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Pang JJ. The Variety of Mechanosensitive Ion Channels in Retinal Neurons. Int J Mol Sci 2024; 25:4877. [PMID: 38732096 PMCID: PMC11084373 DOI: 10.3390/ijms25094877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 04/16/2024] [Accepted: 04/20/2024] [Indexed: 05/13/2024] Open
Abstract
Alterations in intraocular and external pressure critically involve the pathogenesis of glaucoma, traumatic retinal injury (TRI), and other retinal disorders, and retinal neurons have been reported to express multiple mechanical-sensitive channels (MSCs) in recent decades. However, the role of MSCs in visual functions and pressure-related retinal conditions has been unclear. This review will focus on the variety and functional significance of the MSCs permeable to K+, Na+, and Ca2+, primarily including the big potassium channel (BK); the two-pore domain potassium channels TRAAK and TREK; Piezo; the epithelial sodium channel (ENaC); and the transient receptor potential channels vanilloid TRPV1, TRPV2, and TRPV4 in retinal photoreceptors, bipolar cells, horizontal cells, amacrine cells, and ganglion cells. Most MSCs do not directly mediate visual signals in vertebrate retinas. On the other hand, some studies have shown that MSCs can open in physiological conditions and regulate the activities of retinal neurons. While these data reasonably predict the crossing of visual and mechanical signals, how retinal light pathways deal with endogenous and exogenous mechanical stimulation is uncertain.
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Affiliation(s)
- Ji-Jie Pang
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX 77030, USA
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2
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Wang J, Wang Y, Guan W, Zhao YE. Full-field electroretinogram recorded with skin electrodes in 6- to 12-year-old children. Doc Ophthalmol 2023; 147:179-188. [PMID: 37530953 PMCID: PMC10638173 DOI: 10.1007/s10633-023-09944-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 07/04/2023] [Indexed: 08/03/2023]
Abstract
PURPOSE To determine the full-field electroretinogram (ffERG) parameters, including the light-adapted (LA) 3 ERG and the photopic negative response (PhNR), in 6- to 12-year-old children. METHODS ffERG data were obtained from 214 eyes of 214 healthy subjects. The amplitudes and peak time of the ffERG responses were obtained from children divided into 6- to 8-year-old and 9- to 12-year-old groups. Using a skin electrode, electrical signals were measured in response to white stimulating light and white background light (LA 3 ERG). A blue background light and red flashes were then used to elicit the PhNR. RESULTS The a-wave amplitude ranged from 0.40 to 9.20 μV, the b-wave ranged from 4.70 to 30.80 μV, and the PhNR ranged from 1.30 to 39.90 μV. The b-wave peak time (33.20 ms) of 6- to 8-year-old groups was slightly shorter than that of the 9- to 12-year-old groups (33.60 ms, P = 0.01), but no differences in amplitudes or in peak time of other components. There were significant correlations between the amplitudes (a-wave and b-wave: r = 0.43, p < 0.001; a-wave and PhNR: r = 0.25, p < 0.001; b-wave and PhNR: r = 0.45, p < 0.001). There was a moderate correlation between the a-wave and b-wave peak time (r = 0.31, P < 0.001). CONCLUSIONS We determined the largest dataset of the LA 3 ERG and PhNR parameters in a population of healthy children, aged 6-12 years, which may provide a useful reference value when evaluating children with potential retinal defects.
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Affiliation(s)
- Jiajun Wang
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
- National Clinical Research Center for Ocular Disease, Wenzhou, Zhejiang, China
| | - Yalan Wang
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
- National Clinical Research Center for Ocular Disease, Wenzhou, Zhejiang, China
| | - Weichen Guan
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
- National Clinical Research Center for Ocular Disease, Wenzhou, Zhejiang, China
| | - Yun-E Zhao
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.
- National Clinical Research Center for Ocular Disease, Wenzhou, Zhejiang, China.
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3
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Lu Z, Zhou M, Guo T, Liang J, Wu W, Gao Q, Li L, Li H, Chai X. An in-silico analysis of retinal electric field distribution induced by different electrode design of trans-corneal electrical stimulation. J Neural Eng 2022; 19. [PMID: 36044887 DOI: 10.1088/1741-2552/ac8e32] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 08/31/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Trans-corneal electrical stimulation (TcES) produces therapeutic effects on many ophthalmic diseases non-invasively. Existing clinical TcES devices use largely variable design of electrode distribution and stimulation parameters. Better understanding of how electrode configuration paradigms and stimulation parameters influence the electric field distribution on the retina, will be beneficial to the design of next-generation TcES devices. APPROACH In this study, we constructed a realistic finite element human head model with fine eyeball structure. Commonly used DTL-Plus and ERG-Jet electrodes were simulated. We then conducted in silico investigations of retina observation surface (ROS) electric field distributions induced by different return electrode configuration paradigms and different stimulus intensities. MAIN RESULTS Our results suggested that the ROS electric field distribution could be modulated by re-designing TcES electrode settings and stimulus parameters. Under far return location (FRL) paradigms, either DTL-Plus or ERG-Jet approach could induce almost identical ROS electric field distribution regardless where the far return was located. However, compared with the ERG-Jet mode, DTL-Plus stimulation induced stronger nasal lateralization. In contrast, ERG-Jet stimulation induced relatively stronger temporal lateralization. The ROS lateralization can be further tweaked by changing the DTL-Plus electrode length. SIGNIFICANCE These results may contribute to the understanding of the characteristics of DTL-Plus and ERG-Jet electrodes based electric field distribution on the retina, providing practical implications for the therapeutic application of TcES.
