus camera (Carl Zeiss Meditec); and peripapillary RNFL and ONH measurement using the Cirrus HD-OCT. Previous studies have reported a significant association between refractive error and OCT measurements. 10,11 Thus, to minimize the effect of refractive error on OCT measurements, only eyes with a spherical equivalent (SE; spherical refractive error + ½ cylindrical refractive error in the negative form) ≤ ±2.00 D were included. Only the right eye of each subject was enrolled. 
Inclusion criteria for glaucoma patients were best corrected visual acuity of 20/30 or better; normal anterior segment on slit-lamp examination; open angle on gonioscopic examination; ONH with glaucomatous changes (i.e., increased cup–disc ratio and narrowing of the neuroretinal rim); RNFL defect on red-free fundus photography (i.e., a dark wedge-shaped area with its apex touching the optic disc border in the brightly striated pattern of the surrounding RNFL 12 or generalized loss of RNFL visibility in the upper or lower retina13); and glaucomatous VF defects (i.e., a cluster of three points with probabilities of <5% on the pattern deviation map in at least one hemifield, including at least one point with a probability of <1%, or a cluster of two points with a probability of <1%) and glaucomatous hemifield test results outside normal limits, or a pattern standard deviation beyond 95% of normal limits 14 as confirmed by at least two reliable examinations (false positives and negatives <15%, fixation losses <15%). Exclusion criteria were spherical equivalent ≥ ±2.0 D; history of ocular inflammation, trauma, or prior glaucoma treatment including ocular surgery or laser; and presence of concurrent retinal disease (i.e., vascular disorder, macular degeneration), optic nerve disease other than glaucoma, or brain disorder that could influence VF results. 
During the study period, 312 glaucoma patients visited our clinic. Among them, 234 glaucoma patients met the inclusion criteria and the patients were classified into mild (mean deviation ≥ −6 dB, n = 164) and moderate to advanced (mean deviation < −6 dB, n = 70) glaucoma groups according to the Hodapp–Parrish–Anderson criterion. 15 Forty patients were randomly selected from each group. 
Healthy subjects matched to patients based on age, SE, and optic disc size measured by Cirrus HD-OCT were recruited from our previous study population 11,16 as well as subjects who visited our clinic during the enrollment period for an annual health examination. Inclusion criteria for healthy subjects (control group) consisted of a best corrected visual acuity of 20/30 or better; normal IOP (≤21 mm Hg) as determined by a model CT-80 noncontact tonometer (Topcon, Tokyo, Japan); normal anterior chamber and open-angle, normal ONH without glaucomatous changes; no RNFL defect on red-free fundus photography; and normal reliable VF test results. 
OCT measurement
A 200 by 200 cube Optic Disc Scan was obtained using Cirrus HD-OCT as described previously. 11 For image acquisition, scanning laser images were focused after subjects were seated and properly positioned. Using the iris and fundus viewports, alignment was properly positioned to the ONH in the center of the scan. Once the ONH was centered on the live scanning laser image, a 6- by 6-mm square of data was captured. 
The built-in algorithms of Cirrus HD-OCT software (version 5.1.0.96) are capable of automatically identifying the vitreoretinal interface and posterior boundary of the RNFL and can subsequently calculate the average, superior, nasal, inferior, temporal, and 12 clock-hour RNFL thickness parameters. The algorithms can also be used to automatically identify optic disc margins at the termination of Bruch's membrane, whereby the rim width (rim thickness) around the entire circumference of the optic disc is then automatically determined by measuring the thickness of the neuroretinal tissue in the optic nerve as it turns to exit through the opening in Bruch's membrane. 3 Images with poor quality were excluded; poor quality images were those with signal strength ≤6, incorrect identification of the vitreoretinal surface detection algorithm in the peripapillary RNFL extracted B-scan, misidentification of Bruch's membrane termination in the horizontal and vertical optic nerve extracted B-scans, and prominent involuntary saccade during the scan. 5  
The ONH en face image with optic disc margin (black circle in Fig. 1), cup margin (red circle in Fig. 1), and rim area (area between disc margin and cup margin) were presented in RNFL deviation maps without user interaction involvement. After saving the ONH en face image as a picture file, clock-hour rim areas were measured with National Institutes of Health ImageJ 1.42q image analysis software as presented in Figure 1
Figure 1.
 
An example of quadrant and clock-hour neuroretinal rim area and thickness and RNFL thickness measured by Cirrus HD-OCT in an eye with glaucoma. Rim area was determined as the area between the optic disc margin (black circle) and cup margin (red circle); neuroretinal rim thickness was defined as the distance between optic disc margin and cup margin at a specific point.
Figure 1.
 
An example of quadrant and clock-hour neuroretinal rim area and thickness and RNFL thickness measured by Cirrus HD-OCT in an eye with glaucoma. Rim area was determined as the area between the optic disc margin (black circle) and cup margin (red circle); neuroretinal rim thickness was defined as the distance between optic disc margin and cup margin at a specific point.
The following equations were introduced to adjust the magnification difference between rim area measured by ImageJ and the rim area determined by Cirrus HD-OCT; adjusted rim area was used for the statistical analysis.     
By using the ONH and RNFL thickness analysis mode of Cirrus HD-OCT, rim thickness at each point (range, 1–360; 360 means the 9 clock-hour position and 180 means the 3 clock-hour position) could be obtained at the 360° circumferential rim thickness curve by positioning the vertical measurement bar at each point as presented in Figure 1. Clock-hour rim thicknesses at each point (30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, and 360) were measured with the rim thickness curve of Cirrus HD-OCT (Fig. 1). Quadrant rim area and thickness were calculated by the average of clock-hour sector rim areas and thicknesses in corresponding areas, while the average rim area and thicknesses were obtained from the average of all quadrant areas and thicknesses. 
Statistical analyses
The distribution of all variables was examined for normality using the Kolmogorov-Smirnov one-sample test. Unpaired t-test, analysis of variance with Bonferroni post hoc analysis (for the variables with normal distribution) or Kruskal-Wallis tests (for the variables without normal distribution) were performed to compare clinical characteristics, rim characteristics, and RNFL thickness among the control, mild glaucoma, and moderate to advanced glaucoma groups. The relative amount of RNFL and rim loss in the glaucoma group compared with the control group was calculated using the following equation17:    
To evaluate the diagnostic ability for glaucoma of average, quadrant, and clock-hour rim areas, as well as rim thickness and RNFL thickness, areas under the receiver operating characteristics curves (AUCs) were calculated and compared. Sensitivities at a fixed specificity of 90% were calculated from the receiver operating characteristics curves. For this study, the AUC was classified as follows: 0.9 to 1.0 = excellent, 0.80 to 0.89 = good, 0.70 to 0.79 = fair, 0.60 to 0.69 = poor, and 0.50 to 0.59 = worthless. 18 Significant differences between AUCs were assessed as described previously. 19 For the RNFL thickness, rim area, and rim thickness comparisons, Bonferroni adjustments were made based on the number of comparisons. For the other analyses, P < 0.05 was considered statistically significant. Statistical analyses were performed using SPSS version 12.0 (SPSS, Chicago, IL) and MedCalc version 11.6.1.0 (MedCalc Software bvba, Mariakerke, Belgium). 
Results
Eighty right eyes of 80 glaucoma patients (40 mild glaucoma patients and 40 moderate to advanced glaucoma patients) and 80 right eyes of 80 healthy subjects were enrolled. All participants were Korean males. Their clinical characteristics are summarized in Table 1. When the clinical characteristics of the control, mild, and moderate to advanced glaucoma groups were compared, significant differences were found in IOP and VF indices (P values < 0.001, except for the IOP difference between the control and mild glaucoma groups). Other characteristics, including age, SE, AL, and optic disc size were not significantly different among the groups (P values > 0.05, Table 1). Among the patients in the glaucoma group, 80% of those with mild glaucoma (32 out of 40) and 60% of those with moderate to advanced glaucoma (24 out of 40) had pretreatment IOP ≤ 21 mm Hg. 
Table 1.
 
Clinical Characteristics of the Control and Glaucoma Groups (Mean ± Standard Deviation)
Table 1.
 
