Transcorneal electrical stimulation increases chorioretinal blood flow in normal human subjects

Figures & data

Figure 1 Representative images of the chorioretinal blood flow taken by a LSFG instrument with a SBR. A) Before TES. Squares were positioned in three different areas: the rim of the optic disc flanked by two branched vessels crossing the margin of optic disc. This area was selected so that there were no blood vessels. The other two areas were a point midway between the optic disc and macula and the macula area. The macula area was identified by the region without retinal vessels. B) Twenty-four hours after TES. The averaged SBR values within the square for each measurement are indicated below the square. The color map of chorioretinal blood flow shows an increase of blood flow after TES. In all areas, the chorioretinal blood flow was increased, especially in the midway point.

Figure 2 Changes of the mean standardized blur ratio in volunteers with (n = 6) or without (n = 4) TES (mean ± SEM). Dash lines indicate the TES group and solid lines the sham stimulation group. A) In optic disc area, there were no significant differences between the sham stimulation and TES at any times. B) However, for the point located midway between the optic disc and macula, the mean standardized blur ratio was significantly increased at immediate, 3, and 24 h after TES. C) Similarly in the macula area, the mean standardized blur ratio was significantly increased at 3 and 24 h after TES.

Notes: Statistical analysis was performed by two-way repeated measures ANOVA post hoc unpaired t test, *P < 0.05, **P < 0.01. The mean standardized blur ratio was calculated as the ratio of the standardized SBR, which was the ratio of the stimulated eye to the fellow eye, at each measurement point to that of prestimulation at the baseline.

Table 1 Time course of standardized blur ratio after TES in optic disc and macula

Time course (h)
			Pre	Im(0)	0.5	1.0	1.5	2.0	2.5	3.0	24	40
Midway between optic disc and macula	TES	Subject 1	1.00	1.21	0.98	1.05	1.01	1.01	1.01	1.07	1.23	1.05
		Subject 2	1.00	1.40	1.37	1.53	1.46	1.38	1.16	1.82	1.64	1.29
		Subject 3	1.00	0.96	0.88	1.76	1.60	1.64	1.48	1.23	1.53	1.51
		Subject 4	1.00	1.35	1.01	1.18	1.17	1.19	1.15	1.46	1.34	1.25
		Subject 5	1.00	1.10	1.08	1.03	1.14	1.09	1.02	1.21	1.05	0.97
		Subject 6	1.00	1.25	1.91	1.79	1.16	1.35	1.74	1.27	1.59	1.06
		Mean ± SEM		1.21 ± 0.07*	1.21 ± 0.16	1.39 ± 0.14	1.26 ± 0.09	1.28 ± 0.09	1.26 ± 0.12	1.34 ± 0.11*	1.40 ± 0.09**	1.19 ± 0.08
	Sham	Subject 1	1.00	1.01	0.96	1.06	0 99	0.95	0.87	1.06	1.05	1.07
		Subject 2	1.00	0.83	0.75	0.79	0.94	0.92	0.96	0.66	0.84	0.89
		Subject 3	1.00	0.87	1.05	1.18	1.24	1.23	1.25	1.10	0.91	1.21
		Subject 4	1.00	0.98	0.99	1.06	0.98	0.97	0.97	0.95	0.97	0.83
		Mean ± SEM		0.92 ± 0.04	0.94 ± 0.07	1.03 ± 0.08	1.04 ± 0.07	1.02 ± 0.07	1.01 ± 0.08	0.94 ± 0.10	0.94 ± 0.05	1.00 ± 0.09
Optic disc
	TES	Subject 1	1.00	1.45	1.02	0.97	1.04	0.99	1.20	1.22	0.78	1.00
		Subject 2	1.00	1.35	1.39	1.66	1.27	0.97	1.33	1.78	1.43	1.15
		Subject 3	1.00	1.32	1.03	1.12	1.25	1.09	1.27	1.07	0.91	1.04
		Subject 4	1.00	1.24	0.74	0.86	1.17	1.04	1.03	1.05	1.68	1 38
		Subject 5	1.00	1.27	1.45	1.17	1.75	1.16	1.02	0.90	1.59	1.46
		Subject 6	1.00	1.75	2.24	1.58	1.50	1.70	2.18	1.61	1.83	1.20
		Mean ± SEM		1.40 ± 0.08	1.31 ± 0.21	1.23 ± 0.13	1.33 ± 0.10	1.16 ± 0.11	1.34 ± 0.18	1.27 ± 0.14	1.37 ± 0.18	1.20 ± 0.08
	Sham	Subject 1	1.00	1.19	1.38	1.30	1.07	1.05	0.91	1.16	0.91	0.99
		Subject 2	1.00	1.25	1.20	1.11	1.07	0.96	1.03	0.92	0.90	1.08
		Subject 3	1.00	1.06	0.96	1.43	1.72	1.40	1.35	1.19	1.06	1.12
		Subject 4	1.00	1.05	1.10	1.17	0.93	1.02	0.89	0.99	0.79	0.93
		Mean ± SEM		1.14 ± 0.05	1.16 ± 0.09	1.25 ± 0.07	1.12 ± 0.18	1.11 ± 0.10	1.05 ± 0.11	1.07 ± 0.07	0.91 ± 0.05	1.03 ± 0.04
Macula
	TES	Subject 1	1.00	1.30	1.16	1.18	1.07	1.11	1.21	1.21	1.38	1.29
		Subject 2	1.00	1.03	0.92	1.06	1.33	1.14	0.95	1.34	1.40	1.23
		Subject 3	1.00	0.82	1.06	1.21	1.39	1.17	1.15	1.29	1.32	1.94
		Subject 4	1.00	1.40	1.28	1.40	1.62	1.48	1.76	2.07	1.95	1.62
		Subject 5	1.00	1.17	1.61	0.97	1.03	1.04	1.22	1.32	1.76	2.44
		Subject 6	1.00	1.22	1.74	1.41	0.96	1.43	1.59	1.19	1.39	1.04
		Mean ± SEM		1.16 ± 0.09	1.30 ± 0.13	1.20 ± 0.07	1.23 ± 0.10	1.23 ± 0.07	1.31 ± 0.12	1.40 ± 0.14*	1.53 ± 0.11**	1.59 ± 0.21
	Sham	Subject 1	1.00	0.75	0.75	0.81	0.89	0.83	0.71	0.84	0.85	0.96
		Subject 2	1.00	0.98	1.02	0.87	1.05	1.17	1.08	0.84	0.84	1.03
		Subject 3	1.00	0.92	0.96	1.14	1.24	1.37	1.24	1.05	0.97	1.18
		Subject 4	1.00	1.05	1.06	1.05	1.06	1.05	0.79	0.86	0.80	0.95
		Mean ± SEM		0.92 ± 0.06	0.95 ± 0.07	0.97 ± 0.08	1.06 ± 0.07	1.10 ± 0.11	0.96 ± 0.12	0.90 ± 0.05	0.86 ± 0.04	1.03 ± 0.05