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Affiliation(s)
- Zhuofan Lu
- School of Biomedical Engineering, Shanghai Jiao Tong University, Address: 800 Dongchuan Road, Minhang District, Shanghai, Shanghai, 200240, CHINA
| | - Meixuan Zhou
- Shanghai Jiao Tong University, Shanghai 200240, Shanghai, 200240, CHINA
| | - Tianruo Guo
- GSBME, University of New South Wales, Graduate School of Biomedical Engineering, University of New South Wales, NSW 2052, Sydney, Australia, Sydney, New South Wales, 2052, AUSTRALIA
| | - Junling Liang
- Shanghai Jiao Tong University, Address: 800 Dongchuan Road, Minhang District, Shanghai Shanghai, CN 200240, Shanghai, 200240, CHINA
| | - Weilei Wu
- Shanghai Jiao Tong University, School of Biomedical Engineering Shanghai Jiao Tong University , Shanghai Jiao Tong University, 800 Dongchuan Road, Minhang District, Shanghai Shanghai, CN 200240, Shanghai, 200240, CHINA
| | - Qi Gao
- Shanghai Jiao Tong University, Address: 800 Dongchuan Road, Minhang District, Shanghai, Shanghai, 200240, CHINA
| | - Liming Li
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, Shanghai, 200240, CHINA
| | - Heng Li
- Shanghai Jiao Tong University, Address: 800 Dongchuan Road, Minhang District, Shanghai Shanghai, CN 200240, Shanghai, 200240, CHINA
| | - Xinyu Chai
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, Shanghai, 200240, CHINA
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4
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Jiang X, Xu Z, Soorma T, Tariq A, Bhatti T, Baneke AJ, Pontikos N, Leo SM, Webster AR, Williams KM, Hammond CJ, Hysi PG, Mahroo OA. Electrical responses from human retinal cone pathways associate with a common genetic polymorphism implicated in myopia. Proc Natl Acad Sci U S A 2022; 119:e2119675119. [PMID: 35594404 PMCID: PMC9173800 DOI: 10.1073/pnas.2119675119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 04/08/2022] [Indexed: 11/25/2022] Open
Abstract
Myopia is the commonest visual impairment. Several genetic loci confer risk, but mechanisms by which they do this are unknown. Retinal signals drive eye growth, and myopia usually results from an excessively long eye. The common variant most strongly associated with myopia is near the GJD2 gene, encoding connexin-36, which forms retinal gap junctions. Light-evoked responses of retinal neurons can be recorded noninvasively as the electroretinogram (ERG). We analyzed these responses from 186 adult twin volunteers who had been genotyped at this locus. Participants underwent detailed ERG recordings incorporating international standard stimuli as well as experimental protocols aiming to separate dark-adapted rod- and cone-driven responses. A mixed linear model was used to explore association between allelic dosage at the locus and international standard ERG parameters after adjustment for age, sex, and family structure. Significant associations were found for parameters of light-adapted, but not dark-adapted, responses. Further investigation of isolated rod- and cone-driven ERGs confirmed associations with cone-driven, but not rod-driven, a-wave amplitudes. Comparison with responses to similar experimental stimuli from a patient with a prior central retinal artery occlusion, and from two patients with selective loss of ON-bipolar cell signals, was consistent with the associated parameters being derived from signals from cone-driven OFF-bipolar cells. Analysis of single-cell transcriptome data revealed strongest GJD2 expression in cone photoreceptors; bipolar cell expression appeared strongest in OFF-bipolar cells and weakest in rod-driven ON-bipolar cells. Our findings support a potential role for altered signaling in cone-driven OFF pathways in myopia development.
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Affiliation(s)
- Xiaofan Jiang
- Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom
- Department of Ophthalmology, King’s College London, London SE1 7EH, United Kingdom
- Department of Twin Research and Genetic Epidemiology, King’s College London, London SE1 7EH, United Kingdom
| | - Zihe Xu
- Department of Ophthalmology, King’s College London, London SE1 7EH, United Kingdom
- Department of Twin Research and Genetic Epidemiology, King’s College London, London SE1 7EH, United Kingdom
| | - Talha Soorma
- Department of Ophthalmology, King’s College London, London SE1 7EH, United Kingdom
| | - Ambreen Tariq
- Department of Ophthalmology, King’s College London, London SE1 7EH, United Kingdom
- Department of Twin Research and Genetic Epidemiology, King’s College London, London SE1 7EH, United Kingdom
| | - Taha Bhatti
- Department of Ophthalmology, King’s College London, London SE1 7EH, United Kingdom
- Department of Twin Research and Genetic Epidemiology, King’s College London, London SE1 7EH, United Kingdom
| | - Alexander J. Baneke
- Department of Ophthalmology, King’s College London, London SE1 7EH, United Kingdom
| | - Nikolas Pontikos
- Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom
| | - Shaun M. Leo
- Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom
- Medical Retina Service, Moorfields Eye Hospital, London EC1V 2PD, United Kingdom
- Inherited Eye Disease Service, Moorfields Eye Hospital, London EC1V 2PD, United Kingdom
| | - Andrew R. Webster
- Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom
- Medical Retina Service, Moorfields Eye Hospital, London EC1V 2PD, United Kingdom
- Inherited Eye Disease Service, Moorfields Eye Hospital, London EC1V 2PD, United Kingdom
| | - Katie M. Williams
- Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom
- Department of Ophthalmology, King’s College London, London SE1 7EH, United Kingdom
- Department of Twin Research and Genetic Epidemiology, King’s College London, London SE1 7EH, United Kingdom
- Medical Retina Service, Moorfields Eye Hospital, London EC1V 2PD, United Kingdom
- Inherited Eye Disease Service, Moorfields Eye Hospital, London EC1V 2PD, United Kingdom
| | - Christopher J. Hammond
