Electroretinogram Changes Following Sequential Panretinal Photocoagulation for Proliferative Diabetic Retinopathy

Figures & data

Table 1 Changes in a-Wave, b-Wave, and 30 Hz Flicker in Different Time Points

	Type	Amplitude				Latency
		Pair	MD(%)	SD	P-value	Pair	MD(%)	SD	P-value
a wave	D.A 3 ERG	FS and Pre	−2.42(10.42)	1.36	<0.001	FS and Pre	0.71(2.22)	1.16	0.041
		SS and Pre	−4.7(20.31)	1.57	<0.001	SS and Pre	1.36(4.38)	1.63	0.020
		TS and Pre	−6.05(26.36)	1.54	<0.001	TS and Pre	2.11(6.85)	1.93	0.005
		FS and SS	−2.28(10.97)	1.2	0.003	FS and SS	0.65(2.07)	0.62	0.003
		SS and TS	−1.35(7.56)	0.61	0.003	SS and TS	0.75(2.34)	0.58	0.003
		1.5M and TS	1.11(6.72)	0.51	0.003	1.5M and TS	−0.85(2.51)	0.79	0.003
		1.5M and Pre	−4.95(21.70)	0.33	0.003	1.5M and Pre	1.26(4.23)	1.25	0.014
	L.A 3 ERG	FS and Pre	−2.34(10.53)	1.23	<0.001	FS and Pre	0.56(2.59)	0.50	0.004
		SS and Pre	−4.36(19.78)	1.86	<0.001	SS and Pre	1.11(5.04)	0.47	<0.001
		TS and Pre	−5.52(24.99)	2.36	<0.001	TS and Pre	1.57(7.15)	0.65	<0.001
		FS and SS	−2.34(10.39)	1.23	0.003	FS and SS	0.55(2.41)	0.39	0.026
		SS and TS	−2.03(6.62)	0.92	0.003	SS and TS	0.46(1.99)	0.26	0.003
		1.5M and TS	0.66(4.16)	0.28	0.003	1.5M and TS	−0.55(2.30)	0.22	0.021
		1.5M and Pre	−5.39(25.13)	1.80	0.003	1.5M and Pre	1.02(4.59)	0.02	0.003
	D.A 10 ERG	FS and Pre	−11.69(8.17)	2.32	<0.001	FS and Pre	0.85(2.89)	0.69	0.002
		SS and Pre	−24.35(17.2)	4.34	<0.001	SS and Pre	1.50(5.05)	0.70	<0.001
		TS and Pre	−34.2(23.71)	9.08	<0.001	TS and Pre	2.10(7.12)	0.65	<0.001
		FS and SS	−11.69(9.63)	2.32	0.003	FS and SS	0.65(2.12)	2.32	0.003
		SS and TS	−12.65(8.6)	2.76	0.003	SS and TS	0.6(1.99)	0.6	0.003
		1.5M and TS	4.14(3.82)	1.29	0.003	1.5M and TS	−0.7(2.20)	0.4	0.003
		1.5M and Pre	−30.07(21.08)	6.81	0.032	1.5M and Pre	1.40(4.71)	1.27	0.003
b wave	D.A 0.01 ERG	FS and Pre	−10.0(9.90)	1.65	<0.001	FS and Pre	3.09(3.22)	2.41	0.002
		SS and Pre	−20.34(20.19)	1.99	<0.001	SS and Pre	6.95(7.17)	3.51	<0.001
		TS and Pre	−27.26(27.15)	2.86	<0.001	TS and Pre	10.35(10.64)	4.22	<0.001
		FS and SS	−10.34(11.44)	1.29	0.003	FS and SS	3.86(3.82)	2.07	0.003
		SS and TS	−6.93(8.77)	2.04	0.003	SS and TS	3.4(3.23)	1.6	0.003
