Vishal Biswas, M. Optom.
Assistant Professor, Noida International University, Greater Noida, India
Photobiomodulation (PBM), also referred to as low-level laser therapy, is developing as a transformative treatment approach, especially in the management of retinal disorders. (1,2) This non-invasive method utilises light in the red to near-infrared spectrum to activate cellular activities and has demonstrated potential in decelerating disease development, promoting cellular repair, and increasing visual results. As researchers persist in elucidating the basic mechanisms behind PBM, its applicability in the treatment of diverse retinal disorders, such as Age-Related Macular Degeneration (AMD), Diabetic Retinopathy, and Retinopathy of Prematurity, is becoming increasingly persuasive.
The Mechanisms of Photobiomodulation
At the core of the therapeutic effect of PBM is its ability to stimulate mitochondrial activity. The primary target for PBM is cytochrome c oxidase (CCO), a key enzyme in the mitochondrial electron transport chain. When exposed to specific wavelengths of light, CCO becomes activated, leading to increased Adenosine Triphosphate (ATP) production, reduction of Reactive Oxygen Species (ROS), and improved blood flow to the affected tissues. (3) This mitochondrial stimulation is critical because retinal cells, particularly photoreceptors and ganglion cells, are highly dependent on adequate energy supply and are vulnerable to oxidative stress and inflammation.
Figure 1: Mechanism of Action of Red/Near-Red Light on Cellular Processes
Clinical Efficacy in Retinal Diseases
Age-Related Macular Degeneration
Age-Related Macular Degeneration (AMD) is one of the leading causes of vision loss worldwide. Several studies have suggested that PBM can effectively reduce drusen volume, improve visual acuity, and enhance contrast sensitivity in patients with dry AMD. (4) In a clinical trial involving 348 eyes, PBM treatment led to a significant improvement in visual outcomes, with 94.5% of patients experiencing improved visual acuity. (5) Additionally, the LIGHTSITE II study demonstrated that PBM can offer therapeutic benefits over a longer follow-up, underscoring its potential as a viable treatment option. (5)
Diabetic Retinopathy
This condition is characterised by progressive retinal damage due to diabetes and is a leading cause of blindness in adults. Research indicates that PBM may mitigate the effects of Diabetic Retinopathy by improving retinal cell metabolism, reducing inflammation, and promoting healing. (6) For instance, PBM has been shown to decrease retinal thickness and enhance visual function in patients with non-centre involving Diabetic Macular Oedema. (6) Furthermore, studies on animal models of diabetes have shown that PBM treatment results in reduced apoptosis and improved retinal health metrics. (3)
Retinopathy of Prematurity
Retinopathy of Prematurity (ROP) is a condition affecting premature infants that can lead to blindness. Initial research suggests that PBM may help reduce retinal damage caused by oxygen toxicity, making it a potential preventative therapy for infants at risk. (7) In experimental models, PBM application reduced the inflammatory response and protected developing retinal cells from damage. (7)
Limitations and Challenges
The widespread adoption of PBM for retinal diseases faces challenges such as variability in treatment protocols, varying evidence quality, and small sample sizes, necessitating larger, well-designed trials. (3)
Conclusion
Photobiomodulation is a promising approach to treating retinal diseases, enhancing health and visual function.
However, further research is needed to optimise protocols and confirm their long-term efficacy and safety.
This innovative approach demonstrates the potential of light for healing and vision restoration.
References
- Chichan H, Aldujaly IH, Michalakis K, Kanal L. Photobiomodulation in ocular therapy: current status and future perspectives. Int J Ophthalmol. 2025 Feb 18;18(2):351-357.
- Garg D, Daigavane S. Photobiomodulation in Ophthalmology: A Comprehensive Review of Bench-to-Bedside Research and Clinical Integration. Cureus. 2024 Sep 18;16(9).)
- Huang YY, et al. Mitochondrial Dysfunction in Age-Related Macular Degeneration: A Possible Role for Photobiomodulation. Photomed Laser Surg. 2020;38(6):315–22.).
- Merry GF, Munk MR, Dotson RS, Walker MG, Devenyi RG. Photobiomodulation Reduces Drusen Volume and Improves Visual Acuity and Contrast Sensitivity in Dry Age-Related Macular Degeneration. Acta Ophthalmol. 2017;95(4):e270–7
- Burton B, Parodi MB, Jürgens I, et al. LIGHTSITE II: Evaluation of Multiwavelength Photobiomodulation in Non-exudative Age-Related Macular Degeneration. Ophthalmol Ther. 2023;12(2):953–68
- Tang J, Herda AA, Kern TS. Photobiomodulation in the Treatment of Patients with Non-Center-Involving Diabetic Macular Edema. Br J Ophthalmol. 2014;98:1013–5
- Kent AL, et al. A Pilot Randomised Clinical Trial of 670 nm Red Light for Reducing Retinopathy of Prematurity. Pediatr Res. 2020;87:131–6