Clinical Characteristics of the Control and Glaucoma Groups (Mean ± Standard Deviation)
Control (n = 80) Glaucoma P1 P2 P3
All (n = 80) Mild (n = 40) Moderate to Advanced (n = 40)
Age (years) 55.39 ± 11.15 53.94 ± 11.17 53.59 ± 11.87 54.29 ± 10.58 0.433* 1.000 1.000
IOP (mm Hg) 16.18 ± 2.21 18.62 ± 4.46 17.26 ± 2.60 19.97 ± 5.47 <0.001* 0.332 <0.001
SE (D) −0.99 ± 0.67 −0.97 ± 0.83 −1.06 ± 0.78 −0.88 ± 0.87 0.814* 1.000 0.911
Axial length (mm) 24.05 ± 0.72 24.12 ± 0.60 24.05 ± 0.37 24.18 ± 0.77 0.506* 1.000 0.937
Disc size (mm2) 2.12 ± 0.30 2.13 ± 0.40 2.19 ± 0.32 2.08 ± 0.46 0.857* 1.000 1.000
MD (dB) −0.43 ± 0.65 −6.90 ± 4.79 −3.33 ± 1.27 −10.47 ± 4.32 <0.001 <0.001 <0.001
PSD (dB) 1.01 ± 0.56 7.44 ± 3.73 4.39 ± 1.82 10.49 ± 2.42 <0.001 <0.001 <0.001
Data on the mean average, quadrant, and clock-hour RNFL thickness are presented in Table 2. After the Bonferroni adjustment (α = 0.003; 17 comparisons), all the glaucoma group patients had thinner RNFL than the control group in all areas (P values < 0.001) except for the 3 and 9 clock-hour sectors (P values > 0.003). When RNFL thicknesses of mild glaucoma and moderate to advanced glaucoma groups were compared, eyes in the moderate to advanced glaucoma group had thinner RNFL than those in the mild glaucoma group in global area and superior, inferior, and temporal quadrants (P values < 0.003) (Table 2). Data on neuroretinal rim area and thickness are provided in Tables 3 and 4, respectively. Eyes in the glaucoma group had less rim area or thinner rim than those in the control group in all areas (P values < 0.001). When rim area and thickness in the mild glaucoma group and moderate-to-advanced glaucoma group were compared, no significant differences were found (P values > 0.003, Tables 3 and 4). 
Table 2.
 
Retinal Nerve Fiber Layer Thickness (μm) in Average, Quadrant, and Clock-Hour Areas Measured by Cirrus HD-OCT (Mean ± Standard Deviation)
Table 2.
 
Retinal Nerve Fiber Layer Thickness (μm) in Average, Quadrant, and Clock-Hour Areas Measured by Cirrus HD-OCT (Mean ± Standard Deviation)
Control (n = 80) Glaucoma P1* P2† P3†
All (n = 80) Mild (n = 40) Moderate to Advanced (n = 40)
Average 97.75 ± 7.86 70.63 ± 11.55 75.29 ± 9.50 65.97 ± 11.65 <0.001 <0.001 <0.001
Quadrant
 Superior 127.69 ± 13.48 82.69 ± 19.66 88.44 ± 18.47 76.94 ± 19.38 <0.001 <0.001 <0.001
 Nasal 71.72 ± 8.99 62.34 ± 8.53 64.88 ± 8.13 59.79 ± 8.26 <0.001 <0.001 0.012
 Inferior 125.18 ± 13.37 81.18 ± 22.01 89.18 ± 18.99 73.18 ± 22.17 <0.001 <0.001 0.001
 Temporal 66.44 ± 6.78 56.84 ± 12.16 60.00 ± 11.59 53.68 ± 12.05 <0.001 0.003 <0.001
Clock-hour
 12 134.61 ± 23.61 83.85 ± 24.92 89.24 ± 22.15 78.47 ± 26.66 <0.001 <0.001 0.200
1 123.06 ± 20.53 80.37 ± 19.42 81.41 ± 19.31 79.32 ± 19.78 <0.001 <0.001 1.000
2 89.59 ± 14.96 69.66 ± 11.88 72.24 ± 12.16 67.09 ± 11.19 <0.001 <0.001 0.360
3 59.59 ± 8.58 58.56 ± 10.19 61.26 ± 8.87 55.85 ± 10.82 0.506 1.000 0.148
4 65.96 ± 12.13 58.57 ± 9.42 60.91 ± 9.65 56.24 ± 8.71 <0.001 0.075 0.236
5 100.69 ± 18.11 73.37 ± 15.95 79.15 ± 16.87 67.59 ± 12.78 <0.001 <0.001 0.015
6 138.11 ± 21.91 84.71 ± 28.52 95.26 ± 26.74 74.15 ± 26.57 <0.001 <0.001 0.001
7 136.21 ± 14.55 84.62 ± 34.86 91.91 ± 29.87 77.32 ± 38.72 <0.001 <0.001 0.059
8 68.76 ± 9.87 59.04 ± 15.92 63.12 ± 13.36 54.97 ± 17.36 <0.001 0.096 0.028
9 54.18 ± 7.69 50.53 ± 8.83 52.68 ± 8.10 48.38 ± 9.12 0.008 1.000 0.093
 10 76.53 ± 8.61 60.85 ± 17.05 64.06 ± 18.09 57.65 ± 15.55 <0.001 <0.001 0.133
 11 125.34 ± 15.62 82.65 ± 25.32 90.50 ± 27.13 74.79 ± 20.94 <0.001 <0.001 0.004
Table 3.
 
Neuroretinal Rim Area (mm2) in Average, Quadrant, and Clock-Hour Areas Measured by Cirrus HD-OCT (Mean ± Standard Deviation)
Table 3.
 
Neuroretinal Rim Area (mm2) in Average, Quadrant, and Clock-Hour Areas Measured by Cirrus HD-OCT (Mean ± Standard Deviation)
Control (n = 80) Glaucoma P1* P2† P3†
All (n = 80) Mild (n = 40) Moderate to Advanced (n = 40)
Average 1.29 ± 0.20 0.76 ± 0.20 0.81 ± 0.19 0.72 ± 0.21 <0.001 <0.001 0.170
Quadrant
 Superior 0.35 ± 0.06 0.21 ± 0.08 0.23 ± 0.10 0.20 ± 0.06 <0.001 <0.001 0.220
 Nasal 0.34 ± 0.07 0.21 ± 0.06 0.23 ± 0.06 0.20 ± 0.06 <0.001 <0.001 0.180
 Inferior 0.36 ± 0.07 0.21 ± 0.08 0.22 ± 0.07 0.20 ± 0.08 <0.001 <0.001 0.703
 Temporal 0.24 ± 0.05 0.13 ± 0.05 0.14 ± 0.04 0.13 ± 0.05 <0.001 <0.001 0.609
Clock-hour
 12 0.13 ± 0.02 0.08 ± 0.03 0.08 ± 0.04 0.07 ± 0.02 <0.001 <0.001 0.095
1 0.12 ± 0.02 0.08 ± 0.03 0.08 ± 0.03 0.07 ± 0.02 <0.001 <0.001 0.296
2 0.12 ± 0.02 0.07 ± 0.02 0.08 ± 0.02 0.07 ± 0.02 <0.001 <0.001 0.200
3 0.11 ± 0.02 0.07 ± 0.02 0.07 ± 0.02 0.06 ± 0.02 <0.001 <0.001 0.411
4 0.12 ± 0.08 0.07 ± 0.02 0.08 ± 0.02 0.07 ± 0.02 <0.001 <0.001 0.190
5 0.13 ± 0.03 0.08 ± 0.02 0.08 ± 0.02 0.07 ± 0.02 <0.001 <0.001 0.217
6 0.13 ± 0.03 0.07 ± 0.04 0.07 ± 0.03 0.07 ± 0.04 <0.001 <0.001 1.000
7 0.11 ± 0.02 0.06 ± 0.03 0.06 ± 0.02 0.05 ± 0.03 <0.001 <0.001 0.802
8 0.08 ± 0.05 0.05 ± 0.02 0.05 ± 0.01 0.04 ± 0.02 <0.001 <0.001 0.186
9 0.07 ± 0.05 0.04 ± 0.02 0.04 ± 0.01 0.04 ± 0.02 <0.001 <0.001 0.438
 10 0.08 ± 0.05 0.04 ± 0.02 0.05 ± 0.02 0.04 ± 0.02 <0.001 <0.001 1.000
 11 0.10 ± 0.06 0.06 ± 0.03 0.06 ± 0.03 0.05 ± 0.02 <0.001 <0.001 1.000
Table 4.
 
Neuroretinal Rim Thickness (μm) in Average, Quadrant, and Clock-Hour Areas Measured by Cirrus HD-OCT (Mean ± Standard Deviation)
Table 4.
 