		1.5M and TS	8.54(12.40)	3.37	0.003	1.5M and TS	−4.75(4.29)	2.84	0.003
		1.5M and Pre	−18.72(18.31)	2.67	0.011	1.5M and Pre	5.60(5.71)	1.27	0.003
	L.A 3 ERG	FS and Pre	−6.03(2.95)	3.24	<0.001	FS and Pre	0.47(0.52)	0.26	<0.001
		SS and Pre	−15.98(7.82)	6.68	<0.001	SS and Pre	1.47(1.61)	0.69	<0.001
		TS and Pre	−24.45(11.96)	7.19	<0.001	TS and Pre	2.25(2.48)	0.78	<0.001
		FS and SS	−9.95(5.03)	4.27	0.003	FS and SS	1(1.09)	0.75	0.003
		SS and TS	−8.46(4.50)	2.7	0.003	SS and TS	0.78(0.85)	0.59	0.003
		1.5M and TS	6.86(3.86)	3.67	0.003	1.5M and TS	−1.12(1.19)	0.54	0.003
		1.5M and Pre	−17.40(18.36)	0.54	0.003	1.5M and Pre	0.48(1.12)	0.12	0.004
	D.A 3 ERG	FS and Pre	−7.66(8.04)	3.09	<0.001	FS and Pre	0.19(0.48)	0.35	0.049
		SS and Pre	−15.02(15.81)	4.26	<0.001	SS and Pre	0.59(1.41)	0.33	<0.001
		TS and Pre	−21.45(21.00)	4.32	<0.001	TS and Pre	0.99(2.16)	0.31	<0.001
		FS and SS	−7.35(8.47)	2.35	0.003	FS and SS	0.4(0.93)	0.12	0.003
		SS and TS	−6.43(8.01)	2.71	0.003	SS and TS	0.4(0.92)	0.13	0.003
		1.5M and TS	4.05(5.68)	2.81	0.003	1.5M and TS	−0.52(1.19)	0.2	0.003
		1.5M and Pre	−17.58(8.64)	0.82	0.003	1.5M and Pre	1.15(1.26)	0.14	0.003
	D.A 10 ERG	FS and Pre	−16.56(4.67)	5.89	<0.001	FS and Pre	1.77(3.16)	0.86	<0.001
		SS and Pre	−34.34(9.76)	7.62	<0.001	SS and Pre	3.51(6.31)	1.22	0.001
		TS and Pre	−55.34(15.57)	11.01	<0.001	TS and Pre	4.23(7.75)	3.20	<0.001
		FS and SS	−17.77(5.34)	4.92	0.003	FS and SS	1.74(3.06)	1.2	0.003
		SS and TS	−21(6.42)	9.22	0.003	SS and TS	0.72(1.36)	3.18	0.050
		1.5M and TS	9.03(3.05)	3.91	0.003	1.5M and TS	−0.91(1.41)	2.49	0.050
		1.5M and Pre	−46.31(13.07)	5.76	0.003	1.5M and Pre	3.32(5.94)	0.42	0.049
Flicker 30 Hz ERG		FS and Pre	−4.35(8.43)	1.56	<0.001	FS and Pre	0.55(1.69)	0.21	<0.001
		SS and Pre	−9.10(17.50)	2.15	<0.001	SS and Pre	1.14(3.46)	0.34	<0.001
		TS and Pre	−14.00(26.88)	3.25	<0.001	TS and Pre	1.70(5.17)	0.39	<0.001
		FS and SS	−4.75(9.90)	1.29	0.003	FS and SS	0.58(1.74)	0.18	0.003
		SS and TS	−4.91(11.41)	1.76	0.003	SS and TS	0.56(1.65)	0.13	0.003
		1.5M and TS	6.24(16.58)	1.91	0.003	1.5M and TS	−0.91(2.62)	0.3	0.003
		1.5M and Pre	−7.77(14.84)	0.99	0.001	1.5M and Pre	0.79(2.39)	0.05	0.001