- Department of Ophthalmology, King’s College London, London SE1 7EH, United Kingdom
- Department of Twin Research and Genetic Epidemiology, King’s College London, London SE1 7EH, United Kingdom
| | - Pirro G. Hysi
- Department of Ophthalmology, King’s College London, London SE1 7EH, United Kingdom
- Department of Twin Research and Genetic Epidemiology, King’s College London, London SE1 7EH, United Kingdom
| | - Omar A. Mahroo
- Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom
- Department of Ophthalmology, King’s College London, London SE1 7EH, United Kingdom
- Department of Twin Research and Genetic Epidemiology, King’s College London, London SE1 7EH, United Kingdom
- Medical Retina Service, Moorfields Eye Hospital, London EC1V 2PD, United Kingdom
- Inherited Eye Disease Service, Moorfields Eye Hospital, London EC1V 2PD, United Kingdom
- Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, United Kingdom
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5
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Waldie AM, Hobby AE, Chow I, Cornish EE, Indusegaran M, Pekacka A, Nguyen P, Fraser C, Binns AM, Stanford MR, Hammond CJ, McCluskey PJ, Grigg JR, Mahroo OA. Electrophysiological Assessment in Birdshot Chorioretinopathy: Flicker Electroretinograms Recorded With a Handheld Device. Transl Vis Sci Technol 2022; 11:23. [PMID: 35594040 PMCID: PMC9145202 DOI: 10.1167/tvst.11.5.23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 05/03/2022] [Indexed: 11/30/2022] Open
Abstract
Purpose The flicker electroretinogram (ERG) is a sensitive indicator of retinal dysfunction in birdshot chorioretinopathy (BCR). We explored recordings from a handheld device in BCR, comparing these with conventional recordings in the same patients and with handheld ERGs from healthy individuals. Methods Non-mydriatic flicker ERGs, using the handheld RETeval system (LKC Technologies), were recorded with skin electrodes at two centers. At one center (group 1), the stimuli (85 Td·s, 850 Td background) delivered retinal illuminance equivalent to international standards; at the other center (group 2), a different protocol was used (32 Td·s, no background). Patients also underwent international standard flicker ERG recordings with conventional electrodes following mydriasis. Portable ERGs from patients were also compared with those from healthy individuals. Results Thirty-two patients with BCR (mean age ± SD, 56.4 ± 11.3 years) underwent recordings. Portable and standard ERG parameters correlated strongly (r > 0.75, P < 0.01) in both groups. Limits of agreement for peak times were tighter in group 1 (n = 21; -4.3 to +2.0 ms [right eyes], -3.9 to 1.5 ms [left eyes]) than in group 2 (n = 11; -3.4 to +6.9 ms [right eyes], -4.8 to +9.0 ms [left eyes]). Compared with healthy controls (n = 66 and n = 90 for groups 1 and 2, respectively), patients with BCR showed smaller mean amplitudes and longer peak times. Conclusions Portable ERGs correlated strongly with conventional recordings, suggesting potential in rapid assessment of cone system function in office settings. Translational Relevance Flicker ERGs, known to be useful in BCR, can be obtained rapidly with a portable device with skin electrodes and natural pupils.
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Affiliation(s)
- Anna M. Waldie
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
- The Speciality of Ophthalmology Faculty of Medicine and Health University of Sydney, Camperdown, New South Wales, Australia
| | - Angharad E. Hobby
- Section of Ophthalmology, King's College London, London, UK
- Department of Ophthalmology, Guy's and St Thomas’ Hospital NHS Foundation Trust, London, UK
- Division of Optometry and Visual Sciences, City, University of London, London, UK
| | - Isabelle Chow
- Section of Ophthalmology, King's College London, London, UK
- Department of Ophthalmology, Guy's and St Thomas’ Hospital NHS Foundation Trust, London, UK
| | - Elisa E. Cornish
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
- The Speciality of Ophthalmology Faculty of Medicine and Health University of Sydney, Camperdown, New South Wales, Australia
| | - Mathura Indusegaran
- Section of Ophthalmology, King's College London, London, UK
- Department of Ophthalmology, Guy's and St Thomas’ Hospital NHS Foundation Trust, London, UK
| | | | - Phuc Nguyen
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
- The Speciality of Ophthalmology Faculty of Medicine and Health University of Sydney, Camperdown, New South Wales, Australia
| | - Clare Fraser
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
- The Speciality of Ophthalmology Faculty of Medicine and Health University of Sydney, Camperdown, New South Wales, Australia
| | - Alison M. Binns
- Division of Optometry and Visual Sciences, City, University of London, London, UK
| | - Miles R. Stanford
- Section of Ophthalmology, King's College London, London, UK
- Department of Ophthalmology, Guy's and St Thomas’ Hospital NHS Foundation Trust, London, UK
| | - Christopher J. Hammond
- Section of Ophthalmology, King's College London, London, UK
- Department of Ophthalmology, Guy's and St Thomas’ Hospital NHS Foundation Trust, London, UK
| | - Peter J. McCluskey
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
- The Speciality of Ophthalmology Faculty of Medicine and Health University of Sydney, Camperdown, New South Wales, Australia
| | - John R. Grigg
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
- The Speciality of Ophthalmology Faculty of Medicine and Health University of Sydney, Camperdown, New South Wales, Australia
| | - Omar A. Mahroo
- Section of Ophthalmology, King's College London, London, UK
- Department of Ophthalmology, Guy's and St Thomas’ Hospital NHS Foundation Trust, London, UK
- NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK
- Institute of Ophthalmology, University College London, London, UK
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6
