Steady-State Pattern Electroretinography in Eyes with Glaucoma and High Myopia

Figures & data

Table 1 Demographics and Clinical Characteristics of Study Participants

	Group G (n=16)	Group HM (n=16)	Group GHM (n=16)	p-value
Age, years, Mean (95% CI)	61.8 (58.5, 65.1)	56.4 (51.8, 61.1)	59.9 (56.1, 63.7)	0.13
Male, N (%)	8 (50.0)	10 (62.5)	11 (68.8)	0.54
Race (Chinese), N (%)	13 (81.25)	16 (100)	15 (93.75)	0.15
Spherical equivalent, D Mean (95% CI)	−0.28 (−0.90, 0.34)	−9.28 (−10.5, −8.1)	−8.68 (−9.9, −7.5)	<0.001^a
BCVA, LogMAR Mean (95% CI)	0.10 (0.04, 0.16)	0.14 (0.08, 0.19)	0.14 (0.09, 0.19)	0.49
HVF MD, dB Mean (95% CI)	−14.22 (−17.1, −11.3)	−2.62 (−3.8, −1.4)	−12.80 (−15.4, −10.2)	<0.001^b
HVF VFI, % Mean (95% CI)	60.8 (51.9, 69.6)	97.1 (95.7, 98.4)	65.9 (56.9, 74.9)	<0.001^c
OCT CDR Mean (95% CI)	0.79 (0.73, 0.85)	0.70 (0.64, 0.76)	0.76 (0.72, 0.80)	0.03^d
OCT RNFL thickness, µm Mean (95% CI)	63.0 (54.8, 71.2)	69.5 (73.8, 85.2)	60.6 (55.5, 65.6)	0.001^e

Notes: ^aGroup G vs Group HM p < 0.001; Group G vs Group GHM p < 0.001. ^bGroup G vs Group HM p < 0.001; Group HM vs Group GHM p < 0.001. ^cGroup G vs Group HM p < 0.001; Group HM vs Group GHM p < 0.001. ^dGroup G vs Group HM p = 0.03. ^eGroup G vs Group HM p = 0.001; Group HM vs Group GHM p < 0.001.

Abbreviations: BCVA, best corrected visual acuity; HVF, Humphrey visual field static automated perimetry; MD, mean deviation; VFI, visual field index; OCT, optical coherence tomography; CDR, cup:disc ratio; RNFL, retinal nerve fibre layer.

Table 2 Comparison of the Concentric Stimulus Fields Protocols Between the Three Groups

	Group G (n = 16)	Group HM (n = 16)	Group GHM (n = 16)	p-value
24 degrees setting
Mag 24°, µV Mean (95% CI)	1.01 (0.88–1.14)	1.10 (0.90–1.29)	0.99 (0.92–1.07)	0.95^a
MagD 24°, µV Mean (95% CI)	0.61 (0.45–0.76)	0.80 (0.58–1.01)	0.55 (0.44–0.66)	0.08
MagD/Mag ratio 24° Mean (95% CI)	0.59 (0.48–0.70)	0.70 (0.61–0.80)	0.55 (0.46–0.64)	0.06
SNR 24°, dB Mean (95% CI)	2.08 (0.85–3.30)	3.34 (1.98–4.71)	2.18 (1.29–3.06)	0.21
16 degrees setting
Mag 16°, µV Mean (95% CI)	0.83 (0.74–0.93)	0.87 (0.75–1.00)	0.84 (0.74–0.94)	0.85
MagD 16°, µV Mean (95% CI)	0.34 (0.26–0.42)	0.52 (0.37–0.67)	0.29 (0.22–0.36)	0.02^a,b
MagD/Mag ratio 16° Mean (95% CI)	0.40 (0.32–0.48)	0.58 (0.46–0.69)	0.35 (0.26–0.44)	0.002^c
SNR 16°, dB Mean (95% CI)	1.18 (0.57–1.79)	1.74 (0.83–2.65)	0.88 (0.43–1.33)	0.17

Notes: ^aIndependent samples Kruskal–Wallis test. ^bGroup G vs Group HM p = 0.17; Group G vs Group GHM p = 0.02. ^cGroup G vs Group HM p = 0.02; Group HM vs Group GHM p = 0.002.

Abbreviations: Mag, magnitude; MagD, magnitude D; MagD/Mag ratio, magnitude D to magnitude ratio; SNR, signal to noise ratio.