Neuroretinal Rim Thickness (μm) in Average, Quadrant, and Clock-Hour Areas Measured by Cirrus HD-OCT (Mean ± Standard Deviation)
Control (n = 80) Glaucoma P1* P2† P3†
All (n = 80) Mild (n = 40) Moderate to Advanced (n = 40)
Average 305.85 ± 55.29 164.36 ± 50.80 174.18 ± 48.04 154.54 ± 52.54 <0.001 <0.001 0.479
Quadrant
 Superior 322.28 ± 52.09 176.91 ± 75.06 184.89 ± 87.46 168.9 ± 60.49 <0.001 <0.001 0.908
 Nasal 354.73 ± 85.69 194.70 ± 73.55 205.99 ± 79.45 183.41 ± 66.39 <0.001 <0.001 0.744
 Inferior 351.05 ± 60.37 176.59 ± 69.25 191.75 ± 54.42 161.43 ± 79.38 <0.001 <0.001 0.158
 Temporal 195.35 ± 49.34 109.24 ± 41.23 114.07 ± 34.33 104.40 ± 47.59 <0.001 <0.001 1.000
Clock-hour
 12 332.28 ± 49.54 184.26 ± 82.28 193.85 ± 96.49 174.68 ± 65.17 <0.001 <0.001 0.709
1 362.61 ± 70.86 208.91 ± 89.41 221.50 ± 92.17 196.32 ± 74.13 <0.001 <0.001 0.585
2 359.69 ± 84.51 200.13 ± 80.71 212.59 ± 86.83 187.68 ± 73.26 <0.001 <0.001 0.648
3 337.41 ± 93.77 183.29 ± 79.56 192.15 ± 84.81 174.44 ± 74.14 <0.001 <0.001 1.000
4 367.09 ± 98.82 200.68 ± 76.22 213.24 ± 79.89 188.12 ± 71.33 <0.001 <0.001 0.740
5 398.8 ± 82.12 207.46 ± 70.77 223.97 ± 59.78 190.94 ± 77.67 <0.001 <0.001 0.232
6 377.68 ± 64.00 191.79 ± 87.99 206.68 ± 72.65 176.91 ± 99.94 <0.001 <0.001 0.319
7 276.64 ± 57.79 130.53 ± 67.53 144.62 ± 53.98 116.44 ± 77.05 <0.001 <0.001 0.188
8 200.33 ± 54.73 110.66 ± 43.86 119.15 ± 39.90 102.18 ± 46.52 <0.001 <0.001 0.488
9 179.16 ± 51.35 104.07 ± 44.42 105.79 ± 35.74 102.35 ± 52.18 <0.001 <0.001 1.000
 10 206.56 ± 51.09 112.97 ± 49.59 117.26 ± 56.32 108.68 ± 42.21 <0.001 <0.001 1.000
 11 270.84 ± 53.10 137.54 ± 67.47 139.32 ± 73.46 135.76 ± 61.97 <0.001 <0.001 1.000
The relative amount of RNFL and rim loss in each clock-hour sector is presented in Figure 2. As for the RNFL thickness, the amount of loss in 8 to 10, 3, and 4 clock-hour sectors ranged from 3% to 33%, whereas it ranged from 48% to 57% in other sectors. In contrast, the amount of rim area/thickness loss showed even distribution (range, 40%–59%) throughout all sectors. 
Figure 2.
 
Temporal, superior, nasal, inferior, and temporal topographic profile of RNFL thickness (A), neuroretinal rim area (B), and rim thickness (C) as measured by Cirrus HD-OCT in eyes with control (solid line) and glaucoma (dashed line) groups. Values at each clock-hour sector mean relative amount of loss (%) compared with control group. In superior and inferior areas, the amount of RNFL loss ranged from 48% to 57%, whereas it ranged from 3% to 33% in nasal and temporal areas. Apart from the RNFL thickness, the amount of rim area and thickness loss showed even distribution (40%–59%) in all areas, including nasal and temporal areas.
Figure 2.
 
Temporal, superior, nasal, inferior, and temporal topographic profile of RNFL thickness (A), neuroretinal rim area (B), and rim thickness (C) as measured by Cirrus HD-OCT in eyes with control (solid line) and glaucoma (dashed line) groups. Values at each clock-hour sector mean relative amount of loss (%) compared with control group. In superior and inferior areas, the amount of RNFL loss ranged from 48% to 57%, whereas it ranged from 3% to 33% in nasal and temporal areas. Apart from the RNFL thickness, the amount of rim area and thickness loss showed even distribution (40%–59%) in all areas, including nasal and temporal areas.
AUCs and sensitivities at a 90% specificity level of the average, quadrant, and clock-hour RNFL thickness, rim area, and rim thickness are presented in Tables 5 to 7. Among the various parameters, average RNFL thickness had the highest AUC/sensitivity (0.988/96.3%), followed by average rim thickness (0.980/96.3%) and average rim area (0.972/92.5%). 
Table 5.
 
Glaucoma Diagnostic Ability of Average, Quadrant, and Clock-Hour Retinal Nerve Fiber Layer Thickness Measured by Cirrus HD-OCT Expressed as the Area under the Receiver Operating Characteristic Curves (AUCs with 95% Confidence Interval [CI]) and Sensitivities (%) at a 90% Specificity Level
Table 5.
 
Glaucoma Diagnostic Ability of Average, Quadrant, and Clock-Hour Retinal Nerve Fiber Layer Thickness Measured by Cirrus HD-OCT Expressed as the Area under the Receiver Operating Characteristic Curves (AUCs with 95% Confidence Interval [CI]) and Sensitivities (%) at a 90% Specificity Level
Control vs. All Glaucoma Control vs. Mild Glaucoma Mild vs. Moderate to Advanced Glaucoma
AUC (95% CI) Sensitivity AUC (95% CI) Sensitivity AUC (95% CI) Sensitivity
Average 0.988 (0.976–1.000) 96.3 0.982 (0.964–1.000) 96.3 0.748 (0.630–0.866) 38.2
Quadrant
 Superior 0.966 (0.939–0.993) 91.3 0.955 (0.911–0.999) 90.0 0.666 (0.537–0.795) 32.4
 Nasal 0.776 (0.701–0.851) 33.8 0.717 (0.610–0.823) 31.3 0.652 (0.521–0.783) 38.2
 Inferior 0.932 (0.886–0.977) 72.5 0.926 (0.861–0.990) 88.8 0.765 (0.647–0.883) 47.1
 Temporal 0.749 (0.662–0.836) 12.5 0.697 (0.565–0.830) 38.0 0.650 (0.519–0.780) 26.5
Clock-hour
 12 0.934 (0.897–0.972) 81.3 0.924 (0.873–0.976) 81.3 0.632 (0.498–0.766) 26.5
1 0.933 (0.892–0.973) 80.0 0.928 (0.875–0.982) 83.8 0.541 (0.403–0.680) 17.6
2 0.859 (0.798–0.920) 61.2 0.819 (0.735–0.904) 46.3 0.618 (0.484–0.752) 26.5
3 0.515 (0.421–0.610) 7.5 0.442 (0.326–0.557) 7.5 0.633 (0.501–0.765) 32.4
4 0.678 (0.592–0.764) 20.0 0.619 (0.506–0.732) 16.3 0.635 (0.503–0.766) 29.4
5 0.876 (0.819–0.932) 60.0 0.807 (0.718–0.896) 51.3 0.702 (0.578–0.827) 44.1
6 0.919 (0.870–0.967) 76.3 0.899 (0.814–0.964) 75.0 0.762 (0.645–0.880) 44.1
7 0.879 (0.810–0.948) 83.8 0.872 (0.777–0.966) 80.0 0.699 (0.570–0.827) 23.5
8 0.726 (0.637–0.815) 10.0 0.662 (0.534–0.791) 10.0 0.693 (0.563–0.823) 29.4
9 0.614 (0.522–0.705) 15.0 0.553 (0.437–0.669) 12.5 0.625 (0.491–0.759) 20.6
 10 0.796 (0.716–0.877) 27.5 0.734 (0.607–0.860) 26.3 0.588 (0.452–0.724) 17.6
 11 0.906 (0.83–0.959) 70.0 0.845 (0.751–0.940) 53.8 0.669 (0.541–0.796) 29.4
RNFL thickness showed good diagnostic ability in superior and inferior quadrants and clock-hour sectors 11 to 2 and 5 to 7 (AUCs ≥ 0.859). However, the AUCs of RNFL thickness in nasal and temporal quadrants and clock-hour sectors 3, 4, and 8 to 10 ranged from 0.515 to 0.796 (Table 5). Quadrant and clock-hour rim area and thickness showed good glaucoma diagnostic ability in all areas (AUCs, 0.877–0.969, Tables 6 and 7). 
Table 6.
 
Glaucoma Diagnostic Ability of Average, Quadrant, and Clock-Hour Rim Area Measured by Cirrus HD Optical Coherence Tomography Expressed as the Area under the Receiver Operating Characteristic Curves (AUCs with 95% Confidence Interval [CI]) and Sensitivities (%) at a 90% Specificity Level
Table 6.
 