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Hanson JVM, Ng MY, Hayward-Koennecke HK, Schippling S, Reeve KA, Gerth-Kahlert C. A three-year longitudinal study of retinal function and structure in patients with multiple sclerosis. Doc Ophthalmol 2021; 144:3-16. [PMID: 34705132 PMCID: PMC8882570 DOI: 10.1007/s10633-021-09855-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 09/15/2021] [Indexed: 11/29/2022]
Abstract
Background Researchers have in recent years begun to investigate ophthalmological manifestations of multiple sclerosis (MS) other than optic neuritis (ON), and it is now clear that changes to retinal function (measured using the electroretinogram, ERG) and structure (measured using optical coherence tomography, OCT) are found in MS patients irrespective of prior ON episodes. ERG results are consistent with dysfunctional bipolar cells, as in other autoimmune diseases. To date, studies have presented only cross-sectional data regarding ERG and OCT. We, therefore, studied the longitudinal course of ERG and OCT in patients with MS, as well as the effect of disability changes and non-ON clinical relapses on these functional and structural measures. Methods MS patients (n = 23) participating in an ongoing longitudinal observational study were invited to take part in a 3-year ophthalmological substudy. ERG and OCT were performed, and measures of MS-related disability and relapse history were obtained. Study visits were repeated annually. ERG peak times, rod b-wave amplitude, mixed rod/cone and cone b-/a-wave amplitude ratios, thickness of the peripapillary retinal nerve fibre layer, and volumes of the segmented retinal layers/complexes were analysed. Using generalised estimating equation models adjusted for age, ON, and MS treatment status, we assessed changes to ERG and OCT over the study duration, the effect of changes in disability and recent non-ON MS relapses on ERG and OCT, and the effect of selected OCT parameters on corresponding ERG parameters. Results At the group level, small fluctuations of several ERG peak times were recorded, with OCT values remaining stable. Increased disability between visits was associated with significant prolongation of mixed rod-cone ERG b-wave peak times. No evidence of associations between OCT and ERG parameters was observed. Conclusions Retinal bipolar cell function may be affected by changes in disability in patients with MS; however, recent non-ON MS clinical relapses appear not to affect ERG or OCT results. As ERG changes in MS patients over 3 years are likely to be small and of uncertain clinical relevance, longitudinal studies of retinal function in MS should be planned over an extended period. Supplementary Information The online version contains supplementary material available at 10.1007/s10633-021-09855-7.
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Affiliation(s)
- James V. M. Hanson
- Department of Ophthalmology, University Hospital Zurich and University of Zurich, Frauenklinikstrasse 24, 8091 Zurich, Switzerland
| | - Mei-Yee Ng
- Masters Program in Biostatistics, University of Zurich, Hirschengraben 84, 8001 Zurich, Switzerland
| | - Helen K. Hayward-Koennecke
- Clinic for Neurology, Neuroimmunology and Multiple Sclerosis Research, University Hospital Zurich and University of Zurich, Frauenklinikstrasse 26, 8091 Zurich, Switzerland
| | - Sven Schippling
- Multimodal Imaging in Neuroimmunological Diseases (MINDS), University Hospital Zurich and University of Zurich, Frauenklinikstrasse 26, 8091 Zurich, Switzerland
| | - Kelly A. Reeve
- Institute for Epidemiology, Biostatistics, and Prevention, Department of Biostatistics, University of Zurich, Hirschengraben 84, 8001 Zurich, Switzerland
| | - Christina Gerth-Kahlert
- Department of Ophthalmology, University Hospital Zurich and University of Zurich, Frauenklinikstrasse 24, 8091 Zurich, Switzerland
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Jiang X, Bhatti T, Tariq A, Williams KM, Chow I, Dar T, Webster AR, Hysi PG, Hammond CJ, Mahroo OA. Prevalence of electronegative electroretinograms in a healthy adult cohort. BMJ Open Ophthalmol 2021; 6:e000751. [PMID: 34368462 PMCID: PMC8291303 DOI: 10.1136/bmjophth-2021-000751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 07/12/2021] [Indexed: 01/08/2023] Open
Abstract
Objective An electronegative electroretinogram (ERG) can indicate important ocular or systemic disease. This study explored the prevalence of electronegative responses to dark-adapted stimuli in a largely healthy cohort. Methods and Analysis 211 participants recruited from the TwinsUK cohort underwent ERG testing incorporating international standard (International Society for Clinical Electrophysiology of Vision (ISCEV)) protocols and additional stimuli. Responses were recorded using conductive fibre electrodes, following pupil dilation and 20 min dark adaptation. Responses analysed were to the ISCEV standard and strong flashes (3.0 and 10 cd/m2 s), and to additional white flashes (0.67–67 cd/m2 s). A-wave and b-wave amplitudes were extracted; b:a ratios were calculated and proportions of eyes with ratios<1 were noted. Results Mean (SD) age was 62.4 (11.4) years (median, 64.3; range 23–86 years). 93% were female. Mean (SD) b:a ratios for right and left eyes, respectively, were 1.86 (0.33) and 1.81 (0.29) for the standard flash, and 1.62 (0.25) and 1.58 (0.23) for the stronger flash; average b:a ratio was lower for the stronger flash (p<0.0001). No waveforms were electronegative. For additional flashes, b:a ratio decreased with increasing flash strength. No electronegative waveforms were seen except in three eyes (0.7%) for the strongest flash; in some cases, drift in the waveform may have artefactually reduced the b:a ratio. Conclusion For standard dark-adapted stimuli, no participants had electronegative waveforms. The findings support the notion that electronegative waveforms (in response to standard flash strengths) are unusual, and should prompt further investigation.
