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Kang, Lee, and Uhm: Diagnostic Ability of Stratus OCT Using Korean Normative Database for Early Detection of Normal-Tension Glaucoma
Original Article

J Korean Ophthalmol Soc 2008;49(5):798-810.

Published online: 7 September 2008

DOI: https://doi.org/10.3341/jkos.2008.49.5.798

Diagnostic Ability of Stratus OCT Using Korean Normative Database for Early Detection of Normal-Tension Glaucoma

Sung Min Kang, M.D.1, Seung Bok Lee, M.D.2, Ki Bang Uhm, M.D.1

1Department of Ophthalmology, Hanyang University College of Medicine, Seoul, Korea

2Lee's Eye Clinic, Hongsung, Korea

Address reprint requests to Ki Bang Uhm, M.D. Department of Ophthalmology, College of Medicine, Hanyang University Hospital #17 Haengdang-dong, Sungdong-gu, Seoul 133-792, Korea Tel: 82-2-2290-8570, Fax: 82-2-2291-8517, E-mail: KBUhm@hanyang.ac.kr

Received 31 May 2007       Accepted 12 December 2007

Copyright © 2008 Korean Ophthalmological Society

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose

To determine if korean normative database improve diagnostic ability of Stratus OCT for detection of glaucoma.

Methods

Peripapillary retinal nerve fiber layer (RNFL) and optic nerve head regions were measured using a Stratus OCT. The normative data were collected from 129 normal individuals. We obtained values at the 5% and 1% levels according to the disc area stratified into equal thirds to minimize the error by the individual variation of optic disc size and these levels were considered abnormal. One eye of each 94 normal-tension glaucoma patients with early visual field defects (mean deviaton = −3.84±1.40dB) and 87 another normal subjects were enrolled. Glaucoma was defined by visual field defects.

Results

The use of Korean normative database had higher sensitivity and no significant difference of specificity than that of a Stratus OCT except for a few parameters. The criteria that show the highest diagnostic ability were 1 ≥ quadrants RNFL thickness abnormal at the < 5% when using a Korean normative database (sensitivity = 81.9%, specificity = 81.6%) and 1 ≥ clock hours abnormal at the < 5% when using a Stratus OCT normative database (sensitivity = 71.3%, specificity = 87.4%) (p=0.004, p=0.180, respectively, McNemar test).

Conclusions

The criterion using a Korean normative database had higher sensitivity and no difference of specificity compared with criterion using a Stratus OCT normative database. The best criterion using a Korean normative database may be helpful for early detection of normal-tension glaucoma.

Keywords: Glaucoma, Optical coherence tomography, Optic nerve, Retinal nerve fiber layer thickness