Glaucoma Diagnostic Ability of Average, Quadrant, and Clock-Hour Rim Area Measured by Cirrus HD Optical Coherence Tomography Expressed as the Area under the Receiver Operating Characteristic Curves (AUCs with 95% Confidence Interval [CI]) and Sensitivities (%) at a 90% Specificity Level
Control vs. All Glaucoma Control vs. Mild Glaucoma Mild vs. Moderate to Advanced Glaucoma
AUC (95% CI) Sensitivity AUC (95% CI) Sensitivity AUC (95% CI) Sensitivity
Average 0.972 (0.948–0.996) 92.5 0.969 (0.943–0.995) 91.3 0.643 (0.512–0.775) 32.4
Quadrant
 Superior 0.911 (0.857–0.966) 80.0 0.839 (0.739–0.940) 75.0 0.557 (0.417–0.697) 32.4
 Nasal 0.935 (0.894–0.975) 82.5 0.919 (0.864–0.975) 85.0 0.670 (0.540–0.799) 35.3
 Inferior 0.936 (0.895–0.978) 81.3 0.939 (0.891–0.988) 83.8 0.601 (0.465–0.737) 32.4
 Temporal 0.945 (0.909–0.981) 86.3 0.942 (0.897–0.987) 86.3 0.574 (0.437–0.712) 20.6
Clock-hour
 12 0.882 (0.819–0.945) 75.0 0.799 (0.686–0.913) 45.0 0.567 (0.427–0.707) 32.4
1 0.899 (0.851–0.948) 73.8 0.858 (0.783–0.934) 65.0 0.606 (0.472–0.741) 26.5
2 0.907 (0.859–0.956) 76.3 0.885 (0.815–0.955) 72.5 0.631 (0.497–0.766) 26.5
3 0.913 (0.866–0.961) 80.0 0.907 (0.849–0.964) 78.8 0.624 (0.89–0.758) 29.4
4 0.937 (0.899–0.975) 81.3 0.918 (0.863–0.973) 76.3 0.676 (0.547–0.806) 29.4
5 0.913 (0.867–0.959) 70.0 0.890 (0.828–0.952) 72.5 0.653 (0.521–0.785) 20.6
6 0.906 (0.851–0.960) 67.5 0.907 (0.838–0.975) 70.0 0.540 (0.401–0.679) 11.8
7 0.935 (0.895–0.975) 77.5 0.943 (0.901–0.986) 80.0 0.601 (0.464–0.738) 14.7
8 0.932 (0.893–0.972) 83.8 0.921 (0.872–0.970) 83.8 0.644 (0.512–0.775) 17.6
9 0.915 (0.871–0.960) 82.5 0.903 (0.846–0.961) 73.8 0.591 (0.455–0.726) 17.6
 10 0.920 (0.875–0.965) 72.5 0.918 (0.855–0.981) 72.5 0.499 (0.360–0.638) 11.8
 11 0.911 (0.856–0.966) 70.0 0.844 (0.742–0.947) 42.5 0.471 (0.329–0.614) 20.6
Table 7.
 
Glaucoma Diagnostic Ability of Average, Quadrant, and Clock-Hour Rim Thickness Measured by Cirrus HD Optical Coherence Tomography Expressed as the Area under the Receiver Operating Characteristic Curves (AUCs with 95% Confidence Interval [CI]) and Sensitivities (%) at a 90% Specificity Level
Table 7.
 
Glaucoma Diagnostic Ability of Average, Quadrant, and Clock-Hour Rim Thickness Measured by Cirrus HD Optical Coherence Tomography Expressed as the Area under the Receiver Operating Characteristic Curves (AUCs with 95% Confidence Interval [CI]) and Sensitivities (%) at a 90% Specificity Level
Control vs. All Glaucoma Control vs. Mild Glaucoma Mild vs. Moderate to Advanced Glaucoma
AUC (95% CI) Sensitivity AUC (95% CI) Sensitivity AUC (95% CI) Sensitivity
Average 0.980 (0.964–0.997) 96.3 0.976 (0.952–1.000) 96.3 0.605 (0.470–0.740) 20.6
Quadrant
 Superior 0.930 (0.883–0.977) 82.5 0.884 (0.797–0.970) 70.0 0.520 (0.380–0.659) 20.6
 Nasal 0.939 (0.900–0.978) 85.0 0.915 (0.851–0.978) 77.5 0.564 (0.427–0.702) 26.5
 Inferior 0.968 (0.939–0.997) 96.3 0.980 (0.961–1.000) 87.5 0.668 (0.537–0.800) 23.5
 Temporal 0.919 (0.876–0.962) 82.5 0.928 (0.883–0.972) 85.0 0.520 (0.380–0.661) 17.6
Clock-hour
 12 0.916 (0.861–0.971) 73.8 0.863 (0.761–0.964) 55.0 0.522 (0.382–0.661) 20.6
1 0.902 (0.848–0.956) 67.5 0.846 (0.751–0.941) 52.5 0.533 (0.415–0.692) 23.5
2 0.915 (0.867–0.964) 68.8 0.881 (0.805–0.958) 68.8 0.565 (0.428–0.703) 23.5
3 0.915 (0.870–0.961) 76.3 0.899 (0.832–0.967) 73.8 0.556 (0.418–0.694) 17.6
4 0.934 (0.893–0.974) 78.8 0.914 (0.847–0.981) 77.5 0.578 (0.441–0.714) 20.6
5 0.969 (0.945–0.993) 90.0 0.968 (0.940–0.996) 83.8 0.652 (0.521–0.783) 23.5
6 0.947 (0.908–0.987) 88.8 0.959 (0.926–0.992) 80.0 0.638 (0.504–0.772) 17.6
7 0.951 (0.918–0.984) 83.8 0.956 (0.922–0.989) 82.5 0.639 (0.504–0.775) 17.6
8 0.906 (0.859–0.953) 78.8 0.886 (0.823–0.948) 75.0 0.596 (0.459–0.732) 17.6
9 0.877 (0.822–0.933) 71.3 0.883 (0.821–0.945) 72.5 0.530 (0.389–0.671) 17.6
 10 0.907 (0.859–0.954) 72.5 0.936 (0.894–0.978) 80.0 0.468 (0.329–0.607) 8.8
 11 0.933 (0.890–0.975) 83.8 0.909 (0.840–0.979) 62.5 0.483 (0.343–0.624) 20.6
With respect to the discrimination between mild glaucoma and moderate to advanced glaucoma groups, no parameters of RNFL thickness, rim area, and rim thickness had good diagnostic ability (AUCs ≤ 0.765 for RNFL thickness; AUCs ≤ 0.676 for rim area; AUCs ≤ 0.668 for rim thickness, Tables 57). 
When the AUCs of RNFL thickness, rim area, and rim thickness were compared, no significant difference was found in global area and superior and inferior quadrants (AUCs, 0.932–0.988 for RNFL thickness, 0.911–0.980 for rim area and thickness, P values > 0.05). However, in nasal and temporal quadrants, 3, 4, and 8 to 10 clock-hour sectors, rim area and thickness had greater AUCs (AUCs, 0.877–0.945) than RNFL thickness (AUCs, 0.515–0.796, P values < 0.001, Tables 57, Figs. 3 and 4). 
Figure 3.
 
Receiver operating characteristic curves of rim area/thickness and RNFL thickness measured by Cirrus HD-OCT in nasal quadrant (A) and clock-hour sector 3 (B) and 4 (C). In these areas, rim area and thickness had better diagnostic ability compared with RNFL thickness for discrimination between healthy eyes and glaucoma eyes.
Figure 3.
 
Receiver operating characteristic curves of rim area/thickness and RNFL thickness measured by Cirrus HD-OCT in nasal quadrant (A) and clock-hour sector 3 (B) and 4 (C). In these areas, rim area and thickness had better diagnostic ability compared with RNFL thickness for discrimination between healthy eyes and glaucoma eyes.
Figure 4.
 
Receiver operating characteristic curves of rim area and thickness and RNFL thickness measured by Cirrus HD-OCT in temporal quadrant (A) and clock-hour sector 8 (B), 9 (C), and 10 (D). In these areas, rim area and thickness had better diagnostic ability compared with RNFL thickness for discrimination between healthy eyes and glaucoma eyes.
Figure 4.
 
