Optical Coherence Tomography Parameters of Normal, Glaucoma Suspect, and Early Glaucoma Patients

Su Eun Park; Jin Kwon Jung; Ji Yong Jung; Song Hee Park

doi:10.3341/jkos.2007.48.10.1379

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Park, Jung, Jung, and Park: Optical Coherence Tomography Parameters of Normal, Glaucoma Suspect, and Early Glaucoma Patients

Original Article

J Korean Ophthalmol Soc 2007;48(10):1379-1387.

Published online: 30 August 2007

DOI: https://doi.org/10.3341/jkos.2007.48.10.1379

Optical Coherence Tomography Parameters of Normal, Glaucoma Suspect, and Early Glaucoma Patients

Su Eun Park, M.D., Jin Kwon Jung, M.D., Ji Yong Jung, M.D., Song Hee Park, M.D.

Department of Ophthalmology, College of Medicine, Soonchunhyang University, Seoul, Korea

Address reprint requests to Song Hee Park M.D., Department of Ophthalmology, College of Medicine, Soonchunhyang University #657 Hannam-dong, Yongsan-gu, Seoul 140-743, Korea, Tel: 82-2-709-9354, Fax: 82-2-798-7797, E-mail: Parksonghee55@hanmail.net

Received 31 January 2007 Accepted 4 July 2007

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

The objective of this study is to compare optic nerve head (ONH) analysis parameters and retinal nerve fiber layer (RNFL) thickness parameters as measured by optical coherence tomography (OCT) among age-matched normal eyes, glaucoma-suspect eyes, and early glaucomatous eyes; and to determine the discriminating parameter best suited to distinguish early glaucoma in age-matched normal eyes and glaucoma- suspect eyes.

Methods

One hundred two normal eyes, 72 glaucoma-suspect eyes, and 85 eyes with early glaucoma that had been submitted to OCT and Humphrey field analysis were enrolled in this study. Optic nerve head analysis values and RNFL thickness values with OCT scans were compared among all groups. Sensitivity and specificity for the detection of early glaucoma were determined with a receiver operating characteristic (ROC) curve.

Results

The best-suited parameters were determined to be from 0.637 to 0.753 in optic nerve head parameters and from 0.506 to 0.759 in RNFL thickness parameters calculated with the area under the ROC curve (AUROC). The average thickness for early glaucomatous eye (0.818) had the widest AUROC among all parameters. The sensitivity and specificity of RNFL thickness parameter were determined to be 49.4% and 93.1%, respectively, at the cut-off value 92.17 pm.

Conclusions

Optic nerve head and RNFL thickness parameters measured with OCT have relatively high sensitivity and specificity for detecting early glaucomatous eyes. Furthermore, they may provide clinically relevant information for the detection of early glaucomatous damage and for monitoring glaucomatous changes.

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

References

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Figure 1.

Receiver operating characteristic (ROC) curve of horizontal integrated rim width in control group and early glaucoma group. It has the best discriminating capability. Cut-off value 1.529 mm² yields high diagnostic value with sensitivity 72.9% and specificity 65.5%.

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Figure 2.

Receiver operating characteristic (ROC) curve of average thickness in control group and early glaucoma group. It has the best discriminating capability among thickness parameters. Cut off value 92.17 pm yields high diagnostic value with sensitivity 49.4% and specificity 93.1%.

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Table 1.

