Macular ganglion cell asymmetry for detecting paracentral scotoma in early glaucoma

Figures & data

Figure 1 The Cirrus HD-OCT macular cube 200×200 protocol provides regional GCIPL thickness in six wedge-shaped sectors.

Abbreviation: GCIPL, ganglion cell-inner plexiform layer.

Table 1 Demographic and clinical characteristics of the study population

	Normal (N=58)	Early glaucoma with PCS (N=58)	P-value
Age (years)	51.1±13.4	54.9±9.7	0.089
SE (D)	−3.13±3.4	−3.33±3.4	0.751
AL (mm)	25.89±1.5	25.20±1.6	0.327
IOP (mmHg)	16.31±3.6	17.14±3.5	0.208
CCT (µm)	550.79±32.4	566.51±45.9	0.053
MD (dB)	−1.07±1.5	−2.94±1.3	<0.001

Abbreviations: AL, axial length; CCT, central corneal thickness; IOP, intraocular pressure; MD, mean deviation; PCS, paracentral scotoma; SE, spherical equivalent.

Table 2 Comparison of cpRNFL thickness, GCIPL thickness and asymmetry measurements, and ONH parameters between two groups

Parameters	Normal (N=58)	Early glaucoma with PCS (N=58)	P-value
cpRNFL thickness
Average	97.43±8.67	80.28±9.64	<0.001
Superior	117.79±15.78	100.45±18.94	<0.001
Nasal	66.09±10.72	66.36±11.04	0.892
Inferior	121.78±16.99	89.91±13.47	<0.001
Temporal	82.76±13.82	64.17±13.44	<0.001
GCIPL thickness
Average	81.24±5.85	70.97±8.46	<0.001
Minimum	78.53±6.69	59.31±11.88	<0.001
Superonasal	83.48±6.61	77.64±13.08	0.003
Superior	81.69±6.54	73.91±11.45	<0.001
Superotemporal	80.43±5.64	72.03±9.86	<0.001
Inferotemporal	81.38±5.65	64.47±11.22	<0.001
Inferior	78.57±6.32	64.31±10.23	<0.001
Inferonasal	81.76±6.69	73.60±10.99	<0.001
GCIPL absolute difference
I–S	6.41±4.96	29.86±23.62	<0.001
IT–ST	2.47±1.77	12.19±9.34	<0.001
IT–SN	3.72±2.44	16.00±11.88	<0.001
ST–IN	3.47±3.22	8.84±7.07	<0.001
SN–IN	2.97±2.02	7.41±6.85	<0.001
GCIPL asymmetry ratio
I/S	0.98±0.03	0.91±0.14	<0.001
IT/ST	1.01±0.04	0.91±0.18	<0.001
IT/SN	0.98±0.05	0.85±0.20	<0.001
ST/IN	0.99±0.58	0.99±0.17	0.743
SN/IN	1.02±0.04	1.06±0.13	0.044
GCIPL asymmetry index
Log10 (I/S)	0.01±0.01	0.06±0.05	<0.001
Log10 (IT/ST)	0.01±0.01	0.08±0.06	<0.001
Log10 (IT/SN)	0.02±0.01	0.10±0.07	<0.001
Log10 (ST/IN)	0.02±0.02	0.05±0.04	<0.001
Log10 (SN/IN)	0.02±0.01	0.04±0.04	<0.001
ONH
Rim area	1.23±0.22	0.92±0.23	<0.001
Disc area	1.83±0.52	2.04±0.51	0.025
Average C/D	0.51±0.19	0.72±0.12	<0.001
Vertical C/D	0.48±0.19	0.72±0.13	<0.001
Cup volume	0.18±0.16	0.47±0.29	<0.001

Abbreviations: C/D, cup-to-disc ratio; cpRNFL, circumferential peripapillary retinal nerve fiber layer; GCIPL, ganglion cell-inner plexiform layer; I, inferior hemisphere; IT, inferotemporal; IN, inferonasal; ONH, optic nerve head; PCS, paracentral scotoma; S, superior hemisphere; ST, superotemporal; SN, superonasal.

Table 3 AUROC and pAUROC values for cpRNFL thickness, GCIPL thickness, GCIPL asymmetry measurements, and ONH parameters