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Affiliation(s)
- Xiaofan Jiang
- Institute of Ophthalmology, University College London, London, UK.,Section of Academic Ophthalmology, School of Life Course Sciences, FoLSM, Kings College London, London, UK.,Department of Twin Research and Genetic Epidemiology, King's College London, London, UK.,NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and the UCL Institute of Ophthalmology, London, UK
| | - Taha Bhatti
- Section of Academic Ophthalmology, School of Life Course Sciences, FoLSM, Kings College London, London, UK.,Department of Twin Research and Genetic Epidemiology, King's College London, London, UK
| | - Ambreen Tariq
- Section of Academic Ophthalmology, School of Life Course Sciences, FoLSM, Kings College London, London, UK.,Department of Twin Research and Genetic Epidemiology, King's College London, London, UK
| | - Katie M Williams
- Section of Academic Ophthalmology, School of Life Course Sciences, FoLSM, Kings College London, London, UK.,Department of Twin Research and Genetic Epidemiology, King's College London, London, UK.,NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and the UCL Institute of Ophthalmology, London, UK
| | - Isabelle Chow
- Section of Academic Ophthalmology, School of Life Course Sciences, FoLSM, Kings College London, London, UK.,Department of Twin Research and Genetic Epidemiology, King's College London, London, UK
| | - Talib Dar
- Section of Academic Ophthalmology, School of Life Course Sciences, FoLSM, Kings College London, London, UK.,Department of Twin Research and Genetic Epidemiology, King's College London, London, UK
| | - Andrew R Webster
- Institute of Ophthalmology, University College London, London, UK.,NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and the UCL Institute of Ophthalmology, London, UK
| | - Pirro G Hysi
- Section of Academic Ophthalmology, School of Life Course Sciences, FoLSM, Kings College London, London, UK.,Department of Twin Research and Genetic Epidemiology, King's College London, London, UK
| | - Christopher J Hammond
- Section of Academic Ophthalmology, School of Life Course Sciences, FoLSM, Kings College London, London, UK.,Department of Twin Research and Genetic Epidemiology, King's College London, London, UK
| | - Omar A Mahroo
- Institute of Ophthalmology, University College London, London, UK.,Section of Academic Ophthalmology, School of Life Course Sciences, FoLSM, Kings College London, London, UK.,Department of Twin Research and Genetic Epidemiology, King's College London, London, UK.,NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and the UCL Institute of Ophthalmology, London, UK.,Physiology, University of Cambridge, Cambridge, UK
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8
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Beneish R, Dorfman AL, Khan A, Polomeno RC, Lachapelle P. Organic visual loss measured by kinetic perimetry and retinal electrophysiology in children with functional amblyopia. Doc Ophthalmol 2021; 143:1-16. [PMID: 33515394 DOI: 10.1007/s10633-020-09811-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 11/30/2020] [Indexed: 11/27/2022]
Abstract
PURPOSE To demonstrate an organic (retinal) amblyogenic defect in functional amblyopes not responding to treatment. METHODS Twenty-four children (Mean age: 5.9 ± 1.8 years; range: 4-10 years) with functional amblyopia were recruited for this study. All these children underwent complete ophthalmic and orthoptic evaluation. In addition, Kinetic Goldman Visual Fields (KGVF), Spectral Domain Optical Coherence Tomography (SD-OCT), full field flash electroretinograms (ffERG) and multifocal electroretinograms (mfERG) were also performed. Ratios were subsequently derived by comparing the amplitudes obtained from the amblyopic eye (AE) to the good eye (GE) for the a- and b-waves of the ffERG, as well as for the ring analysis of the mfERG. RESULTS KGVF showed a central scotoma of varying size (3°-7°) and density (absolute to relative), with increasing target size in 14/24 patients whose best post-treatment vision in the AE ranged from 20/100 to 20/40. The scotoma decreased in size and density with improving vision until a plateau of recovery was reached. The remaining 10/24 patients with a vision ≥ 20/30 showed no scotoma. SD-OCT showed no significant difference between the AE and GE. ffERG and mfERG were obtained in 18/24 patients. The ffERG AE/GE ratio was abnormal in 7 patients, 5 of which had large scotomas on KGVF. The mfERG ring 1 AE/GE ratio was significantly (p < .05) attenuated in 9/18 patients out of which 3 were no longer amblyopic. However, there was no significant difference (p > .05) in ring 1 AE/GE amplitude ratio between those who achieved 20/50-20/40 (.81 ± .26) and those with ≥ 20/25(.86 ± .25). CONCLUSIONS The combined findings of central scotoma on KGVF and mfERG anomalies in patients who did not achieve optimal vision with treatment suggest an underlying organic defect impairing macular function.
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Affiliation(s)
- Raquel Beneish
- Department of Ophthalmology & Visual Sciences, McGill University-Montreal Children's Hospital Research Institute, Montreal, QC, Canada
| | - Allison L Dorfman
- Department of Ophthalmology & Visual Sciences, McGill University-Montreal Children's Hospital Research Institute, Montreal, QC, Canada
- Department of Ophthalmology, Centre Hospitalier Universitaire Sainte-Justine Research Center, Montreal, QC, Canada
| | - Ayesha Khan
- Department of Ophthalmology & Visual Sciences, McGill University-Montreal Children's Hospital Research Institute, Montreal, QC, Canada
| | - Robert C Polomeno
- Department of Ophthalmology & Visual Sciences, McGill University-Montreal Children's Hospital Research Institute, Montreal, QC, Canada
| | - Pierre Lachapelle
- Department of Ophthalmology & Visual Sciences, McGill University-Montreal Children's Hospital Research Institute, Montreal, QC, Canada.
- Research Institute of the McGill University Health Centre, 1001 Decarie Boulevard, Glen Site, Block E, Room EM03238, Montreal, QC, Canada.
