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Tuna AR, Pinto N, Fernandes A, Brardo FM, Pato MV. Can repetitive transcranial magnetic stimulation influence the visual cortex of adults with amblyopia? - systematic review. Clin Exp Optom 2024; 107:691-697. [PMID: 39025787 DOI: 10.1080/08164622.2024.2363369] [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: 10/25/2023] [Revised: 04/24/2024] [Accepted: 05/02/2024] [Indexed: 07/20/2024] Open
Abstract
Amblyopia is the most frequent cause of monocular vision loss. Transcranial Magnetic Stimulation (TMS) has been used to improve several vision parameters of the amblyopic eye in adulthood. This study is relevant in order to evaluate TMS effects and to raise awareness of the need for further research. Transcranial Magnetic Stimulation (TMS) is a neuromodulation technique capable of changing cortical excitability. In the last decade, it has been used to improve visual parameters in amblyopic patients. The main goal of this systematic review is to evaluate the influence of TMS in the amblyopic eye, in the visual parameters of amblyopic patients. Searches were done in PubMed and Embase databases, and a combined search strategy was performed using the following Mesh, EMBASE, and keywords: 'Amblyopia', 'Transcranial Magnetic Stimulation', and 'theta burst stimulation'. This review included randomised controlled studies, descriptive cases, and clinical case studies with adult amblyopes. All articles that had any of the following characteristics were excluded: children or animal studies, reviews, pathologies other than amblyopia, and other techniques rather than repetitive TMS (rTMS), or Theta Burst Stimulation (TBS). A total of 42 articles were found, of which only four studies (46 amblyopes) meet the criteria above. Three of the articles found significant improvement after one session of continuous TBS (cTBS) in visual parameters like visual acuity, contrast sensitivity, suppressive imbalance, and stereoacuity. One study found a significant visual improvement with 10 Hz rTMS. Only one stimulation-related dropout was reported. The few existing studies found in this review seem to show that through the usage of high-frequency rTMS and cTBS, it is possible to re-balance the eyes of an adult amblyope. However, despite the promising results, further research with larger randomised double-blind studies is needed for a better understanding of this process.
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Affiliation(s)
- Ana Rita Tuna
- Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal
- GRUBI - Systematic Reviews Group, University of Beira Interior, Covilhã, Portugal
| | - Nuno Pinto
- Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal
- GRUBI - Systematic Reviews Group, University of Beira Interior, Covilhã, Portugal
| | - Andresa Fernandes
- Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal
- GRUBI - Systematic Reviews Group, University of Beira Interior, Covilhã, Portugal
- Department of Physics, University of Beira Interior, Covilhã, Portugal
| | - Francisco Miguel Brardo
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal
- GRUBI - Systematic Reviews Group, University of Beira Interior, Covilhã, Portugal
- Department of Physics, University of Beira Interior, Covilhã, Portugal
| | - Maria Vaz Pato
- Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal
- GRUBI - Systematic Reviews Group, University of Beira Interior, Covilhã, Portugal
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Tuna AR, Pinto N, Fernandes A, Brardo FM, Vaz Pato M. Longstanding effects of continuous theta burst stimulation in adult amblyopes. Clin Exp Optom 2024; 107:457-464. [PMID: 37400360 DOI: 10.1080/08164622.2023.2228989] [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: 03/02/2023] [Revised: 06/02/2023] [Accepted: 06/16/2023] [Indexed: 07/05/2023] Open
Abstract
CLINICAL RELEVANCE Continuous theta burst stimulation may be an important tool in the therapeutic management of amblyopia, when trying to correct the established neuronal imbalance. It is important to understand whether two sessions of continuous theta burst stimulation produce greater and longstanding changes in visual acuity and suppressive imbalance than one session of continuous theta burst stimulation. BACKGROUND We hypothesise that through the usage of continuous theta burst stimulation (cTBS) it is possible to change cortical excitability in a situation where visual impairment is present. METHODS We selected 22 adult amblyopes, 18 females and 4 males, with an age range of 20-59 years. They were randomised into two groups: group A with 10 amblyopes was submitted to one session of cTBS and group B with 12 amblyopes submitted to two sessions of cTBS. Visual acuity (VA) and suppressive imbalance (SI) were evaluated immediately before and after stimulation in both groups A and B. A follow-up was done in both groups. RESULTS For both group A and B, the VA improvements were significant after cTBS (p = 0.005 and p = 0.003, respectively). Regarding SI, both group A and B had significant improvements after cTBS (p = 0.03 and p = 0.005, respectively). Comparing groups, A and B no significant differences were found with regard to the results obtained both for VA (p = 0.72) and SI (p = 0.24). However, significant differences were found between group A and B with regard to the duration of stimulation effect for VA (p = 0.049) and SI (p = 0.03). CONCLUSION We conclude that two sessions of cTBS do not produce better results than one session of stimulation. However, it seems that two sessions of cTBS produce longstanding effects in VA and SI.
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Affiliation(s)
- Ana Rita Tuna
- CICS - Health Sciences Research Centre, Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal
| | - Nuno Pinto
- CICS - Health Sciences Research Centre, Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal
| | - Andresa Fernandes
- CICS - Health Sciences Research Centre, Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal
- Department of Physics, University of Beira Interior, Covilhã, Portugal
| | - Francisco Miguel Brardo
- CICS - Health Sciences Research Centre, Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal
- Department of Physics, University of Beira Interior, Covilhã, Portugal
| | - Maria Vaz Pato
- CICS - Health Sciences Research Centre, Faculty of Health Sciences, University of Beira Interior, Covilhã, Portugal
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Wang J, Song F, He X, Bao M. Negligible contribution of adaptation of ocular opponency neurons to the effect of short-term monocular deprivation. Front Psychol 2024; 14:1282113. [PMID: 38274682 PMCID: PMC10809396 DOI: 10.3389/fpsyg.2023.1282113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 12/21/2023] [Indexed: 01/27/2024] Open
Abstract
Introduction Modeling work on binocular rivalry has described how ocular opponency neurons represent interocular conflict. These neurons have recently been considered to mediate an ocular dominance shift to the eye that has viewed a backward movie for long during which time the other eye is presented with a regular movie. Unlike typical short-term monocular deprivation, the visual inputs are comparable across eyes in that "dichoptic-backward-movie" paradigm. Therefore, it remains unclear whether the ocular opponency neurons are also responsible for the short-term monocular deprivation effect which is prevalently explained by the homeostatic compensation theory. We designed two experiments from distinct perspectives to investigate this question. Methods In Experiment 1, we mitigated the imbalance in the activity of opponency neurons between the two eyes during monocular deprivation by presenting video stimuli alternately. In Experiment 2, we directly evaluated the response of opponency neurons before and after monocular deprivation using SSVEP techniques. Results Consistent with each other, both experiments failed to provide reliable evidence supporting the involvement of ocular opponency neurons in the short-term monocular deprivation effect. Discussion Our results suggest that ocular opponency neurons may not play an essential role in the short-term monocular deprivation effect, potentially due to interference from the homeostatic plasticity mechanism.
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Affiliation(s)
- Jue Wang
- CAS Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
- Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Fangxing Song
- CAS Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
- Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Xin He
- CAS Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
| | - Min Bao
- CAS Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
- Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Brain and Cognitive Science, Beijing, China
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