References

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Figure 1.
The scatter diagram of average retinal nerve fiber layer thickness (RNFL) in 87 normal subjects and 94 early normal tension glaucoma (NTG) patients. The use of 5% cut off values from a Korean normative database had higher sensitivity than that from a Stratus OCT.
jkos-49-798f1.tif
Table 1.
Bottom or top 1 percentile and 5 percentile values according to the disc area based on normative database of 129 Korean subjects
  Optic disc size∗
  Small Medium Large
Percentile 1 5 1 5 1 5
Subjects 43 44 42
Optic disc area (mm2) (mean±SD) 2.04±0.21 2.53±0.09 3.17±0.39
 (minimum to maximum) 1.458 ∼ 2,321 2.349 ∼ 2.691 2.703 ∼ 4.049
Optic nerve head parameters            
 VIRA (mm3) (bottom) 0.093 0.103 0.024 0.103 0.063 0.111
 HIRW (mm2) (bottom) 0.977 1.034 0.532 1.167 1.220 1.264
 Cup area (mm2) (top) 1.212 1.171 1.939 1.537 2.536 2.383
 Rim area (mm2) (bottom) 0.788 0.805 1.028 1.028 0.743 1.138
 C/D area ratio (top) 0.595 0.584 0.801 0.592 0.773 0.640
 Horizontal C/D ratio (top) 0.903 0.891 0.917 0.870 0.897 0.890
 Vertical C/D ratio (top) 0.752 0.697 0.890 0.768 0.870 0.762
RNFL thickness parameters (µm) (bottom)            
 Average 84.6 85.0 86.4 89.6 87.7 91.7
 Superior quadrant 96.0 104.2 77.0 100.5 103.0 107.5
 Temporal quadrant 53.0 53.0 39.0 56.0 47.0 49.9
 Inferior quadrant 98.0 106.8 87.0 97.0 116.0 117.6
 Nasal quadrant 39.0 47.0 48.0 52.3 60.0 61.5
 O'clock hour segment            
 12 (superior) 87.0 93.0 79.0 82.8 97.0 100.8
 11 83.0 91.4 77.0 91.0 98.0 102.6
 10 58.0 61.4 51.0 63.8 58.0 63.1
 9 (temporal) 43.0 43.4 28.0 39.5 28.0 37.3
 8 45.0 49.4 38.0 44.8 33.0 49.6
 7 92.0 93.4 90.0 91.3 110.0 114.3
 6 (inferior) 91.0 110.4 72.0 86.8 106.0 109.5
 5 77.0 79.0 61.0 68.5 87.0 87.5
 4 42.0 48.2 48.0 48.3 57.0 61.2
 3 (nasal) 38.0 38.8 35.0 44.5 43.0 47.6
 2 38.0 53.6 52.0 62.0 60.0 61.5
 1 84.0 87.0 63.0 80.5 78.0 85.3

∗ Optic disc size were divided into tertile; SD = standard deviation; VIRA = vertical integrated rim area; HIRW = horizontal integrated rim width; RNFL = retinal nerve fiber layer.

Table 2.
Characteristics of the study groups
  Normal eyes Early glaucomatous eyes P-value
Subjects 87 94  
Age (years) 57.7±10.9 59.1±11.1 0.38
Gender (male:female) 30:57 39:55 0.36
Refractive error (diopter) 0.02±1.82 -0.68±2.22 0.02
MD (dB) -1.14±1.40 -3.84±1.40 <0.001
CPSD (dB) 1.59±0.32 3.92±2.09 <0.001

Values are number or means±standard deviation; MD = mean deviation; CPSD = corrected pattern standard deviation.

Table 3.
Comparison of Stratus OCT parameters between the 2 groups
  Normal eyes (n=88) Early glaucomatous eyes (n=52) P-value
Optic disc parameters      
 Disc area (mm2) 2.59±0.53 2.94±0.69 <0.001
 VIRA (mm3) 0.36±0.20 0.15±0.20 <0.001
 HIRW (mm2) 1.65±0.23 1.26±0.29 <0.001
 Cup area (mm2) 0.89±0.51 1.88±0.86 <0.001
 Rim area (mm2) 1.70±0.39 1.02±0.43 <0.001
 C/D area ratio 0.33±0.14 0.63±0.18 <0.001
 Horizontal C/D ratio 0.62±0.15 0.82±0.14 <0.001
 Vertical C/D ratio 0.51±0.12 0.75±0.13 <0.001
RNFL thickness parameters (µm)      
 Average 104.1±10.4 83.6±19.8 <0.001
 Superior quadrant 126.1±17.9 101.4±25.1 <0.001
 Temporal quadrant 75.3±12.6 65.5±16.0 <0.001
 Inferior quadrant 136.3±16.2 101.5±30.0 <0.001
 Nasal quadrant 78.4±15.9 66.5±21.4 <0.001
O'clock hour segment      
 12 (superior) 129.3±24.1 103.8±31.5 <0.001
 11 133.7±24.0 105.6±29.0 <0.001
 10 88.7±16.4 76.2±21.4 <0.001
 9 (temporal)) 58.3±10.8 55.2±14.6 0.111
 8 79.1±16.8 65.6±20.4 <0.001
 7 147.3±20.2 105.3±38.6 <0.001
 6 (inferior) 146.7±23.8 109.0±37.2 <0.001
 5 114.8±21.7 90.4±26.3 <0.001
 4 77.7±19.1 67.7±23.4 0.002
 3 (nasal) 64.1±14.5 55.4±18.3 <0.001
 2 93.6±21.4 75.7±26.7 <0.001
 1 115.7±21.8 93.9±28.1 <0.001