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9
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Tu S, Jin Y, Wei J, Pan S, Xiao X, Lin J. Electroretinography (ERG) in the wild giant panda (Ailuropoda melanoleuca). Vet Ophthalmol 2021; 24:216-222. [PMID: 33410590 DOI: 10.1111/vop.12857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 12/13/2020] [Accepted: 12/17/2020] [Indexed: 12/01/2022]
Abstract
PURPOSE Using a quick electroretinography (ERG) protocol for rapid assessment of the retinal function of wild giant pandas (Ailuropoda melanoleuca) performed in field conditions to demonstrate the range of ERG recordings in giant pandas of unknown retinal status. ANIMALS STUDIED Nine free range giant pandas. PROCEDURE All the giant pandas were anesthetized using an intramuscular dexMTZ injection, which is a combination of dexmedetomidine and tiletamine-zolazepam. After 20 mins of dark adaptation, scotopic ERGs were obtained by using three flash intensities: -25 dB (0.0087 cd·s/m2 ), 0 dB (2.75 cd·s/m2 ), and +5 dB (8.7 cd·s/m2 ). Next, photopic ERGs were acquired using a single flash protocol with a flash intensity of 3.0 cd·s/m2 after 10 minutes of light adaptation. RESULTS In scotopic ERG at 0.0087 cd·s/m2 , mean b-wave amplitude and peak time were 82.26 µV (SD ± 16.65 and 95% CI 68.33-96.18) and 66.97 ms (SD ± 10.86 and 95% CI 57.90-76.05), respectively. This flash intensity was below a-wave threshold and resulted in b waves with greater peak times compared to those with higher intensities. At 2.75 cd·s/m2 , the mean a-wave amplitude and peak time were 53.95 µV (SD ± 11.63 and 95% CI 44.23-63.67) and 16.13 ms (SD ± 2.62 and 95% CI 13.94-18.31), and mean b-wave amplitude and peak time were 119.57 µV (SD ± 15.54 and 95% CI 106.57-132.56) and 32.00 ms (SD ± 6.47 and 95% CI 26.59-37.41). At 8.7 cd·s/m2 , the mean a-wave amplitude and peak time were 58.85 µV (SD ± 14.90 and 95% CI 46.39-71.31) and 15.59 ms (SD ± 2.63 and 95% CI 13.40-17.79), and the mean b-wave amplitude and peak time were 132.97 µV (SD ± 22.11 and 95% CI 114.48-151.46) and 32.66 ms (SD ± 6.87 and 95% CI 26.91-38.40). In photopic ERG at 2.75 cd·s/m2 , the mean a-wave amplitude and peak time were 62.08 µV (SD ± 16.61 and 95% CI 48.19-75.97) and 16.28 ms (SD ± 0.90 and 95% CI 15.53-17.03), and the mean b-wave amplitude and peak time were 214.93 µV (SD ± 70.41 and 95% CI 156.07-273.80) and 33.09 ms (SD ± 1.27 and 95% CI 32.03-34.15). CONCLUSION Using a portable ERG system with a brief ERG protocol to perform electroretinographies in wild giant pandas is a practical, useful, and reliable method for the rapid assessment of their retinal function.
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Affiliation(s)
- Shaotong Tu
- College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Yipeng Jin
- College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jiaqi Wei
- College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Shiyue Pan
- College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Xingping Xiao
- College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jiahao Lin
- College of Veterinary Medicine, China Agricultural University, Beijing, China
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10
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Zrenner E, Holder GE, Schiefer U, Wild JM. Quality Control Procedures and Baseline Values for Electroretinography, Perimetry, Color Vision, and Visual Acuity in an International Multicenter Study: Observations from a Safety Trial in Chronic Stable Angina Pectoris. Transl Vis Sci Technol 2020; 9:38. [PMID: 32855884 PMCID: PMC7422805 DOI: 10.1167/tvst.9.8.38] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 02/25/2020] [Indexed: 11/24/2022] Open
Abstract
Purpose To describe quality control procedures and baseline values of electroretinography (ERG), kinetic and static perimetry, color discrimination, and best-corrected visual acuity from a multicenter ocular safety study. Methods A multicenter prospective longitudinal randomized placebo-controlled study was conducted at 11 ophthalmic centers that had received certification following training, instruction, and monitoring. ERGs were obtained with the Espion E2 Ganzfeld console, perimetry with the Octopus 101 perimeter, color discrimination with the Lanthony desaturated D15 test, and best-corrected visual acuity with the Early Treatment Diabetic Retinopathy Study chart. Ophthalmic eligibility required satisfactory outcomes for ERG and perimetry by the second or third pre-inclusion attempts, respectively. Quality control for the ERG was undertaken by two central readers. Results The mean (SD) age of the 97 individuals was 63.5 (7.9) range, 44–83 years. The overall coefficients of variation (CVs) for the ERG peak times were less than those of the only comparable single-center study. The CV for the mean defect of standard automated perimetry was approximately one-third that of the Ocular Hypertension Treatment Study. With increasing age, ERG peak times and color discrimination Total Error Score increased while ERG amplitudes and isopter area all decreased. Conclusions The data illustrate the benefit of identical equipment, stringent on-site instruction and training, quality control, certification, and validation methods. The latter are recommended for planning and conducting multicenter trials using ERG and perimetry to monitor safety and/or efficacy of treatment intervention. Translational Relevance Stringent quality control procedures and reliable reference values are indispensable prerequisites for informative clinical trials.
