Red light therapy for eyesight improvement: A short overview

Red light therapy, sometimes referred to as photobiomodulation therapy or PBMT, has attracted significant interest in recent times due to its possible medical advantages, especially in the field of ophthalmology. Here, low-powered red to near-infrared (NIR) light is used in PBMT to activate biological processes.

Conditions where PBMT has shown promise include age-related macular degeneration (AMD), diabetic retinopathy, and other retinal degenerative diseases. PBMT is believed to protect retinal cells from damage, reduce inflammation, and enhance visual performance. Here, we look at the effectiveness, mechanisms of action, and possible side effects of PBMT for eye health.

Mechanisms of action
PBMT works through the absorption of light by cellular photoreceptors ie, cytochrome c oxidase in mitochondria. This absorption triggers a series of biochemical reactions that include improved cellular metabolism, decreased oxidative stress, and increased adenosine triphosphate (ATP) synthesis. These effects are crucial for preserving the health and functionality of cells, especially in tissues that require a lot of energy, like the retina. [AIMS Biophys 2017; 4(3): 337–361]

Neuroprotection
PBMT has demonstrated neuroprotective effects. Studies have shown that it can protect retinal ganglion cells and photoreceptors from degeneration, particularly in conditions like AMD and diabetic retinopathy. This protection is attributed to the therapy’s ability to reduce oxidative stress and promote cellular repair mechanisms. [Int J Ophthalmol 2016;9(1):145–152]

Enhanced mitochondrial function
The primary site of light absorption in mammalian cells has been identified as the mitochondria, and more specifically, cytochrome c oxidase. One hypothesis of how this works is that inhibitory nitric oxide can be dissociated from cytochrome c oxidase thus restoring electron transport and increasing mitochondrial membrane potential. Another likely mechanism is the activation of light or heat-gated ion channels. All these contribute to increased ATP generation. [Photochem Photobiol 2018;94(2):199–212]

Anti-inflammation
PBMT has anti-inflammatory effects, which are beneficial in treating various eye conditions characterized by inflammation. It helps reduce the production of inflammatory cytokines and promotes the release of anti-inflammatory molecules, thereby reducing retinal inflammation and associated damage. [Front Neurosci 2023;17:1150156]

Improved vision
PBMT can improve visual acuity and contrast sensitivity in patients with retinal diseases. This improvement is linked to the therapy’s ability to protect retinal cells and enhance their function. Photoreceptor cells found at the retina are among the most metabolically active cells in the body, both in terms of oxygen consumption and protein production. Thus, improvements in energy production and metabolism will naturally benefit the cells. [Available at https://www.sciencedirect.com/topics/veterinary-science-and-veterinary-medicine/photoreceptor-cell Accessed on 9 July 2024]

Non-invasive
PBMT is a non-invasive treatment and has good safety profile. Unlike other therapies that may involve injections (such as anti-VEGF*) or surgeries, red light therapy can be administered through simple, non-invasive light exposure, reducing the risk of complications and side effects. [Int J Ophthalmol 2016;9(1):145–152]

As with all beneficial treatments, there are potential disadvantages of PBMT. These include:

Variable response
One of the main challenges with PBMT is the variability in patient response. Not all patients experience the same level of benefit, and the reasons for this variability are not fully understood. Factors such as the severity of the condition, the specific wavelength used, and the treatment duration can influence outcomes. Available at https://www.lumitex.com/blog/photobiomodulation-light-tissue-interaction-and-the-current-and-future-states-of-pbm Accessed on 10 July 2024]

Limited long-term data
While short-term studies have shown promising results, there is limited long-term data on the efficacy and safety of PBMT. Long-term studies are needed to understand the sustained effects of the therapy and any potential long-term risks. [OBM Integrative and Complementary Medicine 2022; 7(3): 042; doi:10.21926/obm.icm.2203042] ]

Dosage and protocol optimization
The optimal dosage and treatment protocols for PBMT is yet to be determined. The therapy’s effectiveness depends on factors such as the wavelength of light, intensity, duration of exposure, and frequency of treatment sessions. Further research is needed to establish standardized treatment protocols.

Potential for abuse
There is a potential risk of overuse or inappropriate use. Excessive exposure to light, even at low levels, may potentially lead to adverse effects, such as retinal damage or unwanted cellular changes. It is crucial to follow prescribed treatment guidelines to avoid such risks. [Available at https://ehs.lbl.gov/resource/documents/radiation-protection/non-ionizing-radiation/light-and-infrared-radiation/#:~:text=Prolonged%20exposure%20to%20IR%20radiation,eye%2C%20swelling%2C%20or%20hemorrhaging. Accessed on 10 July 2024]

Accessibility
Access to PBMT may be limited for some patients due to the cost of treatment and availability of specialized equipment. While the therapy is generally considered cost-effective compared to invasive procedures, the initial investment in equipment and ongoing treatment sessions can be a barrier for some patients. [Ed: initial searches returned with results ranging from a few hundred RM to tens of thousands of RM, with little information on their efficacy or safety.]

Conclusion
PBMT offers a promising non-invasive treatment option for various eye conditions, particularly those involving retinal degeneration and inflammation. Its neuroprotective, anti-inflammatory, and mitochondrial-enhancing effects make it a valuable tool in ophthalmology. However, the variability in patient response, limited long-term data, challenges in dosage optimization, potential for overuse, and accessibility issues are important considerations that need to be addressed.

Further research and trials are necessary to fully understand the long-term benefits and risks of PBMT, establish standardized treatment protocols, and ensure its safe and effective use in the field of ophthalmology.