Values are means±standard deviation; VIRA = vertical integrated rim area; HIRW = horizontal integrated rim width; RNFL = retinal nerve fiber layer.

Table 4.
Comparison of sensitivity and specificity between the 2 groups (group 1; classification based on the 1% cut-off value of a Korean normative database, group 2; classification based on the 1% cut-off value of a Stratus OCT normative database)
  Korean normative database < 1%
 Stratus OCT normative database < 1%
 P-value∗ P-value†
Sn (%) Sp (%) Sn (%) Sp (%) Sn Sp
RNFLT parameters (bottom)            
 Average 56.4 92.0 18.1 98.9 <0.001 0.063
 Superior quadrant 37.2 94.3 13.8 98.9 <0.001 0.125
 Temporal quadrant 13.8 97.7 6.4 100 0.039 0.500
 Inferior quadrant 57.4 96.6 25.5 100 <0.001 0.250
 Nasal quadrant 24.5 94.3 6.4 100 <0.001 0.063
O'clock hour segment            
 12 (superior) 33.0 94.3 9.6 98.9 <0.001 0.125
 11 31.9 97.7 11.7 100 <0.001 0.500
 10 17.0 98.9 9.6 100 0,039 1.000
 9 (temporal) 6.4 95.4 5.3 98.9 1.000 0.375
 8 6.4 98.9 7.4 100 1.000 1.000
 7 42.6 97.7 23.4 100 <0.001 0.500
 6 (inferior) 38.3 98.9 18.1 100 <0.001 1.000
 5 36.2 94.3 11.7 100 <0.001 0.063
 4 23.4 95.4 7.4 98.9 <0.001 0.250
 3 (nasal) 17.0 97.7 4.3 100 <0.001 0.500
 2 21.3 97.7 8.5 100 0,004 0.500
 1 24.5 96.6 8.5 100 <0.001 0.250
Different criteria            
 1 ≥ quadrants RNFLT abnormal 69.1 88.5 34.0 98.9 <0.001 0.004
 Superior or inferior quadrant RNFLT abnormal 57.7 93.1 23.1 98.9 <0.001 0.063
 1 ≥ o'clock hours RNFLT abnormal 78.7 83.9 53.2 97.7 <0.001 <0.001

∗ P-values indicate difference in sensitivity between the two groups;

† P-values indicate difference in specficity between the two groups; Sn = sensitivity; Sp = specificity; RNFLT = retinal nerve fiber layer thickness.