Criteria for each subject

Enrolled group	Criteria
All subjects	Best corrected visual acuity >0.5
	Refractive error <4 diopter (Spherical equivalent)
	No history of systemic disease, trauma, and secondary causes of glaucoma
	No significant cataract or vitreous opacity
Normal subject	Intraocular pressure (IOP) ≤21 mmHg with repeated measure
	Normal finding on ocular examination
	Absence of glaucomatous optic neuropathy (GON) defined as vertical cup/disk asymmetry between fellow eyes of 0.2 or less cup/disk ratio of 0.6 or less
	Intact neural rim without peripapillary hemorrhages, notches, localized pallor, or RNFL (Retinal nerve fiber layer) defects
	Normal visual field defined as mean deviation and pattern standard deviation within 95% confidence limits
	Glaucoma hemifield test (GHT): within normal limit
Glaucoma suspect	Intraocular pressure (IOP) ≤ 21 mmHg with repeated measure
	Presence of glaucomatous optic neuropathy (GON)
	Normal visual field (GHT: within normal limit or borderline)
Early glaucoma	Glaucomatous optic neuropathy plus
	Glaucomatous visual field loss in the corresponding hemifield location
	Based on liberal criteria
	GHT : outside normal limit
	Mean deviation >-6dB in Humphrey field analyzer
Enrolled group	Criteria
All subjects	Best corrected visual acuity >0.5
	Refractive error <4 diopter (Spherical equivalent)
	No history of systemic disease, trauma, and secondary causes of glaucoma
	No significant cataract or vitreous opacity
Normal subject	Intraocular pressure (IOP) ≤ 21 mmHg with repeated measure
	Normal finding on ocular examination
	Absence of glaucomatous optic neuropathy (GON) defined as vertical cup/disk asymmetry between fellow eyes of 0.2 or less cup/disk ratio of 0.6 or less
	Intact neural rim without peripapillary hemorrhages, notches, localized pallor, or RNFL (Retinal nerve fiber layer) defects
	Normal visual field defined as mean deviation and pattern standard deviation within 95% confidence limits
	Glaucoma hemifield test (GHT): within normal limit
Glaucoma suspect	Intraocular pressure (IOP) ≤ 21 mmHg with repeated measure
	Presence of glaucomatous optic neuropathy (GON)
	Normal visual field (GHT: within normal limit or borderline)
Early glaucoma	Glaucomatous optic neuropathy plus
	Glaucomatous visual field loss in the corresponding hemifield location
	Based on liberal criteria
	GHT: outside normal limit
	Mean deviation > −6dB in Humphrey field analyzer

Table 2.

Backgrounds of subjects

	Normal	Glaucoma suspect	Early glaucoma	P value^Π
Number of patient	102	72	85
Age (years)	52.40±9.41	51.51±9.5 8	52.76± 11.02	.728
MD^* (dB)	-1.76±.06	-1.79±1.17	-3.52± 1.38	.000
R.E.^† (diopter)	-1.26±2.19	-0.59± 1.72	-0.53±2.17	.217
Cup/disk ratio	0.42±0.12	0.61±0.13	0.65±0.21	.000
CCT^‡ (gm)	518.7±37.0	520.5±43.7	522.7±25.9	.835
IOP^§ (mmHg)	16.23±3.11	16.40±3.09	16.78±5.14	.623

MD^*: mean deviation.

R.E.^†: refractive error.

CCT^‡: central corneal thickness.

IOP^§: intraocular pressure.

P value^Π: statistical significance was tested by ANOVA.

Table 3.

Comparison of OCT measured optic nerve head (ONH) analysis parameter value among groups

Measurement	Normal	Glaucoma suspect	Early glaucoma	P^*
vert. integrated rim vol. (mm³)	0.27±0.16	0.22±0.13	0.18±0.14	.000^†
horiz. Integrated Rim Area (mm²)	1.62±0.20	1.60±0.21	1.39±0.24	.000^‡
rim area (mm²)	1.54±0.35	1.44±0.33	1.20±0.45	.000^‡
cup/disk area ratio	0.42±0.14	0.51±0.13	0.55±0.16	.000^†
cup/disk horiz. ratio	0.69±0.15	0.76±0.12	0.78±0.13	.000^†
cup/disk vert. ratio	0.59±0.13	0.66±0.10	0.68±0.14	.012^†

P^*: ANOVA, Tuckey Kramer test was performed in normal, glaucoma suspect, and early glaucoma patient.

^†: Normal group significantly different from early glaucoma and glaucoma suspect groups.

^‡: Early glaucoma group significantly different from normal and glaucoma suspect groups.

Table 4.