Notes: At the point midway between the optic disc and macula and macula area, the standardized blur ratio was significantly increased from 3 h after TES. Two-way repeated measures ANOVA followed by unpaired t-test,

* P < 0.05,

** P < 0.01.

Table 2 Changes of ocular and systemic parameters in the subjects with TES or sham stimulation

Time course (h)
		Pre	Im(0)	0.5	1	1.5	2	2.5	3	24	40
PR (/min)	TES	72 ± 8.3	68 ± 7.2	69 ± 9.0	67 ± 8.9	65 ± 7.3	67 ± 5.5	64 ± 5.6	68 ± 9.6	75 ± 7.3	75 ± 8.3
	Sham	64 ± 13	64 ± 12	60 ± 14	59 ± 7.9	58 ± 6.2	55 ± 3.4	57 ± 9.4	59 ± 9.5	65 ± 7.0	61 ± 12
IOP (mm Hg)	TES	13 ± 2.0	11 ± 1.4	12 ± 1.5	12 ± 1.2	12 ± 1.3	12 ± 1.7	12 ± 2.0	12 ± 2.1	13 ± 1.1	12 ± 1.3
	Sham	14 ± 3.0	15 ± 3.4	16 ± 2.8	14 ± 2.3	14 ± 2.8	14 ± 2.5	15 ± 2.4	14 ± 2.2	14 ± 4.1	14 ± 3.2
MBP (mm Hg)	TES	13 ± 2.0	11 ± 1.4	12 ± 1.5	12 ± 1.2	12 ± 1.3	12 ± 1.7	12 ± 1.9	12 ± 2.1	13 ± 1.1	12 ± 1.3
	Sham	74 ± 7.3	78 ± 6.0	79 ± 5.7	78 ± 12	75 ± 9.1	0 ± 3.1	69 ± 8.4	75 ± 8.1	69 ± 4.3	74 ± 8.0
OPP	TES	36 ± 2.4	34 ± 3.0	34 ± 5.6	32 ± 6.0	30 ± 6.0	36 ± 5.2	39 ± 4.2	31 ± 5.6	35 ± 2.1	37 ± 4.5
	Sham	35 ± 5.2	37 ± 6.3	37 ± 3.4	38 ± 10	36 ± 8.7	39 ± 2.6	30 ± 7.0	36 ± 6.0	32 ± 6.3	35 ± 3.4

Notes: All parameters are not significantly different between prestimulation and each measurement point. The data are the means ± standard deviations.

Abbreviations: MBP, mean blood pressure; OPP, ocular perfusion pressure; PR, pulse rate. TES and sham stimulation group have six and four subjects, respectively. Statistical analyses were performed by two-way repeated measures ANOVA with post hoc test, unpaired Student t-tests.