Table 5.
Comparison of sensitivity and specificity between the 2 groups (group 1; classification based on the 5% cut off value of a Korean normative database, group 2; classification based on the 5% cut-off value of a Stratus OCT normative database)
  Korean normative database < 5%
 Stratus OCT normative database < 5%
 P-value∗ P-value†
Sn (%) Sp (%) Sn (%) Sp (%) Sn Sp
RNFLT parameters (bottom)            
 Average 68.1 90.8 38.3 97.7 <0.001 0.031
 Superior quadrant 57.4 89.7 36.2 96.6 <0.001 0.031
 Temporal quadrant 17.0 96.6 13.8 98.9 0.453 0.500
 Inferior quadrant 61.7 94.3 40.4 98.9 <0.001 0.125
 Nasal quadrant 30.9 92.0 20.2 97.7 0.013 0.063
O'clock hour segment            
 12 (superior) 38.3 93.1 19.1 97.7 <0.001 0.125
 11 38.3 94.3 28.7 97.7 0.012 0.250
 10 24.5 95.4 14.9 100 0.012 0.125
 9 (temporal) 9.6 94.3 9.6 97.7 1.000 0.250
 8 18.1 98.9 14.9 98.9 0.250 1.000
 7 45.7 97.7 36.2 97.7 0.012 1.000
 6 (inferior) 47.9 96.6 31.9 98.9 <0.001 0.500
 5 40.4 94.3 18.1 98.9 <0.001 0.125
 4 33.0 93.1 11.7 98.9 <0.001 0.063
 3 (nasal) 27.7 90.8 14.9 98.9 0.004 0.016
 2 34.0 95.4 25.5 96.6 0.077 1.000
 1 39.4 92.0 22.3 97.7 <0.001 0.063
Different criteria            
 1 ≥ quadrants RNFLT abnormal 81.9 81.6 62.8 92.0 <0.001 0.004
 Superior or inferior quadrant RNFLT abnormal 78.7 86.2 56.4 95.4 <0.001 0.008
 1 ≥ o'clock hours RNFLT abnormal 84.0 74.7 71.3 87.4 0.004 0.001

∗ P-values indicate difference in sensitivity between the two groups;

† P-values indicate difference in specficity between the two groups; Sn = sensitivity; Sp = specificity; RNFLT = retinal nerve fiber layer thickness.

Table 6.
Comparison of sensitivity and specificity between the 2 groups (group 1; classification based on the 1% cut off value of a Korean normative database, group 2; classification based on the 5% cut-off value of a Korean normative database)
  Korean normative database < 1%
 Korean normative database < 5%
 P-value∗ P-value†
Sn (%) Sp (%) Sn (%) Sp (%) Sn Sp
Optic nerve head parameters            
 VIRA (bottom) 20.2 100 52.1 95.4 <0.001 0.125
 HIRW (bottom) 23.4 100 30.9 98.9 0.016 1.000
 Cup area (top) 25.5 98.9 41.5 98.9 <0.001 1.000
 Rim area (bottom) 28.7 100 52.1 97.7 <0.001 0.500
 C/D area ratio (top) 21.3 100 53.2 97.7 <0.001 0.500
 Horizontal C/D ratio (top) 33.0 97.7 38.3 95.4 0.063 0.500
 Vertical C/D ratio (top) 16.0 100 51.1 98.9 <0.001 1.000
RNFLT parameters (bottom)            
 Average 56.4 92.0 68.1 90.8 0.001 1.000
 Superior quadrant 37.2 94.3 57.4 89.7 <0.001 0.125
 Temporal quadrant 13.8 97.7 17.0 96.6 0.250 1.000
 Inferior quadrant 57.4 96.6 61.7 94.3 0.125 0.500
 Nasal quadrant 24.5 94.3 30.9 92.0 0.031 0.500
O'clock hour segment            
 12 (superior) 33.0 94.3 38.3 93.1 0.063 1.000
 11 31.9 97.7 38.3 94.3 0.031 0.250
 10 17.0 98.9 24.5 95.4 0.016 0.250
 9 (temporal) 6.4 95.4 9.6 94.3 0.250 1.000
 8 6.4 98.9 18.1 98.9 0.001 1.000
 7 42.6 97.7 45.7 97.7 0.250 1.000
 6 (inferior) 38.3 98.9 47.9 96.6 0.004 0.500
 5 36.2 94.3 40.4 94.3 0.125 1.000
 4 23.4 95.4 33.0 93.1 0.004 0.500
 3 (nasal) 17.0 97.7 27.7 90.8 0.002 0.031
 2 21.3 97.7 34.0 95.4 <0.001 0.500
 1 24.5 96.6 39.4 92.0 <0.001 0.125
Different criteria            
 1 ≥ ONH parameters abnormal 50.0 95.4 69.1 93.1 <0.001 0.500
 1 ≥ quadrants RNFLT abnormal 69.1 88.5 81.9 81.6 <0.001 0.031
 Superior or inferior quadrant RNFLT abnormal 66.0 93.1 78.7 86.2 <0.001 0.031
 1 ≥ o'clock hours RNFLT abnormal 78.7 83.9 84.0 74.7 0.063 0.008

∗ P-values indicate difference in sensitivity between the two groups;

† P-values indicate difference in specficity between the two groups; Sn = sensitivity; Sp = specificity; VIRA = vertical integrated rim area. HIRW = horizontal integrated rim width; RNFLT = retinal nerve fiber layer thickness; ONH = optic nerve head.