Table 2 Changes in Scotopic and Photopic a-Wave and b-Wave in Different Time Points

Type	Amplitude				Latency
	Pair	MD(%)	SD	P-value	Pair	MD(%)	SD	P-value
Scotopic a	FS and Pre	−7.05(9.89)	5.10	<0.001	FS and Pre	0.78(1.81)	0.94	0.001
	SS and Pre	−14.52(18.66)	10.55	<0.001	SS and Pre	1.43(4.71)	1.23	<0.001
	TS and Pre	−20.13(25.3)	15.74	<0.001	TS and Pre	−2.10(6.89)	1.41	<0.001
	FS and SS	−4.29(1.82)	7.50	<0.001	FS and SS	0.48(1.55)	0.76	<0.001
	SS and TS	−5.53(7.49)	6.05	<0.001	SS and TS	0.70(2.39)	1.05	<0.001
	1.5M and TS	3.39(8.43)	6.25	<0.001	1.5M and TS	−0.74(2.28)	1.17	<0.001
	1.5M and Pre	−17.75(21.46)	14.03	<0.001	1.5M and Pre	1.55(5.21)	1.32	<0.001
Photopic a	FS and Pre	−2.34(15.04)	1.23	<0.001	FS and Pre	0.56(2.18)	0.50	0.004
	SS and Pre	−4.36(19.78)	1.86	<0.001	SS and Pre	1.11(5.04)	0.47	<0.001
	TS and Pre	−5.52(24.99)	2.36	<0.001	TS and Pre	1.57(7.15)	0.65	<0.001
	FS and SS	−1.13(5.05)	2.62	<0.001	FS and SS	0.58(2.68)	0.51	0.001
	SS and TS	−0.83(3.32)	1.90	<0.001	SS and TS	0.24(1.05)	0.36	<0.001
	1.5M and TS	1.08(7.30)	3.36	<0.001	1.5M and TS	−0.57(2.38)	0.87	<0.001
	1.5M and Pre	−4.87(22.70)	2.29	<0.001	1.5M and Pre	1.05(4.72)	0.52	<0.001
Scotopic b	FS and Pre	−10.86(0.87)	5.87	<0.001	FS and Pre	1.78(5.51)	1.80	<0.001
	SS and Pre	−23.55(12.59)	9.83	<0.001	SS and Pre	3.98(5.03)	3.12	<0.001
	TS and Pre	−35.68(18.23)	16.04	<0.001	TS and Pre	5.61(6.96)	4.61	<0.001
	FS and SS	−8.18(3.95)	18.75	<0.001	FS and SS	1.91(2.23)	4.33	<0.001
	SS and TS	−8.45(4.77)	16.33	<0.001	SS and TS	0.99(1.04)	3.84	<0.001
	1.5M and TS	8.99(5.99)	16.37	<0.001	1.5M and TS	−3.60(3.53)	7.46	<0.001
	1.5M and Pre	−24.66(11.21)	17.95	<0.001	1.5M and Pre	3.36(4.11)	2.80	<0.001
Photopic b	FS and Pre	−7.66(12.37)	3.09	<0.001	FS and Pre	0.19(0.64)	0.35	0.049
	SS and Pre	−15.02(15.81)	4.26	<0.001	SS and Pre	0.59(1.41)	0.33	<0.001
	TS and Pre	−21.45(21)	4.32	<0.001	TS and Pre	0.99(2.16)	0.31	<0.001
	FS and SS	−4.23(4.40)	9.00	<0.001	FS and SS	0.20(0.48)	0.51	0.001
	SS and TS	−4.28(3.35)	10.04	<0.001	SS and TS	0.21(0.48)	0.36	<0.001
	1.5M and TS	5.83(10.14)	14.1	<0.001	1.5M and TS	−018(0.38)	0.87	<0.001
	1.5M and Pre	−17.39(18.35)	2.38	<0.001	1.5M and Pre	0.60(1.40)	0.22	<0.001

Note: 1.5M= 6 weeks after final treatment.

Abbreviations: FS, First Session; MD, Mean Difference; SD, Standard deviation; SS, Second Session; TS, Third Session.

Figure 1 Retinal functional changes in D.A 10 ERG test during laser treatment sessions Shown in Root Mean Square (RMS).

Table 3 The Overall Amplitude Changes in Percentage After Each Laser Session and 1.5 Months After Final Treatment Compared to Pretreatment Values

Changes Percentage	Total Mean a-Amplitude Changes	P-value	Total Mean b-Amplitude Changes	P-value	P-value of Comparing a- and b- Amplitude Changes
1 week after F.S	−11.6%	<0.001	−3.7%	<0.001	<0.01
1 week after S.S	−19.1%	<0.001	−13.4%	<0.001	<0.01
1 week after T.S	−25.1%	<0.001	−18.9%	<0.001	<0.01
6 weeks after T.S	−21.4%	<0.001	−14.5%	<0.001	<0.01

Abbreviations: FS, First Session; SS, Second Session; TS, Third Session.

Figure 2 Full-field ERG of a patient enrolled in this study according to ISCEV −2015 standards. The time of ERG recording from baseline (before PRP) to 6 weeks after the final session of PRP has been shown in columns (A–E). Three upper rows are related to dark-adapted states (DA) and 2 lower rows are related to light-adapted states (LA) and between them magnified view of DA 10.0 wave changes of this patient over time have been shown in an ellipsoid inset. As have been shown, a- and b-waves amplitude decrease from baseline to 3ʹrd session after PRP (A–D) and these amplitudes recover and increase 6 weeks after the final session of PRP (E).