Table 3 Comparison of the Contrast Sensitivity Protocols Between the Three Groups

	Group G (n = 16)	Group HM (n = 16)	Group GHM (n = 16)	p-value
High contrast (Hc) setting
Mag Hc, µV Mean (95% CI)	0.93 (0.82–1.05)	0.96 (0.77–1.15)	0.84 (0.78–0.91)	0.70^a
MagD Hc, µV Mean (95% CI)	0.53 (0.39–0.68)	0.68 (0.48–0.89)	0.44 (0.32–0.56)	0.09
MagD/Mag ratio Hc Mean (95% CI)	0.55 (0.44–0.67)	0.68 (0.58–0.77)	0.53 (0.39–0.68)	0.18
SNR Hc, dB Mean (95% CI)	1.84 (0.76–2.93)	2.96 (1.71–4.22)	1.41 (0.81–2.00)	0.14^a
Low contrast (Lc) setting
Mag Lc, µV Mean (95% CI)	0.81 (0.70–0.91)	0.90 (0.77–1.03)	0.83 (0.76–0.90)	0.39
MagD Lc, µV Mean (95% CI)	0.38 (0.29–0.47)	0.47 (0.31–0.63)	0.39 (0.30–0.48)	0.80^a
MagD/Mag ratio Lc Mean (95% CI)	0.47 (0.38–0.56)	0.50 (0.38–0.62)	0.47 (0.37–0.57)	0.89
SNR Lc, dB Mean (95% CI)	0.83 (0.33–1.33)	1.54 (0.77–2.32)	0.71 (0.18–1.24)	0.10

Note: ^a Independent samples Kruskal–Wallis test.

Abbreviations: Mag, magnitude; MagD, magnitude D; MagD/MagD ratio, magnitude D to magnitude ratio; SNR, signal to noise ratio; Hc, high contrast setting; Lc, low contrast setting.

Figure 1 Diopsys PERG trace of a patient from group GHM. The right eye of this participant was included in the study and had spherical equivalent of −9.75D, visual field mean deviation −11.34dB and average retinal nerve fibre layer thickness of 61µm. Left: Concentric stimulus (ConStim) protocol with 24° (top) and 16° (bottom) settings. Signal quality was good (120dBµV). (A) demonstrates the waveform obtained. The vertical axis indicates the amplitude (µV) and the horizontal axis, the time between 0 and 200 milliseconds. (B) is the strip chart, reflecting the PERG recording with artifacts represented by pronounced vertical peaks. In this case, there were 0 artifacts recorded. (C) is the frequency distribution chart, indicating the PERG response at various frequencies. The Magnitude value is obtained at 15Hz. Right: Contrast Sensitivity (ConSen) protocol with high contrast (Hc) (top) and low contrast (Lc) (bottom) settings. Signal quality was similarly good (125dBµV).

Figure 2 Diopsys PERG trace of a patient from group G. The right eye of this participant was included in the study and had spherical equivalent of +0.50D, visual field mean deviation −12.51dB and average retinal nerve fibre layer thickness of 60µm. Left: Concentric stimulus (ConStim) protocol with 24° (top) and 16° (bottom) settings. Signal quality was good (87dBµV). Right: Contrast Sensitivity (ConSen) protocol with high contrast (Hc) (top) and low contrast (Lc) (bottom) settings. Signal quality was similarly good (82dBµV).

Figure 3 Diopsys PERG trace of a patient from group HM. The right eye of this participant was included in the study and had spherical equivalent of −10.87D, visual field mean deviation −17.69dB and average retinal nerve fibre layer thickness of 56µm. Left: Concentric stimulus (ConStim) protocol with 24° (top) and 16° (bottom) settings. Signal quality was good (96dBµV). Right: Contrast Sensitivity (ConSen) protocol with high contrast (Hc) (top) and low contrast (Lc) (bottom) settings. Signal quality was similarly good (86dBµV).

Table 4 Pearson Correlation Coefficients of MagD and MagD/Mag Ratio at 16° with the Optic Disc and Visual Field Parameter

	Spherical Equivalent	Visual Field MD	OCT RNFL Thickness
Magnitude D 16°	−0.23 (p = 0.11)	0.37 (p = 0.009)	0.43 (p = 0.002)
MagD/Mag ratio 16°	−0.25 (p = 0.09)	0.44 (p = 0.002)	0.48 (p = 0.001)

Abbreviations: MD, mean deviation; OCT, optical coherence tomography; RNFL, retinal nerve fibre layer.

Figure 4 Correlation plots of (A) MagD 16° and visual field mean deviation, (B) MagD/Mag ratio 16° and visual field mean deviation, (C) MagD 16° and optical coherence tomography retinal nerve fibre layer mean thickness and (D) MagD/Mag ratio 16° and optical coherence tomography retinal nerve fibre layer mean thickness.

Abbreviations: r, Pearson correlation coefficient; R², coefficient of determination; p, p-value.