Receiver operating characteristic curves of rim area and thickness and RNFL thickness measured by Cirrus HD-OCT in temporal quadrant (A) and clock-hour sector 8 (B), 9 (C), and 10 (D). In these areas, rim area and thickness had better diagnostic ability compared with RNFL thickness for discrimination between healthy eyes and glaucoma eyes.
When AUCs of average, quadrant, and clock-hour rim thickness and rim area were compared, no significant difference was found between the two parameters with respect to the discrimination between the control group and all glaucoma groups, control group and mild glaucoma group, and mild glaucoma group and moderate to advanced glaucoma group (P values > 0.05). 
Discussion
With regard to the glaucoma diagnostic ability of neuroretinal rim as determined by Cirrus HD-OCT, Mwanza et al. 4 reported that the average rim area, vertical rim thickness, and horizontal rim thickness had good diagnostic abilities (AUCs, 0.901–0.963). In another study using Cirrus HD-OCT, Sung et al. 5 reported that the AUCs of average rim area ranged from 0.797 to 0.937. These results are comparable to the AUCs of the present study (0.877–0.980). However, the diagnostic ability of sectorial rim assessment was not evaluated in the aforementioned studies. In our study, quadrant and clock-hour rim assessment had good glaucoma diagnostic abilities in all areas with similar AUCs. 
The diagnostic abilities of RNFL showed an uneven distribution in the present study; nasal and temporal RNFL thicknesses had lower AUCs than other areas. Leung et al. 1 reported that average RNFL thickness and superior and inferior quadrants RNFL thicknesses had good diagnostic abilities (AUCs, 0.949–0.962), whereas RNFL thicknesses of nasal quadrant and clock-hour sectors 2 to 4, 8, and 9 had lower AUCs (0.535–0.761). In another study, Park et al. 2 also reported lower AUCs of RNFL thicknesses in nasal and temporal quadrants and clock-hour sectors 2 to 4 and 8 to 10 (0.572–0.763) than other areas (0.826–0.963). These results are in agreement with the present study results. 
Lower diagnostic ability of RNFL thickness in nasal and temporal areas than superior and inferior areas may be explained by relatively lower amount of RNFL loss in nasal and temporal areas than in other areas. In superior and inferior areas, the amount of RNFL loss ranged from 48% to 57%, whereas it ranged from 3% to 33% in nasal and temporal areas. Apart from the RNFL thickness, the amount of rim area and thickness loss showed even distribution (40%–59%) in all areas, including nasal and temporal areas (Fig. 2). These differences in topographic distribution of RNFL and rim loss as determined by Cirrus HD-OCT may be a cause of differences in diagnostic abilities between RNFL thickness and rim area and thickness in nasal and temporal areas. 
Jonas et al. 7 reported that glaucomatous rim loss assessed by disc photographs occurred in all sectors with regional preferences depending on the stage of the disease. Strouthidis et al. 20 investigated the spatial pattern of longitudinal rim area decline by using the HRT and reported that the slopes of changes in nasal and temporal areas were less than those in superior and inferior areas. On the other hand, a study utilizing serial disc photographs reported that the main pattern of cup extension in eyes with ocular hypertension was generalized expansion, 6 which agrees with the present results; presently, the relative amount sectorial rim area and thickness loss showed even topographic distribution throughout all areas without spatial preference. This discrepancy may stem from several differences in study design. First, in previous studies, 7,20 eyes with ocular hypertension or glaucoma with high IOP were mainly enrolled, whereas in the present study 80% of the patients with mild glaucoma and 60% of the patients with moderate to advanced glaucoma had pretreatment IOP ≤ 21 mm Hg. Second, in the previous study, 20 the spatial pattern of rim change was assessed longitudinally, whereas RNFL and rim were cross-sectionally evaluated in the present study. Third, the differences in rim detection methodology should also be considered; cup margin and disc margin as determined by Cirrus HD-OCT may differ from those detected by disc photograph or HRT. 21 Further studies regarding the longitudinal topographic pattern of rim loss in eyes with different types of glaucoma and using various imaging devices may be needed. 
In the present study, no parameters of RNFL thickness and rim area and thickness showed good diagnostic abilities for the discrimination between mild glaucoma and moderate to advanced glaucoma groups. These results suggest that detection of glaucoma progression with RNFL thickness and rim area and thickness as determined by Cirrus HD-OCT may have limited clinical value; other studies also reported that glaucoma progression detection by RNFL thickness or rim area as measured by Cirrus HD-OCT may be less effective than visual field test or macular thickness measurement, especially in advanced glaucoma. 17,22  
When the RNFL thickness and rim area and thickness of mild glaucoma and moderate to advanced glaucoma groups were compared, significant differences were found in RNFL thicknesses of global area and superior, inferior, and temporal quadrants, whereas no significant differences were evident in rim area and thickness in all areas. These results imply that neuroretinal rim may not be changed in accordance with a decrease in RNFL thickness with respect to the stages of glaucomatous damage. Further study regarding the difference of sectorial neuroretinal rim and RNFL thickness change in the glaucoma development and progression is needed. 
Given that parameters with wider ranges may generate a greater amount of change, a wider range of change to rim thickness compared with RNFL thickness may be considered a possible cause of the better diagnostic ability in nasal and temporal areas. However, given that rim area (which had a narrow range of change) also had better diagnostic ability in nasal and temporal areas compared with RNFL thickness, we think that it cannot be explained by an artifact associated with the range of values. 
Sectorial rim thickness assessment has an advantage of its convenience without additional image-processing procedure. Rim thickness at each point also has diagnostic capability similar to rim area at the corresponding clock-hour sector in our study results. However, measurement of rim thickness at a specific point as was performed in the present study may have a limitation of not representing the entire clock-hour sector. We suggest that Cirrus HD-OCT software providing average rim thicknesses in clock-hour sectors may be useful for the neuroretinal rim assessment. 
In conclusion, sectorial neuroretinal rim assessment by Cirrus HD-OCT may enhance the glaucoma diagnostic ability, especially in nasal and temporal areas. Patterns in RNFL and rim changes measured by Cirrus HD-OCT may be different according to the stages of glaucomatous damage. 
References
Leung CK Cheung CY Weinreb RN . Retinal nerve fiber layer imaging with spectral-domain optical coherence tomography: a variability and diagnostic performance study. Ophthalmology . 2009;116:1257–1263. [CrossRef] [PubMed]
Park SB Sung KR Kang SY Kim KR Kook MS . Comparison of glaucoma diagnostic capabilities of Cirrus HD and Stratus optical coherence tomography. Arch Ophthalmol . 2009;127:1603–1609. [CrossRef] [PubMed]
Mwanza JC Chang RT Budenz DL . Reproducibility of peripapillary retinal nerve fiber layer thickness and optic nerve head parameters measured with Cirrus HD-OCT in glaucomatous eyes. Invest Ophthalmol Vis Sci . 2010;51:5724–5730. [CrossRef] [PubMed]
Mwanza JC Oakley JD Budenz DL Anderson DR . Ability of Cirrus HD-OCT optic nerve head parameters to discriminate normal from glaucomatous eyes. Ophthalmology . 2011;118:241–248. [CrossRef] [PubMed]
Sung KR Na JH Lee Y . Glaucoma diagnostic capabilities of optic nerve head parameters as determined by Cirrus HD optical coherence tomography. J Glaucoma . 2011; Jun 1. Epub ahead of print.
Pederson JE Anderson DR . The mode of progressive disc cupping in ocular hypertension and glaucoma. Arch Ophthalmol . 1980;98:490–495. [CrossRef] [PubMed]
Jonas JB Fernandez MC Sturmer J . Pattern of glaucomatous neuroretinal rim loss. Ophthalmology . 1993;100:63–68. [CrossRef] [PubMed]
Airaksinen PJ Tuulonen A Alanko HI . Rate and pattern of neuroretinal rim area decrease in ocular hypertension and glaucoma. Arch Ophthalmol . 1992;110:206–210. [CrossRef] [PubMed]
Oddone F Centofanti M Lester M . Sector-based analysis with the Heidelberg Retinal Tomograph 3 across disc sizes and glaucoma stages: a multicenter study. Ophthalmology . 2009;116:1106–1111. [CrossRef] [PubMed]
Leung CK Mohamed S Leung KS . Retinal nerve fiber layer measurements in myopia: an optical coherence tomography study. Invest Ophthalmol Vis Sci . 2006;47:5171–5176. [CrossRef] [PubMed]
Hwang YH Yoo C Kim YY . Myopic optic disc tilt and the characteristics of peripapillary retinal nerve fiber layer thickness measured by spectral-domain optical coherence tomography. J Glaucoma . 2011; 5 26. Epub ahead of print.
Hoyt WF Frisén L Newman NM . Fundoscopy of nerve fiber layer defects in glaucoma. Invest Ophthalmol Vis Sci . 1973;12:814–829.
Jeoung JW Kim SH Park KH Kim TW Kim DM . Quantitative assessment of diffuse retinal nerve fiber layer atrophy using optical coherence tomography: diffuse atrophy imaging study. Ophthalmology . 2010;117:1946–1952. [CrossRef] [PubMed]
Budenz DL . Atlas of Visual Fields . Philadelphia, PA: Lippincott-Raven; 1997:143–145.
Hodapp E Parrish RKII Anderson DR . Clinical Decisions in Glaucoma . St Louis: Mosby; 1993; 52–61.
Hwang YH Lee JY Kim YY . The effect of head tilt on the measurements of retinal nerve fibre layer and macular thickness by spectral-domain optical coherence tomography. Br J Ophthalmol . 2011;95:1547–1551. [CrossRef] [PubMed]
Leung CK Liu S Weinreb RN . Evaluation of retinal nerve fiber layer progression in glaucoma a prospective analysis with neuroretinal rim and visual field progression. Ophthalmology . 2011;118:1551–1557. [CrossRef] [PubMed]
Tape TG . Interpreting diagnostic tests. Available at: http://gim.unmc.edu/dxtests/Default.htm. Accessed September 23, 2011.
Hanley JA McNeil BJ . A method of comparing the areas under receiver operating characteristic curves derived from the same cases. Radiology . 1983;148:839–843. [CrossRef] [PubMed]
Strouthidis NG Gardiner SK Sinapis C Burgoyne CF Garway-Heath DF . The spatial pattern of neuroretinal rim loss in ocular hypertension. Invest Ophthalmol Vis Sci . 2009;50:3737–3742. [CrossRef] [PubMed]
Sharma A Oakley JD Schiffman JC Budenz DL Anderson DR . Comparison of automated analysis of Cirrus HD OCT spectral-domain optical coherence tomography with stereo photographs of the optic disc. Ophthalmology . 2011;118:1348–1357. [CrossRef] [PubMed]
Sung KR Sun JH Na JH Lee JY Lee Y . Progression detection capability of macular thickness in advanced glaucomatous eyes. Ophthalmology . 2011; Dec 17. Epub ahead of print.
Footnotes
 Disclosure: Y.H. Hwang, None; Y.Y. Kim, None
Figure 1.
 
