Photobiomodulation: How Light Therapy Could Support the Retina in AMD

What is Photobiomodulation?

Photobiomodulation – PBM for short – refers to the targeted application of light of specific wavelengths to influence biological processes in cells. Unlike phototherapy, which is used in dermatology to treat skin diseases, photobiomodulation does not target the body '''s surface but rather the energy production within the cells themselves. The term was introduced in 2014 by an international panel of experts as the standard designation to replace older and sometimes misleading terms like “Low-Level Laser Therapy” (LLLT) or “cold laser therapy”.

The basic principle of photobiomodulation has been the subject of scientific research for several decades. As early as the 1960s, scientists observed that low-intensity light can exert biological effects on tissue without heating or damaging it. Since then, an extensive field of research has developed, which today includes applications in wound healing, pain therapy, neurology, and – increasingly – in ophthalmology. Photobiomodulation in the eye is a relatively young research area that has gained considerable momentum over the past ten years.

The Mechanism of Action: From Light to Cellular Energy

To understand how PBM works, we need to take a look inside our cells, specifically at the mitochondria. These “powerhouses of the cells” are responsible for producing adenosine triphosphate (ATP), the universal energy currency of the body. A key enzyme in this process is cytochrome c oxidase.

This is where light comes into play. Research has shown that light in the red to near-infrared spectrum, particularly at a wavelength of 670 nanometers (nm), is absorbed by cytochrome c oxidase. This absorption appears to boost the enzyme’s activity, leading to increased ATP production. The result is more available energy for the cell, which can help maintain its function and support repair processes. For the retina, which has one of the highest energy demands in the body, this effect is of particular interest.

"PBM with 670 nm light can increase the activity of cytochrome c oxidase and thus improve the energy supply to retinal cells."

PBM and Laser – An Important Distinction

The term “light therapy” often brings to mind laser treatments. However, PBM is fundamentally different from the high-energy laser therapies used, for example, to treat retinal tears or diabetic retinopathy. While therapeutic lasers work by generating heat to deliberately create scars (photocoagulation), PBM uses non-thermal light of low intensity.

The light intensity in PBM is so low that it does not cause any thermal damage to the tissue. The effect is purely biological and is based on the stimulation of cellular processes – hence the term “biomodulation.” This non-invasive and gentle approach is a key feature of photobiomodulation and a prerequisite for its use on the sensitive retina.

Why the Eye Specifically?

The retina is one of the most metabolically active tissues in the human body. This high energy demand makes it particularly susceptible to age-related changes and oxidative stress, which play a central role in the development of AMD. A decline in mitochondrial function and reduced ATP production are considered key factors in the aging process of the retina.

PBM directly addresses this point by aiming to improve the energy balance in retinal cells. Furthermore, studies suggest that PBM may have anti-inflammatory effects and reduce the formation of drusen, the characteristic deposits in AMD. The eye’s optical transparency also allows the light to reach the retina with minimal scattering, making it an ideal target organ for this form of therapy.

Current Evidence: What the Studies Show

The clinical evidence for PBM in dry AMD is primarily based on the LIGHTSITE study series. The LIGHTSITE III study, a multicenter, randomized, sham-controlled trial, is particularly significant. Over 100 patients with dry AMD were treated with the Valeda Light Delivery System (LumiThera) over a period of 13 months.

The results, published in the journal Retina in 2024, showed a statistically significant improvement in visual acuity in the treatment group compared to the sham (placebo) group. On average, patients in the PBM group gained 5.5 letters on the eye chart, while the control group’s vision remained largely unchanged. Furthermore, there was a reduction in the volume of drusen in the treated eyes.

Safety Profile and Tolerability

The LIGHTSITE studies also provided important insights into the safety of PBM. The treatment was generally well-tolerated, with no serious device-related side effects reported. The most common side effects were temporary and mild, such as dry eyes or a feeling of being dazzled immediately after the light application.

One aspect discussed in the scientific literature is a slightly increased rate of conversion to wet AMD observed in the treatment group compared to the placebo group in the LIGHTSITE III study. The study authors note that this finding requires further investigation and may be due to chance effects. Nevertheless, it underscores the importance of regular ophthalmological check-ups during and after PBM treatment.

A 2024 study by Borrelli and colleagues confirmed the good tolerability of PBM with another device system (EYE-LIGHT). The authors concluded that photobiomodulation is safe and well-tolerated in patients with dry AMD. Overall, the available data suggest that PBM has a favorable safety profile – however, regular ophthalmological monitoring remains essential.

FDA Approval: A Milestone

In January 2025, the U.S. Food and Drug Administration (FDA) granted De Novo classification for the Valeda Light Delivery System from LumiThera for the treatment of dry AMD with geographic atrophy. This decision marked a significant milestone in the history of photobiomodulation: for the first time, a PBM device was approved by a major regulatory authority for use in an eye disease.

The De Novo classification means that the FDA considered the device to be novel – there was no comparable product category before. The approval was based on data from the LIGHTSITE study series and covers its use under the supervision of an ophthalmologist. It is important to emphasize that this approval is specific to the Valeda system and its application in an ophthalmology practice – it is not automatically transferable to other PBM devices or forms of application.

Separate regulatory requirements apply to the European market. In Germany and the EU, CE marking as a medical device is required. The ongoing MACULIGHT study will, among other things, help to expand the database for a possible European approval. Until then, photobiomodulation for AMD in Germany is accessible through clinical trials.

Outlook and Importance for Patients

Photobiomodulation is at an exciting point in its development. The study results to date are encouraging, the FDA approval in the US is a strong signal, and research is also being advanced in Germany with the MACULIGHT study. At the same time, further studies are needed to better understand long-term effects, optimal treatment protocols, and suitability for different stages of AMD.

For patients with dry AMD, photobiomodulation is particularly interesting because it represents a fundamentally new therapeutic approach. While nutritional supplements based on the AREDS2 formula and lifestyle changes continue to form the basis of personal preventive care, PBM could serve as a complementary measure to support the cellular energy supply of the retina. The combination of different approaches – a healthy diet, smoking cessation, UV protection, regular check-ups, and possibly photobiomodulation – reflects the modern understanding of AMD as a multifactorial disease that also requires a multimodal treatment strategy.

If you would like to learn more about photobiomodulation for dry AMD, you can find further information, an interactive graphic on the mechanism of action, and an overview of the current study situation on our topic page on photobiomodulation. Also, talk to your ophthalmologist about whether photobiomodulation might be an option for your individual situation.