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Affiliation(s)
- Eberhart Zrenner
- Center for Ophthalmology, University of Tübingen, Tübingen, Germany.,Werner Reichardt Center for Integrative Neuroscience (CIN), University of Tübingen, Tübingen, Germany
| | - Graham E Holder
- Moorfields Eye Hospital, London, UK.,University College London, Institute of Ophthalmology, London, UK
| | - Ulrich Schiefer
- Center for Ophthalmology, University of Tübingen, Tübingen, Germany.,Competence Center Vision Research, University of Applied Sciences Aalen, Aalen, Germany
| | - John M Wild
- College of Biomedical Sciences, Cardiff University, Cardiff, UK
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11
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Pasmanter N, Petersen-Jones SM. A review of electroretinography waveforms and models and their application in the dog. Vet Ophthalmol 2020; 23:418-435. [PMID: 32196872 DOI: 10.1111/vop.12759] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 02/20/2020] [Accepted: 02/24/2020] [Indexed: 02/04/2023]
Abstract
Electroretinography (ERG) is a commonly used technique to study retinal function in both clinical and research ophthalmology. ERG responses can be divided into component waveforms, analysis of which can provide insight into the health and function of different types and populations of retinal cells. In dogs, ERG has been used in the characterization of normal retinal function, as well as the diagnosis of retinal diseases and measuring effects of treatment. While many components of the recorded waveform are similar across species, dogs have several notable features that should be differentiated from the responses in humans and other animals. Additionally, modifications of standard protocols, such as changing flash frequency and stimulus color, and mathematical models of ERG waveforms have been used in studies of human retinal function but have been infrequently applied to visual electrophysiology in dogs. This review provides an overview of the origins and applications of ERG in addition to potential avenues for further characterization of responses in the dog.
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Affiliation(s)
- Nathaniel Pasmanter
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
| | - Simon M Petersen-Jones
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
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12
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Brouwer AH, de Wit GC, de Boer JH, van Genderen MM. Effects of DTL electrode position on the amplitude and implicit time of the electroretinogram. Doc Ophthalmol 2019; 140:201-209. [PMID: 31686287 PMCID: PMC7205847 DOI: 10.1007/s10633-019-09733-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 10/24/2019] [Indexed: 11/24/2022]
Abstract
PURPOSE This study sought to investigate whether there is an optimal position of the Dawson, Trick, and Litzkow (DTL) electrodes when measuring the full-field electroretinogram (ERG) for monitoring purposes. METHODS In 200 uveitis patients, an extended light-adapted (LA) ERG protocol was measured twice, incorporating the International Society for Clinical Electrophysiology of Vision standards. First, a LA ERG was measured with the DTL in the lower lid position (LLP) and thereafter in the fornix position. Differences in amplitudes and implicit times of a-waves, b-waves, and the 30 Hz peak were investigated. Intraclass correlation coefficients (ICCs) as well as coefficients of variation (CoV) were calculated, to assess both reliability and relative variability between the two DTL positions. RESULTS Implicit times showed no statistically significant differences between the two DTL positions. As expected, amplitudes at the different stimulus strengths were 1.12-1.19 higher in the LLP, but there were no significant differences in the CoV between the two DTL positions. The ICC was high for the b-wave and 30 Hz flicker response (0.842-0.979), but lower for the a-wave, especially for amplitudes (0.584-0.716). CONCLUSIONS For monitoring purposes in patients, we conclude that based on relative variability, no position is preferable above the other. However, because in most diseases amplitudes are decreased, the LLP may be chosen because it yields higher amplitudes. Whatever the choice, it is important to ensure that the DTL position remains stable during an ERG recording.
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Affiliation(s)
- Anna H Brouwer
- Bartiméus Diagnostic Centre for Complex Visual Disorders, Zeist, The Netherlands. .,Department of Ophthalmology, University Medical Centre Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
| | - Gerard C de Wit
- Bartiméus Diagnostic Centre for Complex Visual Disorders, Zeist, The Netherlands
| | - Joke H de Boer
- Department of Ophthalmology, University Medical Centre Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands
| | - Maria M van Genderen
- Bartiméus Diagnostic Centre for Complex Visual Disorders, Zeist, The Netherlands.,Department of Ophthalmology, University Medical Centre Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands
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13
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Amorim-de-Sousa A, Moreira L, Macedo-de-Araújo R, Amorim A, Jorge J, Fernandes PR, Queirós A, González-Méijome JM. Impact of contact lens materials on the mfERG response of the human retina. Doc Ophthalmol 2019; 140:103-113. [PMID: 31571070 DOI: 10.1007/s10633-019-09722-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 09/11/2019] [Indexed: 11/29/2022]
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Evaluation of light- and dark-adapted ERGs using a mydriasis-free, portable system: clinical classifications and normative data. Doc Ophthalmol 2018; 137:169-181. [PMID: 30357588 DOI: 10.1007/s10633-018-9660-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Accepted: 10/16/2018] [Indexed: 12/16/2022]
Abstract
PURPOSE The full-field electroretinogram (ff-ERG) is a widely used clinical tool to evaluate generalized retinal function by recording electrical potentials generated by the cells in the retina in response to flash stimuli and requires mydriasis. The purpose of this study was to determine the intra-visit reliability and diagnostic capability of a handheld, mydriasis-free ERG, RETeval (LKC Technologies, Gaithersburg, MD, USA), in comparison with the standard clinical ff-ERG by measuring responses recommended by the International Society for Clinical Electrophysiology of Vision (ISCEV). METHODS This prospective, cross-sectional study included 35 patients recruited at the Hospital for Sick Children (median age = 17, range 11 months-69 years) who had undergone a clinical ff-ERG according to ISCEV standards. For RETeval (n = 35), pupils were undilated in most (n = 29) and sensor strip electrodes were placed under the inferior orbital rim. Stimulus settings on RETeval were equivalent to those used in the clinical ERG. Fifty-seven control participants (median age = 22, range 8-65 years) underwent undilated RETeval ERG to establish standard values for comparison. Patient waveform components with amplitudes < 5th percentile, or implicit times > 95th percentile of normal relative to control data were classified as abnormal for the RETeval system. RESULTS The RETeval system demonstrated a high degree of within-visit reliability for amplitudes (ICC = 0.82) and moderate reliability for implicit times (ICC = 0.53). Cohen's Kappa analysis revealed a substantial level of agreement between the diagnostic capability of RETeval in comparison with clinical ff-ERG (k = 0.82), with a sensitivity and specificity of 1.00 and 0.82, respectively. Pearson's correlations for clinical ERG versus RETeval demonstrated a positive correlation for amplitudes across the rod (r = 0.65) and cone (r = 0.74) ERG waveforms. Bland-Altman plots showed no bias between the mean differences across all amplitude and implicit time parameters of the two systems. CONCLUSIONS The present study demonstrated that RETeval is a reliable tool with reasonable accuracy in comparison with the clinical ERG. The portable nature of RETeval system enables its incorporation at resource-limited centers where the ff-ERG is not readily available. The avoidance of sedation and pupillary dilation are added advantages of RETeval ERG.