An example of quadrant and clock-hour neuroretinal rim area and thickness and RNFL thickness measured by Cirrus HD-OCT in an eye with glaucoma. Rim area was determined as the area between the optic disc margin (black circle) and cup margin (red circle); neuroretinal rim thickness was defined as the distance between optic disc margin and cup margin at a specific point.
Figure 1.
 
An example of quadrant and clock-hour neuroretinal rim area and thickness and RNFL thickness measured by Cirrus HD-OCT in an eye with glaucoma. Rim area was determined as the area between the optic disc margin (black circle) and cup margin (red circle); neuroretinal rim thickness was defined as the distance between optic disc margin and cup margin at a specific point.
Figure 2.
 
Temporal, superior, nasal, inferior, and temporal topographic profile of RNFL thickness (A), neuroretinal rim area (B), and rim thickness (C) as measured by Cirrus HD-OCT in eyes with control (solid line) and glaucoma (dashed line) groups. Values at each clock-hour sector mean relative amount of loss (%) compared with control group. In superior and inferior areas, the amount of RNFL loss ranged from 48% to 57%, whereas it ranged from 3% to 33% in nasal and temporal areas. Apart from the RNFL thickness, the amount of rim area and thickness loss showed even distribution (40%–59%) in all areas, including nasal and temporal areas.
Figure 2.
 
Temporal, superior, nasal, inferior, and temporal topographic profile of RNFL thickness (A), neuroretinal rim area (B), and rim thickness (C) as measured by Cirrus HD-OCT in eyes with control (solid line) and glaucoma (dashed line) groups. Values at each clock-hour sector mean relative amount of loss (%) compared with control group. In superior and inferior areas, the amount of RNFL loss ranged from 48% to 57%, whereas it ranged from 3% to 33% in nasal and temporal areas. Apart from the RNFL thickness, the amount of rim area and thickness loss showed even distribution (40%–59%) in all areas, including nasal and temporal areas.
Figure 3.
 
Receiver operating characteristic curves of rim area/thickness and RNFL thickness measured by Cirrus HD-OCT in nasal quadrant (A) and clock-hour sector 3 (B) and 4 (C). In these areas, rim area and thickness had better diagnostic ability compared with RNFL thickness for discrimination between healthy eyes and glaucoma eyes.
Figure 3.
 
Receiver operating characteristic curves of rim area/thickness and RNFL thickness measured by Cirrus HD-OCT in nasal quadrant (A) and clock-hour sector 3 (B) and 4 (C). In these areas, rim area and thickness had better diagnostic ability compared with RNFL thickness for discrimination between healthy eyes and glaucoma eyes.
Figure 4.
 
Receiver operating characteristic curves of rim area and thickness and RNFL thickness measured by Cirrus HD-OCT in temporal quadrant (A) and clock-hour sector 8 (B), 9 (C), and 10 (D). In these areas, rim area and thickness had better diagnostic ability compared with RNFL thickness for discrimination between healthy eyes and glaucoma eyes.
Figure 4.
 
Receiver operating characteristic curves of rim area and thickness and RNFL thickness measured by Cirrus HD-OCT in temporal quadrant (A) and clock-hour sector 8 (B), 9 (C), and 10 (D). In these areas, rim area and thickness had better diagnostic ability compared with RNFL thickness for discrimination between healthy eyes and glaucoma eyes.
Table 1.
 
Clinical Characteristics of the Control and Glaucoma Groups (Mean ± Standard Deviation)
Table 1.
 
Clinical Characteristics of the Control and Glaucoma Groups (Mean ± Standard Deviation)
Control (n = 80) Glaucoma P1 P2 P3
All (n = 80) Mild (n = 40) Moderate to Advanced (n = 40)
Age (years) 55.39 ± 11.15 53.94 ± 11.17 53.59 ± 11.87 54.29 ± 10.58 0.433* 1.000 1.000
IOP (mm Hg) 16.18 ± 2.21 18.62 ± 4.46 17.26 ± 2.60 19.97 ± 5.47 <0.001* 0.332 <0.001
SE (D) −0.99 ± 0.67 −0.97 ± 0.83 −1.06 ± 0.78 −0.88 ± 0.87 0.814* 1.000 0.911
Axial length (mm) 24.05 ± 0.72 24.12 ± 0.60 24.05 ± 0.37 24.18 ± 0.77 0.506* 1.000 0.937
Disc size (mm2) 2.12 ± 0.30 2.13 ± 0.40 2.19 ± 0.32 2.08 ± 0.46 0.857* 1.000 1.000
MD (dB) −0.43 ± 0.65 −6.90 ± 4.79 −3.33 ± 1.27 −10.47 ± 4.32 <0.001 <0.001 <0.001
PSD (dB) 1.01 ± 0.56 7.44 ± 3.73 4.39 ± 1.82 10.49 ± 2.42 <0.001 <0.001 <0.001
Table 2.
 
Retinal Nerve Fiber Layer Thickness (μm) in Average, Quadrant, and Clock-Hour Areas Measured by Cirrus HD-OCT (Mean ± Standard Deviation)
Table 2.
 
Retinal Nerve Fiber Layer Thickness (μm) in Average, Quadrant, and Clock-Hour Areas Measured by Cirrus HD-OCT (Mean ± Standard Deviation)
Control (n = 80) Glaucoma P1* P2† P3†
All (n = 80) Mild (n = 40) Moderate to Advanced (n = 40)
Average 97.75 ± 7.86 70.63 ± 11.55 75.29 ± 9.50 65.97 ± 11.65 <0.001 <0.001 <0.001
Quadrant
 Superior 127.69 ± 13.48 82.69 ± 19.66 88.44 ± 18.47 76.94 ± 19.38 <0.001 <0.001 <0.001
 Nasal 71.72 ± 8.99 62.34 ± 8.53 64.88 ± 8.13 59.79 ± 8.26 <0.001 <0.001 0.012
 Inferior 125.18 ± 13.37 81.18 ± 22.01 89.18 ± 18.99 73.18 ± 22.17 <0.001 <0.001 0.001
 Temporal 66.44 ± 6.78 56.84 ± 12.16 60.00 ± 11.59 53.68 ± 12.05 <0.001 0.003 <0.001
Clock-hour
 12 134.61 ± 23.61 83.85 ± 24.92 89.24 ± 22.15 78.47 ± 26.66 <0.001 <0.001 0.200
1 123.06 ± 20.53 80.37 ± 19.42 81.41 ± 19.31 79.32 ± 19.78 <0.001 <0.001 1.000
2 89.59 ± 14.96 69.66 ± 11.88 72.24 ± 12.16 67.09 ± 11.19 <0.001 <0.001 0.360
3 59.59 ± 8.58 58.56 ± 10.19 61.26 ± 8.87 55.85 ± 10.82 0.506 1.000 0.148
4 65.96 ± 12.13 58.57 ± 9.42 60.91 ± 9.65 56.24 ± 8.71 <0.001 0.075 0.236
5 100.69 ± 18.11 73.37 ± 15.95 79.15 ± 16.87 67.59 ± 12.78 <0.001 <0.001 0.015
6 138.11 ± 21.91 84.71 ± 28.52 95.26 ± 26.74 74.15 ± 26.57 <0.001 <0.001 0.001
7 136.21 ± 14.55 84.62 ± 34.86 91.91 ± 29.87 77.32 ± 38.72 <0.001 <0.001 0.059
8 68.76 ± 9.87 59.04 ± 15.92 63.12 ± 13.36 54.97 ± 17.36 <0.001 0.096 0.028
9 54.18 ± 7.69 50.53 ± 8.83 52.68 ± 8.10 48.38 ± 9.12 0.008 1.000 0.093
 10 76.53 ± 8.61 60.85 ± 17.05 64.06 ± 18.09 57.65 ± 15.55 <0.001 <0.001 0.133
 11 125.34 ± 15.62 82.65 ± 25.32 90.50 ± 27.13 74.79 ± 20.94 <0.001 <0.001 0.004
Table 3.
 
