Neural Regeneration Research ›› 2024, Vol. 19 ›› Issue (10): 2097-2098.doi: 10.4103/1673-5374.392877

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Exploring the synergy of the eye-brain connection: neuromodulation approaches for neurodegenerative disorders through transcorneal electrical stimulation

Antara Verma, Stephen K. Agadagba, Leanne Lai-Hang Chan*   

  1. Department of Electrical Engineering, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region, China (Verma A, Agadagba SK, Chan LLH) 
    Centre for Eye and Vision Research Ltd., Hong Kong Special Administrative Region, China (Agadagba SK)
    Pennsylvania State University, University Park, PA, USA (Verma A)
  • Online:2024-10-15 Published:2024-01-29
  • Contact: Leanne Lai-Hang Chan, PhD, leanne.chan@cityu.edu.hk.
  • Supported by:
    This work was supported by grants from City University of Hong Kong, China (Project No. SRG-Fd 7005632, SRG-Fd 7005854, and SIRG 7020058) (to LLHC).

Abstract: The connection and interaction between the eye and the brain are crucial to understanding brain disorders (Marchesi et al., 2021). Both the eye and the brain have a limited regenerative capacity as there are few progenitor cells, and nerve cells do not replicate. Hence, neurodegeneration implicates irreversible damage to the central nervous system, as observed in several neurodegenerative diseases (Marchesi et al., 2021). The eye serves as an easily accessible extension of the brain that enables the discovery and non-invasive visualization of possible biomarkers for several neurodegenerative and neurological diseases (London et al., 2013). There has been a recent focus on exploiting the eye-brain connection for therapeutic interventions to treat such diseases. Electrical stimulation remains the oldest and most common method of neuromodulation. However, most forms of electrical stimulation are predominantly invasive (such as deep brain stimulation and motor cortex stimulation) and have numerous postsurgical complications, while other non-invasive forms (such as transcranial electrical stimulation and vagus nerve stimulation) elicit large variability in response to stimulation (Reed and Cohen Kadosh, 2018). Thus, there is a need for novel and more effective non-invasive electrical neuromodulation approaches. In this regard, transcorneal electrical stimulation (TES) is an emerging technique to modulate brain networks in neurodegenerative disorders via non-invasive stimulation of the eye. Electrophysiological, molecular, and behavioral evidence strongly support TES as a neuromodulatory method for brain regions beyond the visual cortex (Yu et al., 2022). This presents a positive outlook for the future of TES and its development as a sought-after neuromodulatory technique. This article provides a summary of the eye-brain connection, highlighting its significance in neurodegenerative diseases. Furthermore, recent advancements in neuromodulation via TES, with an emphasis on electrophysiological evidence, are reported.