Parametres	AUROC (95% CI)	pAUROC at 90% specificity (95% CI)	pAUROC at 95% specificity (95% CI)
cpRNFL thickness
Average	0.914 (0.863–0.965)	0.058 (0.039–0.078)	0.023 (0.012–0.034)
Superior	0.761 (0.674–0.847)	0.029 (0.015–0.043)	0.012 (0.004–0.019)
Nasal	0.526 (0.420–0.633)	0.001 (−0.007–0.010)	N/A
Inferior	0.934 (0.889–0.978)	0.060 (0.035–0.085)	0.020 (0.004–0.035)
Temporal	0.830 (0.758–0.903)	0.052 (0.039–0.065)	0.025 (0.018–0.032)
GCIPL thickness
Average	0.834 (0.762–0.906)	0.049 (0.035–0.063)	0.023 (0.016–0.030)
Minimum	0.911 (0.857–0.964)	0.067 (0.047–0.087)	0.028 (0.013–0.042)
Superonasal	0.625 (0.520–0.730)	0.032 (0.018–0.046)	0.014 (0.007–0.021)
Superior	0.708 (0.612–0.804)	0.043 (0.030–0.056)	0.020 (0.013–0.027)
Superotemporal	0.756 (0.666–0.846)	0.046 (0.032–0.059)	0.022 (0.016–0.029)
Inferotemporal	0.896 (0.836–0.955)	0.069 (0.057–0.082)	0.033 (0.027–0.039)
Inferior	0.871 (0.805–0.936)	0.058 (0.044–0.073)	0.028 (0.021–0.034)
Inferonasal	0.725 (0.632–0.817)	0.032 (0.017–0.048)	0.012 (0.003–0.021)
GCIPL absolute difference
I–S	0.836 (0.760–0.912)	0.063 (0.050–0.077)	0.029 (0.022–0.037)
IT–ST	0.877 (0.811–0.943)	0.067 (0.054–0.080)	0.032 (0.025–0.038)
IT–SN	0.845 (0.768–0.922)	0.066 (0.053–0.080)	0.031 (0.024–0.038)
ST–IN	0.753 (0.665–0.841)	0.037 (0.022–0.051)	0.015 (0.007–0.024)
SN–IN	0.679 (0.580–0.777)	0.039 (0.026–0.052)	0.018 (0.012–0.025)
GCIPL asymmetry ratio
I/S	0.684 (0.574–0.793)	0.059 (0.047–0.071)	0.029 (0.022–0.035)
IT/ST	0.676 (0.565–0.787)	0.058 (0.045–0.070)	0.028 (0.021–0.034)
IT/SN	0.777 (0.682–0.872)	0.067 (0.055–0.078)	0.033 (0.027–0.039)
ST/IN	0.523 (0.409–0.638)	0.031 (0.018–0.044)	0.013 (0.006–0.019)
SN/IN	0.620 (0.515–0.725)	0.009 (0.001–0.018)	0.004 (0.001–0.008)
GCIPL asymmetry index
Log10 (I/S)	0.846 (0.772–0.920)	0.065 (0.052–0.078)	0.031 (0.024–0.038)
Log10 (IT/ST)	0.894 (0.832–0.956)	0.071 (0.059–0.083)	0.034 (0.028–0.041)
Log10 (IT/SN)	0.867 (0.794–0.940)	0.075 (0.064–0.086)	0.037 (0.031–0.043)
Log10 (ST/IN)	0.773 (0.688–0.859)	0.042 (0.026–0.058)	0.018 (0.009–0.026)
Log10 (SN/IN)	0.698 (0.602–0.794)	0.044 (0.032–0.057)	0.021 (0.015–0.028)
ONH
Rim area	0.848 (0.777–0.919)	0.051 (0.034–0.068)	0.021 (0.011–0.031)
Disc area	0.628 (0.526–0.729)	0.009 (0.0002–0.018)	0.003 (−0.0004–0.007)
Average C/D	0.877 (0.813–0.941)	0.057 (0.041–0.072)	0.025 (0.017–0.033)
Vertical C/D	0.910 (0.854–0.966)	0.073 (0.061–0.085)	0.034 (0.027–0.042)
Cup volume	0.828 (0.752–0.904)	0.040 (0.018–0.063)	0.013 (0.002–0.024)

Abbreviations: AUROC, area under the receiver operating characteristic curves; C/D, cup-to-disc ratio; cpRNFL, circumferential peripapillary retinal nerve fiber layer; GCIPL, ganglion cell-inner plexiform layer; I, inferior hemisphere; IN, inferonasal; IT, inferotemporal; N/A, nonapplicable; ONH, optic nerve head; pAUROC, partial area under the receiver operating characteristic curves; S, superior hemisphere; SE, standard error; SN, superonasal; ST, superotemporal.

Table 4 P-values for pairwise comparison of AUROC values and pAUROC values between the best measure of each GCIPL asymmetry analysis and cpRNFL, GCIPL, and ONH parameters

	AUROC	pAUROC at 90% specificity	pAUROC at 95% specificity
IT–ST vs minimal GCIPL thickness	0.434	0.960	0.584
IT–ST vs inferior cpRNFL thickness	0.165	0.646	0.154
IT–ST vs vertical C/D	0.736	0.504	0.618
IT/SN vs minimal GCIPL thickness	0.017	0.946	0.486
IT/SN vs inferior cpRNFL thickness	0.004	0.650	0.116
IT/SN vs vertical C/D	0.020	0.469	0.814
Log (IT/ST) vs minimal GCIPL thickness	0.685	0.412	0.403
Log (IT/ST) vs inferior cpRNFL thickness	0.205	0.860	0.090
Log (IT/ST) vs vertical C/D	0.711	0.080	0.971

Abbreviations: AUROC, area under the receiver operating characteristic curves; C/D, cup-to-disc ratio; cpRNFL, circumferential peripapillary retinal nerve fiber layer; GCIPL, ganglion cell-inner plexiform layer; IT, inferotemporal; ONH, optic nerve head; pAUROC, partial area under the receiver operating characteristic curves; SN, superonasal; ST, superotemporal.

Figure 2 AUROC values for OCT parameters to discriminate early glaucoma with paracentral scotoma from normal controls.

Note: The inferior RNFL thickness had the largest AUROC value (0.934), followed by average RNFL thickness (0.914), minimum GCIPL thickness (0.911), vertical C/D (0.910), IT GCIPL thickness (0.896), and IT/ST asymmetry index (0.894).
Abbreviations: AUROC, area under the receiver operating characteristic curve; C/D, cup-to-disc ratio; GCIPL, ganglion cell-inner plexiform layer; IT, inferotemporal; OCT, optical coherence tomography; RNFL, retinal nerve fiber layer; ROC, receiver operating characteristic; ST, superotemporal.