Table 7.
Comparison of sensitivity and specificity between the 2 groups (group 1; classification based on the 1% cut-off value of a Stratus OCT normative database, group 2; classification based on the 5% cut-off value of a Stratus OCT normative database)
  Stratus OCT normative database < 1%
 Stratus OCT normative database < 5%
 P-value∗ P-value†
Sn (%) Sp (%) Sn (%) Sp (%) Sn Sp
RNFLT parameters (bottom)            
 Average 18.1 98.9 38.3 97.7 <0.001 1.000
 Superior quadrant 13.8 98.9 36.2 96.6 <0.001 0.500
 Temporal quadrant 6.4 100 13.8 98.9 0.016 1.000
 Inferior quadrant 25.5 100 40.4 98.9 0.001 1.000
 Nasal quadrant 6.4 100 20.2 97.7 <0.001 0.500
O'clock hour segment            
 12 (superior) 9.6 98.9 19.1 97.7 0,012 1,000
 11 11.7 100 28.7 97.7 <0.001 0.500
 10 9.6 100 14.9 100 0.063 1.000
 9 (temporal) 5.3 98.9 9.6 97.7 0.125 1.000
 8 7.4 100 14.9 98.9 0.016 1.000
 7 23.4 100 36.2 97.7 <0.001 0.500
 6 (inferior) 18.1 100 31.9 98.9 <0.001 1.000
 5 11.7 100 18.1 98.9 0.031 1.000
 4 7.4 98.9 11.7 98.9 0.125 1.000
 3 (nasal) 4.3 100 14.9 98.9 0.002 1.000
 2 8.5 100 25.5 96.6 <0.001 0.250
 1 8.5 100 22.3 97.7 <0.001 0.500
Different criteria            
 1 ≥ quadrants RNFLT abnormal 34.0 98.9 62.8 92.0 <0.001 0.031
 Sup or inf quadrant RNFLT abnormal 30.9 98.9 56.4 95.4 <0.001 0.250
 1 ≥ o'clock hours RNFLT abnormal 53.2 97.7 71.3 87.4 <0.001 0.004

∗ P-values indicate difference in sensitivity between the two groups;

† P-values indicate difference in specficity between the two groups; Sn = sensitivity; Sp = specificity; RNFLT = retinal nerve fiber layer thickness; Sup = superior; Inf = inferior.

Table 8.
The parameters and criteria that show the highest diagnostic ability for discriminating early glaucomatous eyes from normal eyes
  Sn (%) Sp (%) AROC
The best single parameter using a Korean normative database      
 C/D area ratio > 95% from the ONH parameters 53.2 97.7 0.754
 Average RNFL thickness < 5% from the RNFL thickness parameters 68.1 90.8 0.794
The best single parameter using a Stratus OCT normative database      
 Inferior quadrant RNFL thickness < 5% from the RNFL thickness parameters 40.4 98.9 0.696
The best criterion using a Korean normative database      
 1 ≥ quadrants RNFL thickness abnormal at the < 5% from the RNFL criteria 81.9 81.6 0.818
The best criterion using a Stratus OCT normative database      
 1 ≥ o'clock hours RNFL thickness abnormal at the < 5% from the RNFL criteria 71.3 87.4 0.793

Sn = sensitivity; Sp = specificity; AROC = area under the receiver operating characteristic curve; ONH = optic nerve head; RNFL = retinal nerve fiber layer.

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