Neuroretinal Rim Area (mm2) in Average, Quadrant, and Clock-Hour Areas Measured by Cirrus HD-OCT (Mean ± Standard Deviation)
Table 3.
 
Neuroretinal Rim Area (mm2) in Average, Quadrant, and Clock-Hour Areas Measured by Cirrus HD-OCT (Mean ± Standard Deviation)
Control (n = 80) Glaucoma P1* P2† P3†
All (n = 80) Mild (n = 40) Moderate to Advanced (n = 40)
Average 1.29 ± 0.20 0.76 ± 0.20 0.81 ± 0.19 0.72 ± 0.21 <0.001 <0.001 0.170
Quadrant
 Superior 0.35 ± 0.06 0.21 ± 0.08 0.23 ± 0.10 0.20 ± 0.06 <0.001 <0.001 0.220
 Nasal 0.34 ± 0.07 0.21 ± 0.06 0.23 ± 0.06 0.20 ± 0.06 <0.001 <0.001 0.180
 Inferior 0.36 ± 0.07 0.21 ± 0.08 0.22 ± 0.07 0.20 ± 0.08 <0.001 <0.001 0.703
 Temporal 0.24 ± 0.05 0.13 ± 0.05 0.14 ± 0.04 0.13 ± 0.05 <0.001 <0.001 0.609
Clock-hour
 12 0.13 ± 0.02 0.08 ± 0.03 0.08 ± 0.04 0.07 ± 0.02 <0.001 <0.001 0.095
1 0.12 ± 0.02 0.08 ± 0.03 0.08 ± 0.03 0.07 ± 0.02 <0.001 <0.001 0.296
2 0.12 ± 0.02 0.07 ± 0.02 0.08 ± 0.02 0.07 ± 0.02 <0.001 <0.001 0.200
3 0.11 ± 0.02 0.07 ± 0.02 0.07 ± 0.02 0.06 ± 0.02 <0.001 <0.001 0.411
4 0.12 ± 0.08 0.07 ± 0.02 0.08 ± 0.02 0.07 ± 0.02 <0.001 <0.001 0.190
5 0.13 ± 0.03 0.08 ± 0.02 0.08 ± 0.02 0.07 ± 0.02 <0.001 <0.001 0.217
6 0.13 ± 0.03 0.07 ± 0.04 0.07 ± 0.03 0.07 ± 0.04 <0.001 <0.001 1.000
7 0.11 ± 0.02 0.06 ± 0.03 0.06 ± 0.02 0.05 ± 0.03 <0.001 <0.001 0.802
8 0.08 ± 0.05 0.05 ± 0.02 0.05 ± 0.01 0.04 ± 0.02 <0.001 <0.001 0.186
9 0.07 ± 0.05 0.04 ± 0.02 0.04 ± 0.01 0.04 ± 0.02 <0.001 <0.001 0.438
 10 0.08 ± 0.05 0.04 ± 0.02 0.05 ± 0.02 0.04 ± 0.02 <0.001 <0.001 1.000
 11 0.10 ± 0.06 0.06 ± 0.03 0.06 ± 0.03 0.05 ± 0.02 <0.001 <0.001 1.000
Table 4.
 
Neuroretinal Rim Thickness (μm) in Average, Quadrant, and Clock-Hour Areas Measured by Cirrus HD-OCT (Mean ± Standard Deviation)
Table 4.
 
Neuroretinal Rim Thickness (μm) in Average, Quadrant, and Clock-Hour Areas Measured by Cirrus HD-OCT (Mean ± Standard Deviation)
Control (n = 80) Glaucoma P1* P2† P3†
All (n = 80) Mild (n = 40) Moderate to Advanced (n = 40)
Average 305.85 ± 55.29 164.36 ± 50.80 174.18 ± 48.04 154.54 ± 52.54 <0.001 <0.001 0.479
Quadrant
 Superior 322.28 ± 52.09 176.91 ± 75.06 184.89 ± 87.46 168.9 ± 60.49 <0.001 <0.001 0.908
 Nasal 354.73 ± 85.69 194.70 ± 73.55 205.99 ± 79.45 183.41 ± 66.39 <0.001 <0.001 0.744
 Inferior 351.05 ± 60.37 176.59 ± 69.25 191.75 ± 54.42 161.43 ± 79.38 <0.001 <0.001 0.158
 Temporal 195.35 ± 49.34 109.24 ± 41.23 114.07 ± 34.33 104.40 ± 47.59 <0.001 <0.001 1.000
Clock-hour
 12 332.28 ± 49.54 184.26 ± 82.28 193.85 ± 96.49 174.68 ± 65.17 <0.001 <0.001 0.709
1 362.61 ± 70.86 208.91 ± 89.41 221.50 ± 92.17 196.32 ± 74.13 <0.001 <0.001 0.585
2 359.69 ± 84.51 200.13 ± 80.71 212.59 ± 86.83 187.68 ± 73.26 <0.001 <0.001 0.648
3 337.41 ± 93.77 183.29 ± 79.56 192.15 ± 84.81 174.44 ± 74.14 <0.001 <0.001 1.000
4 367.09 ± 98.82 200.68 ± 76.22 213.24 ± 79.89 188.12 ± 71.33 <0.001 <0.001 0.740
5 398.8 ± 82.12 207.46 ± 70.77 223.97 ± 59.78 190.94 ± 77.67 <0.001 <0.001 0.232
6 377.68 ± 64.00 191.79 ± 87.99 206.68 ± 72.65 176.91 ± 99.94 <0.001 <0.001 0.319
7 276.64 ± 57.79 130.53 ± 67.53 144.62 ± 53.98 116.44 ± 77.05 <0.001 <0.001 0.188
8 200.33 ± 54.73 110.66 ± 43.86 119.15 ± 39.90 102.18 ± 46.52 <0.001 <0.001 0.488
9 179.16 ± 51.35 104.07 ± 44.42 105.79 ± 35.74 102.35 ± 52.18 <0.001 <0.001 1.000
 10 206.56 ± 51.09 112.97 ± 49.59 117.26 ± 56.32 108.68 ± 42.21 <0.001 <0.001 1.000
 11 270.84 ± 53.10 137.54 ± 67.47 139.32 ± 73.46 135.76 ± 61.97 <0.001 <0.001 1.000
Table 5.
 
Glaucoma Diagnostic Ability of Average, Quadrant, and Clock-Hour Retinal Nerve Fiber Layer Thickness Measured by Cirrus HD-OCT Expressed as the Area under the Receiver Operating Characteristic Curves (AUCs with 95% Confidence Interval [CI]) and Sensitivities (%) at a 90% Specificity Level
Table 5.
 
