Near infrared/ red light therapy a potential countermeasure for mitochondrial dysfunction in spaceflight associated neuro-ocular syndrome (SANS)

Ethan Waisberg, Joshua Ong, Mouayad Masalkhi & Andrew G. Lee

Introduction:Spaceflight-associated neuro-ocular syndrome (SANS) is a syndrome know to affect a significant proportion of astronauts during long-duration spaceflight (LDSF). SANS is characterized by optic disc edema [1], hyperopic shifts [2], chorioretinal folds [3] and globe flattening [4]. While the precise etiology of SANS remains incompletely understood, it is hypothesized to be as a result of the unique conditions encountered in the microgravity environment characteristic of LDSF, and heightened radiation exposure [5]. So far, SANS has been associated with alterations in fluid distribution and ocular structural adaptations induced by microgravity conditions [5].

Key points:

• Red/Near Infrared (NIR) Light Therapy may serve as a non-invasive and side-effect-free countermeasure to improve mitochondrial function during LDSF.
• NIR/red light therapy is a form of phototherapy that utilizes specific wavelengths of light to promote healing and reduce inflammation [15, 16].
• NIR/red light therapy is believed to enhance mitochondrial function via the absorption of photons by mitochondrial chromophores, such as cytochrome c oxidase, contributing to improved cellular respiration and ATP production, and reducing ROS generation [17].
• NIR/red light also has known anti-inflammatory properties, which could mitigate inflammation associated with SANS and its impact on ocular tissues [17].
• Furthermore, secondary effects can also occur hours following NIR/red light exposure including the dissociation of nitric oxide from its binding site, modification of the ATP pool and an increased mitochondrial intermembrane potential (Fig. 1) [18].
• Alterations in ATP levels can affect cyclic adenosine monophosphate levels, intracellular calcium levels and cellular metabolism.