Comparison of OCT measured retinal nerve fiber layer (RNFL) thickness (pm) analysis parameter value among groups

Measurement	Normal	Glaucoma Suspect	Early Glaucoma	P^*	P^†	P^‡	P^§
Average	104.2±9.7	103.6±9.6	92.8±14.5	.000	.938	.000	.000
Superior quadrant	126.7±14.0	125.8± 15.4	114.3± 19.4	.000	.922	.000	.000
Temporal quadrant	73.7± 10.0	74.1±11.7	66.4± 15.4	.000	.982	.000	.000
Inferior quadrant	137.1±16.8	131.6± 16.0	118.9±22.2	.000	.140	.000	.000
Nasal quadrant	79.1± 15.6	82 7±18.8	7 4.1 ± 17.3	.007	.351	.116	.005
Smax^Π	159.5±19.4	159.2± 18.6	146.4±22.9	.000	.993	.000	.000
Imax^#	170.3±18.8	167.4± 17.6	150.3±27.3	.000	.658	.000	.000
CH (Clock hour) 12	130.4±20.2	129.1±23.4	117.3±24.5	.000	.928	.000	.003
CH11	133.1±19.4	132.7±22.0	119.5±27.8	.000	.994	.000	.001
CH10	86.4±14.5	86.2±16.8	77.7±19.6	.001	.995	.001	.005
CH9 (temporal)	60.3±10.4	60.8± 10.9	5 5.4± 14.9	.008	.961	.021	.019
CH8	77.7±14.9	78.4± 15.7	68.9± 18.4	.000	.965	.001	.001
CH7	142.4±20.2	137.3±23.4	121.1±30.3	.000	.381	.000	.000
CH6 (inferior)	149.1±22.9	144.2±20.6	130.9±27.4	.000	.384	.000	.002
CH5	118.9±23.3	117.9±23.0	106.2±21.7	.000	.955	.001	.004
CH4	77.9± 16.8	81.1±16.0	72.9±18.6	.001	.451	.111	.008
CH3 (nasal)	64.7± 13.9	66.1±16.5	61.3± 16.0	.125	.820	.290	.125
CH2	91. 1±22.6	93.2±22.0	84.0±22.3	.024	.819	.081	.030
CHl	117.1± 19.4	115.4± 19.0	102.5±25.6	.000	.868	.000	.001

Imax^δ = Inferior maximum.

P^*: ANOVA test was performed in normal, glaucoma suspect, and early glaucoma patient.

P^†: Tuckey-Kramer test was performed in normal and glaucoma suspect.

P^‡: Tuckey-Kramer test was performed in normal and early glaucoma.

P^§: Tuckey-Kramer test was performed in glaucoma suspect and early glaucoma.

Smax^Π=Superior maximum;

Imax^#= Inferior maximum.

Table 5.

Area under the receiver operating characteristic (AUROC) curve, best combination of sensitivity/specificity with specificity ≥90% for the individual OCT parameters detecting early glaucoma

Measurement	AUROC^‡	Cut off value	Sensitivity	Specificity
ONH^* parameters
horiz. integrated rim area	0.753	1.35	47.1%	92.0%
rim area	0.729	1.11	45.9%	91.4%
vert. integrated rim vol.	0.713	0.13	41.2%	91.4%
RNFL^† thickness parameters
Imax^§	0.718	144.5	37.6%	92.0%
average thickness	0.759	92.5	50.6%	92.0%
inferior	0.728	111.5	35.3%	93.7%

ONH^* = optic nerve head;

RNFL^† = retinal nerve fiber layer;

AUROC^‡ = area under the ROC curve;

Im ax^§ = Inferior maximum.

Table 6.

Area under the receiver operating characteristic (AUROC) curve, best combination of sensitivity/specificity with specificity ≥80% for the individual OCT parameters detecting early glaucoma

Measurement	AUROC^‡	Cut off value	Sensitivity	Specificity
ONH^* parameters
horiz. integrated rim area	0.753	1.42	51.8	83.9
rim area	0.729	1.56	55.3	81.6
vert. integrated rim vol.	0.713	0.14	48.2	84.5
RNFL^† thickness parameters Imax^§
	0.718	154.5	54.1	81.0
average thickness	0.759	94.3	58.8	81.0
Inferior	0.728	120.5	50.6	81.6

ONH^* = optic nerve head;

RNFL^† = retinal nerve fiber layer;

AUROC^‡ = area under the ROC curve;

Imax^§ = Inferior maximum.

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