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Effect of varying skin surface electrode position on electroretinogram responses recorded using a handheld stimulating and recording system. Doc Ophthalmol 2018; 137:79-86. [PMID: 30046929 PMCID: PMC6153519 DOI: 10.1007/s10633-018-9652-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 07/17/2018] [Indexed: 11/23/2022]
Abstract
Purpose A handheld device (the RETeval system, LKC Technologies) aims to increase the ease of electroretinogram (ERG) recording by using specially designed skin electrodes, rather than corneal electrodes. We explored effects of electrode position on response parameters recorded using this device. Methods Healthy adult twins were recruited from the TwinsUK cohort and underwent recording of light-adapted flicker ERGs (corresponding to international standard stimuli). In Group 1, skin electrodes were placed in a “comfortable” position, which was up to 20 mm below the lid margin. For subsequent participants (Group 2), the electrode was positioned 2 mm from the lid margin as recommended by the manufacturer. Amplitudes and peak times (averaged from both eyes) were compared between groups after age-matching and inclusion of only one twin per pair. Light-adapted flicker and flash ERGs were recorded for an additional 10 healthy subjects in two consecutive recording sessions: in the test eye, electrode position was varied from 2 to 10–20 mm below the lid margin between sessions; in the fellow (control) eye, the electrode was 2 mm below the lid margin throughout. Amplitudes and peak times (test eye normalised to control eye) were compared for the two sessions. Results Including one twin per pair, and age-matching yielded 28 individuals per group. Flicker ERG amplitudes were significantly lower for Group 1 than Group 2 participants (p = 0.0024). However, mean peak times did not differ between groups (p = 0.54). For the subjects in whom electrode position was changed between recording sessions, flash and flicker amplitudes were significantly lower when positioned further from the lid margin (p < 0.005), but peak times were similar (p > 0.5). Conclusions Moving the skin electrodes further from the lid margin significantly reduces response amplitudes, highlighting the importance of consistent electrode positioning. However, this does not significantly affect peak times. Thus, it may be feasible to adopt a more comfortable position in participants who cannot tolerate the recommended position if analysis is restricted to peak time parameters.
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Woo J, Jung S, Gauvin M, Lachapelle P. The DTL ERG electrode comes in different shapes and sizes: Are they all good? Doc Ophthalmol 2017; 135:155-164. [PMID: 28741115 DOI: 10.1007/s10633-017-9600-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 07/03/2017] [Indexed: 11/29/2022]
Abstract
PURPOSE Although the DTL fiber electrode has been in use in the ERG field for more than four decades, its composition was never clearly defined. We compared five different types of conductive (DTL type) yarn (differing in terms of mass, number of filaments, and crimping degree) in order to determine whether we could identify one that would be better suited for the recording of ERGs. METHODS Photopic flash ERGs were recorded from five subjects using the following DTL electrodes: 27/7, 22/1, 11/1, 11/1*2, and 22/1*2. Data analysis included amplitude and peak time measurements of the a- and b-waves in the time domain (TD) as well as measurements of specific frequency descriptors of the ERG waveform in the time-frequency domain using the discrete wavelet transform (DWT) approach. The degree of comfortableness was also assessed in 12 subjects with two surveys (Likert 5-point and the ranking scale). RESULTS Comparisons of TD and DWT parameters did not permit to identify the best DTL electrode, all yielding comparable measures. There was a slight trend for the largest electrode (22/1*2) to yield the largest response, but this was at the expense of comfort, the 22/1*2 electrode being rated as the least comfortable. CONCLUSIONS Given the minimal impact the different electrodes had on the amplitude of the signal, we believe that comfort should dictate our choice. It would appear from our results that use of a multifilament electrode is the best choice since one can get an electrode whose size is optimized for the recording of large responses while minimizing the foreign-body sensation due to the small size of each of the filaments that compose this multifilament electrode.
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Affiliation(s)
- Jungeun Woo
- Departments of Ophthalmology and Neurology and Neurosurgery, Research Institute of the McGill University Health Centre/Montreal Children's Hospital, Montreal, QC, Canada
| | - Suna Jung
- Departments of Ophthalmology and Neurology and Neurosurgery, Research Institute of the McGill University Health Centre/Montreal Children's Hospital, Montreal, QC, Canada
| | - Mathieu Gauvin
- Departments of Ophthalmology and Neurology and Neurosurgery, Research Institute of the McGill University Health Centre/Montreal Children's Hospital, Montreal, QC, Canada
| | - Pierre Lachapelle
- Departments of Ophthalmology and Neurology and Neurosurgery, Research Institute of the McGill University Health Centre/Montreal Children's Hospital, Montreal, QC, Canada. .,Department of Ophthalmology, Research Institute of the McGill University Health Centre, 1001 Decarie Boulevard, Glen Site, Block E, Room EM03238 (Program Mail Drop Point EM03211), Montreal, QC, H4A 3J1, Canada.
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