Glaucoma Diagnostic Ability of Average, Quadrant, and Clock-Hour Retinal Nerve Fiber Layer Thickness Measured by Cirrus HD-OCT Expressed as the Area under the Receiver Operating Characteristic Curves (AUCs with 95% Confidence Interval [CI]) and Sensitivities (%) at a 90% Specificity Level
Control vs. All Glaucoma Control vs. Mild Glaucoma Mild vs. Moderate to Advanced Glaucoma
AUC (95% CI) Sensitivity AUC (95% CI) Sensitivity AUC (95% CI) Sensitivity
Average 0.988 (0.976–1.000) 96.3 0.982 (0.964–1.000) 96.3 0.748 (0.630–0.866) 38.2
Quadrant
 Superior 0.966 (0.939–0.993) 91.3 0.955 (0.911–0.999) 90.0 0.666 (0.537–0.795) 32.4
 Nasal 0.776 (0.701–0.851) 33.8 0.717 (0.610–0.823) 31.3 0.652 (0.521–0.783) 38.2
 Inferior 0.932 (0.886–0.977) 72.5 0.926 (0.861–0.990) 88.8 0.765 (0.647–0.883) 47.1
 Temporal 0.749 (0.662–0.836) 12.5 0.697 (0.565–0.830) 38.0 0.650 (0.519–0.780) 26.5
Clock-hour
 12 0.934 (0.897–0.972) 81.3 0.924 (0.873–0.976) 81.3 0.632 (0.498–0.766) 26.5
1 0.933 (0.892–0.973) 80.0 0.928 (0.875–0.982) 83.8 0.541 (0.403–0.680) 17.6
2 0.859 (0.798–0.920) 61.2 0.819 (0.735–0.904) 46.3 0.618 (0.484–0.752) 26.5
3 0.515 (0.421–0.610) 7.5 0.442 (0.326–0.557) 7.5 0.633 (0.501–0.765) 32.4
4 0.678 (0.592–0.764) 20.0 0.619 (0.506–0.732) 16.3 0.635 (0.503–0.766) 29.4
5 0.876 (0.819–0.932) 60.0 0.807 (0.718–0.896) 51.3 0.702 (0.578–0.827) 44.1
6 0.919 (0.870–0.967) 76.3 0.899 (0.814–0.964) 75.0 0.762 (0.645–0.880) 44.1
7 0.879 (0.810–0.948) 83.8 0.872 (0.777–0.966) 80.0 0.699 (0.570–0.827) 23.5
8 0.726 (0.637–0.815) 10.0 0.662 (0.534–0.791) 10.0 0.693 (0.563–0.823) 29.4
9 0.614 (0.522–0.705) 15.0 0.553 (0.437–0.669) 12.5 0.625 (0.491–0.759) 20.6
 10 0.796 (0.716–0.877) 27.5 0.734 (0.607–0.860) 26.3 0.588 (0.452–0.724) 17.6
 11 0.906 (0.83–0.959) 70.0 0.845 (0.751–0.940) 53.8 0.669 (0.541–0.796) 29.4
Table 6.
 
Glaucoma Diagnostic Ability of Average, Quadrant, and Clock-Hour Rim Area Measured by Cirrus HD Optical Coherence Tomography Expressed as the Area under the Receiver Operating Characteristic Curves (AUCs with 95% Confidence Interval [CI]) and Sensitivities (%) at a 90% Specificity Level
Table 6.
 
Glaucoma Diagnostic Ability of Average, Quadrant, and Clock-Hour Rim Area Measured by Cirrus HD Optical Coherence Tomography Expressed as the Area under the Receiver Operating Characteristic Curves (AUCs with 95% Confidence Interval [CI]) and Sensitivities (%) at a 90% Specificity Level
Control vs. All Glaucoma Control vs. Mild Glaucoma Mild vs. Moderate to Advanced Glaucoma
AUC (95% CI) Sensitivity AUC (95% CI) Sensitivity AUC (95% CI) Sensitivity
Average 0.972 (0.948–0.996) 92.5 0.969 (0.943–0.995) 91.3 0.643 (0.512–0.775) 32.4
Quadrant
 Superior 0.911 (0.857–0.966) 80.0 0.839 (0.739–0.940) 75.0 0.557 (0.417–0.697) 32.4
 Nasal 0.935 (0.894–0.975) 82.5 0.919 (0.864–0.975) 85.0 0.670 (0.540–0.799) 35.3
 Inferior 0.936 (0.895–0.978) 81.3 0.939 (0.891–0.988) 83.8 0.601 (0.465–0.737) 32.4
 Temporal 0.945 (0.909–0.981) 86.3 0.942 (0.897–0.987) 86.3 0.574 (0.437–0.712) 20.6
Clock-hour
 12 0.882 (0.819–0.945) 75.0 0.799 (0.686–0.913) 45.0 0.567 (0.427–0.707) 32.4
1 0.899 (0.851–0.948) 73.8 0.858 (0.783–0.934) 65.0 0.606 (0.472–0.741) 26.5
2 0.907 (0.859–0.956) 76.3 0.885 (0.815–0.955) 72.5 0.631 (0.497–0.766) 26.5
3 0.913 (0.866–0.961) 80.0 0.907 (0.849–0.964) 78.8 0.624 (0.89–0.758) 29.4
4 0.937 (0.899–0.975) 81.3 0.918 (0.863–0.973) 76.3 0.676 (0.547–0.806) 29.4
5 0.913 (0.867–0.959) 70.0 0.890 (0.828–0.952) 72.5 0.653 (0.521–0.785) 20.6
6 0.906 (0.851–0.960) 67.5 0.907 (0.838–0.975) 70.0 0.540 (0.401–0.679) 11.8
7 0.935 (0.895–0.975) 77.5 0.943 (0.901–0.986) 80.0 0.601 (0.464–0.738) 14.7
8 0.932 (0.893–0.972) 83.8 0.921 (0.872–0.970) 83.8 0.644 (0.512–0.775) 17.6
9 0.915 (0.871–0.960) 82.5 0.903 (0.846–0.961) 73.8 0.591 (0.455–0.726) 17.6
 10 0.920 (0.875–0.965) 72.5 0.918 (0.855–0.981) 72.5 0.499 (0.360–0.638) 11.8
 11 0.911 (0.856–0.966) 70.0 0.844 (0.742–0.947) 42.5 0.471 (0.329–0.614) 20.6
Table 7.
 
Glaucoma Diagnostic Ability of Average, Quadrant, and Clock-Hour Rim Thickness Measured by Cirrus HD Optical Coherence Tomography Expressed as the Area under the Receiver Operating Characteristic Curves (AUCs with 95% Confidence Interval [CI]) and Sensitivities (%) at a 90% Specificity Level
Table 7.
 
Glaucoma Diagnostic Ability of Average, Quadrant, and Clock-Hour Rim Thickness Measured by Cirrus HD Optical Coherence Tomography Expressed as the Area under the Receiver Operating Characteristic Curves (AUCs with 95% Confidence Interval [CI]) and Sensitivities (%) at a 90% Specificity Level
Control vs. All Glaucoma Control vs. Mild Glaucoma Mild vs. Moderate to Advanced Glaucoma
AUC (95% CI) Sensitivity AUC (95% CI) Sensitivity AUC (95% CI) Sensitivity
Average 0.980 (0.964–0.997) 96.3 0.976 (0.952–1.000) 96.3 0.605 (0.470–0.740) 20.6
Quadrant
 Superior 0.930 (0.883–0.977) 82.5 0.884 (0.797–0.970) 70.0 0.520 (0.380–0.659) 20.6
 Nasal 0.939 (0.900–0.978) 85.0 0.915 (0.851–0.978) 77.5 0.564 (0.427–0.702) 26.5
 Inferior 0.968 (0.939–0.997) 96.3 0.980 (0.961–1.000) 87.5 0.668 (0.537–0.800) 23.5
 Temporal 0.919 (0.876–0.962) 82.5 0.928 (0.883–0.972) 85.0 0.520 (0.380–0.661) 17.6
Clock-hour
 12 0.916 (0.861–0.971) 73.8 0.863 (0.761–0.964) 55.0 0.522 (0.382–0.661) 20.6
1 0.902 (0.848–0.956) 67.5 0.846 (0.751–0.941) 52.5 0.533 (0.415–0.692) 23.5
2 0.915 (0.867–0.964) 68.8 0.881 (0.805–0.958) 68.8 0.565 (0.428–0.703) 23.5
3 0.915 (0.870–0.961) 76.3 0.899 (0.832–0.967) 73.8 0.556 (0.418–0.694) 17.6
4 0.934 (0.893–0.974) 78.8 0.914 (0.847–0.981) 77.5 0.578 (0.441–0.714) 20.6
5 0.969 (0.945–0.993) 90.0 0.968 (0.940–0.996) 83.8 0.652 (0.521–0.783) 23.5
6 0.947 (0.908–0.987) 88.8 0.959 (0.926–0.992) 80.0 0.638 (0.504–0.772) 17.6
7 0.951 (0.918–0.984) 83.8 0.956 (0.922–0.989) 82.5 0.639 (0.504–0.775) 17.6
8 0.906 (0.859–0.953) 78.8 0.886 (0.823–0.948) 75.0 0.596 (0.459–0.732) 17.6
9 0.877 (0.822–0.933) 71.3 0.883 (0.821–0.945) 72.5 0.530 (0.389–0.671) 17.6
 10 0.907 (0.859–0.954) 72.5 0.936 (0.894–0.978) 80.0 0.468 (0.329–0.607) 8.8
 11 0.933 (0.890–0.975) 83.8 0.909 (0.840–0.979) 62.5 0.483 (0.343–0.624) 20.6
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×