Clinical Usefulness of Fresnel Ganzfeld Stimulator

Jung Woo Han; Yoon Jin Kong; Tae Kwann Park; Young Hoon Ohn

doi:10.3341/jkos.2015.56.12.1874

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Han, Kong, Park, and Ohn: Clinical Usefulness of Fresnel Ganzfeld Stimulator

Original Article

J Korean Ophthalmol Soc 2015;56(12):1874-1879.

Published online: 29 August 2015

DOI: https://doi.org/10.3341/jkos.2015.56.12.1874

Clinical Usefulness of Fresnel Ganzfeld Stimulator

Jung Woo Han, M.D, Yoon Jin Kong, M.D, Tae Kwann Park, M.D, Young Hoon Ohn, M.D, PhD

Department of Ophthalmology, Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea

Address reprint requests to Young Hoon Ohn, MD, PhD Department of Ophthalmology, Soonchunhyang University Bucheon Hospital, #170 Jomaru-ro, Wonmi-gu, Bucheon 14584, Korea Tel: 82-32-621-5425, Fax: 82-32-621-5435 E-mail: yhohn@schmc.ac.kr

Received 15 May 201524 July 2015 Accepted 25 September 2015

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

To compare electroretinogram (ERG) waveforms acquired using a ganzfeld stimulator and a Fresnel ganzfeld stimulator.

Methods

ERGs were recorded with a ganzfeld stimulator and a Fresnel ganzfeld stimulator from both eyes of 25 volunteers. Peak-to-trough amplitudes and peak implicit times were compared between both eyes and between a ganzfeld stimulator and a Fresnel ganzfeld stimulator. ERGs taken from the sitting and supine positions were also compared using the Fresnel ganzfeld stimulator.

Results

There was no statistically significant difference between the Fresnel ganzfeld stimulator and dome-shaped ganzfeld stimulator in amplitude and implicit time of dark adapted 0.01, 3.0 ERG, photopic 3.0 ERG, photopic 3.0 flicker. The differences in amplitude and implicit time between the right and left eyes were not influenced by the Fresnel ganzfeld stimulator. Additionally, no differences were observed in ERGs obtained from the sitting and supine positions using the Fresnel ganzfeld stimulator.

Conclusions

The newly developed ganzfeld stimulator with a sealed Fresnel lens can be considered as a reliable alternative method for measuring ERGs. Fresnel ganzfeld stimulator is useful for patients having problems with mobility or uncooperative children.

Keywords: Electroretinogram (ERG), Fresnel lens, Ganzfeld stimulator

References

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Figure 1.

The traditional dome-shaped ganzfeld stimulator. (A) Front (B) Side.

Figure 2.

The shape of Fresnel lens. Fresnel lens is made by removing the non-refractive part of a conventional lens, leaving the lens with a thin profile. (A) Side. (B) Front.

Figure 3.

Comparision of dome-shaped ganzfeld stimulator and Fresnel ganzfeld stimulator. (A) Conventional ganzfeld. (B) Fresnel ganzfeld.

Figure 4.

Fresnel ganzfeld stimulator. Its lightweight construction, built-in infra-red video display, and stimulus trigger make it an ideal handheld stimulator for the reclining or supine subject. (A) Front side. (B) Back side. (C) Supine position.

Table 1.

Comparison of b-wave amplitude and the implicit time of each response using Fresnel ganzfeld stimulator between the right and left eye (n = 25)

Parameter	Right mean	Left mean	p-value^*
Amplitude (μ V)
Dark adapted 0.01 ERG	116.25 ± 28.76	115.83 ± 35.29	0.928
Dark adapted 3.0 ERG	255.65 ± 42.90	253.78 ± 43.63	0.897
Photopic 3.0 ERG	69.99 ± 12.16	73.37 ± 10.23	0.342
30 Hz flicker	45.35 ± 13.70	44.09 ± 15.06	0.797
Implicit time (msec)
Dark adapted 0.01 ERG	100.03 ± 7.73	100.93 ± 8.44	0.330
Dark adapted 3.0 ERG	49.35 ± 2.65	49.50 ± 2.59	0.877
Photopic 3.0 ERG	28.11 ± 1.63	28.43 ± 1.53	0.494
30 Hz flicker	25.31 ± 1.64	25.29 ± 1.67	0.971

Values are presented as mean ± SD unless otherwise indicated. ERG = electroretinogram.^* p-value by paired t-test.

Table 2.

Comparison of a-wave amplitude and the implicit time of each response between Ganzfeld stimulator and Fresnel ganzfeld stimulator (n = 25)

Parameter	Ganzfeld mean	Fresnel ganzfeld mean	p-value^*
Amplitude (μ V)
Dark adapted 3.0 ERG	139.41 ± 89.99	140.80 ± 86.69	0.900
Photopic 3.0 ERG	50.50 ± 3.46	54.30 ± 2.40	0.239
Implicit time (msec)
Dark adapted 3.0 ERG	22.37 ± 1.96	22.16 ± 2.11	0.549
Photopic 3.0 ERG	16.10 ± 2.28	16.38 ± 2.75	0.288

Values are presented as mean ± SD unless otherwise indicated. ERG = electroretinogram.^* p-value by paired t-test.

Table 3.

Comparison of b-wave amplitude and the implicit time of each response between Ganzfeld stimulator and Fresnel ganzfeld stimulator (n = 25)

Parameter	Ganzfeld mean	Fresnel ganzfeld mean	p-value^*
Amplitude (μ V)
Dark adapted 0.01 ERG	119.42 ± 31.58	116.04 ± 31.78	0.274
Dark adapted 3.0 ERG	256.17 ± 44.54	254.71 ± 42.72	0.074
Photopic 3.0 ERG	72.47 ± 11.53	71.68 ± 11.22	0.248
30 Hz flicker	46.82 ± 13.31	45.35 ± 13.71	0.062
Implicit time (msec)
Dark adapted 0.01 ERG	99.50 ± 7.62	100.46 ± 8.01	0.212
Dark adapted 3.0 ERG	49.01 ± 2.67	49.43 ± 2.59	0.501
Photopic 3.0 ERG	28.38 ± 1.48	28.27 ± 1.57	0.183
30 Hz flicker	25.79 ± 2.41	25.30 ± 1.63	0.138

Values are presented as mean ± SD unless otherwise indicated. ERG = electroretinogram.^* p-value by paired t-test.

Table 4.

Comparison of b-wave amplitude and the implicit time of each response using Fresnel ganzfeld stimulator between sitting and supine position (n = 25)

Parameter	Sitting mean	Supine mean	p-value^*
Amplitude (μ V)
Dark adapted 0.01 ERG	114.17 ± 27.16	109.91 ± 18.95	0.551
Dark adapted 3.0 ERG	257.40 ± 48.07	262.52 ± 43.63	0.714
Photopic 3.0 ERG	71.60 ± 10.97	67.13 ± 10.70	0.211
30 Hz flicker	50.65 ± 15.21	46.20 ± 15.64	0.398
Implicit time (msec)
Dark adapted 0.01 ERG	101.63 ± 6.70	101.20 ± 7.88	0.842
Dark adapted 3.0 ERG	49.68 ± 3.49	50.33 ± 3.23	0.529
Photopic 3.0 ERG	28.98 ± 1.78	28.08 ± 1.57	0.076
30 Hz flicker	24.79 ± 0.61	25.40 ± 1.63	0.134

Values are presented as mean ± SD unless otherwise indicated. ERG = electroretinogram.^* p-value by paired t-test.

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