Light Therapy for Chronic Pain

Overseen By Matthew C Mauck, MD, PhD

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: University of North Carolina, Chapel Hill

Disqualifiers: Vision disorders, Color blindness, Pregnancy, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 5

Duration: 1 week

60 Participants Needed

Trial Summary

What is the purpose of this trial?

Participants with chronic pain conditions including chronic low back pain and fibromyalgia may benefit from light stimuli presented to the retina to reduce chronic pain severity and pain sensitivity. Participants will be recruited into this study and will be presented with one of three uniform light stimuli via a wide-field ganzfeld in three conditions to determine the retinal mechanisms that reduce pain. This work will lead to a greater understanding of retinal mechanisms that contribute to pain and will assist the design of future studies to harness the potential of light based pain therapies.

Will I have to stop taking my current medications?

The trial information does not specify whether you need to stop taking your current medications. It might be best to discuss this with the study team or your doctor.

What data supports the effectiveness of this treatment for chronic pain?

Research shows that green light exposure can reduce pain intensity in conditions like migraines and fibromyalgia, and a study found that visual stimulation can increase pain tolerance. Additionally, a clinical trial demonstrated that green and violet laser therapy significantly decreased pain scores in chronic neck and shoulder pain. ^{1 2 3 4 5}

Is light therapy safe for humans?

Bright light therapy, used for conditions like seasonal affective disorder, can potentially harm the eyes if the light source emits damaging wavelengths. Safety measures include using lamps without harmful emissions and regular eye check-ups, especially for those with existing eye conditions. ^{6 7 8 9 10}

How does light therapy for chronic pain differ from other treatments?

Light therapy for chronic pain is unique because it uses specific colors of light, like green light, to reduce pain through the visual system, potentially increasing natural pain-relieving chemicals in the body and reducing inflammation without the side effects of drugs. This non-invasive approach can be used alongside other pain management methods to enhance their effects. ^{1 4 6 11 12}

Research Team

Matthew C Mauck, MD PhD

Principal Investigator

University of North Carolina, Chapel Hill

Eligibility Criteria

Adults over 18 with fibromyalgia or chronic low back pain, who rate their pain at least 7/10, can join this trial. They must be willing to use a light therapy device for two hours each morning for five days and be able to read and speak English. People with seizure disorders, severe vision impairments, color blindness, pregnancy, or prisoners cannot participate.

Inclusion Criteria

My average pain level is more than 7 out of 10.

I have been diagnosed with fibromyalgia or chronic low back pain.

I am willing to use a light therapy device for 2 hours daily in the morning.

Exclusion Criteria

Pregnancy

I am mentally capable of understanding and agreeing to the trial.

Prisoner Status

Timeline

Screening

Participants are screened for eligibility to participate in the trial

1-2 weeks

Treatment

Participants receive light stimuli via a portable battery-operated ganzfeld light stimulation device for 2 hours per day for 5 consecutive days

1 week

5 visits (in-person)

Follow-up

Participants are monitored for changes in pain intensity and activity levels after treatment

1 week

Treatment Details

Interventions

• Equal Energy White stimulation
• Green Light stimulation
• S-cone modulating white light

Trial Overview The study tests if different types of light stimuli (Green Light stimulation, Equal Energy White stimulation, S-cone modulating white light) presented through a portable device can reduce chronic pain severity and sensitivity in patients with conditions like fibromyalgia and lower back pain.

Participant Groups

Group I: S-cone modulating white light Experimental Treatment 1 Intervention

The S-cone modulating light stimulus will alternate between two light conditions at 500 lux that will activate the S-cones by about 100x differentially between the two conditions while maintaining the L- an M-cones at constant activation between the two alternating conditions using 427 nm versus 545 nm light. The stimulus will be delivered by a portable battery-operated ganzfeld light stimulation device for 2 hours per day for 5 consecutive days.

Group II: Green light stimulus Experimental Treatment 1 Intervention

Green light at 500 lux. Participants will view 545 nm green light delivered via a portable battery-operated ganzfeld light stimulation device for 2 hours per day for 5 consecutive days.

Group III: Equal energy white stimulus Experimental Treatment 1 Intervention

Equal energy white light at 500 lux. The International Commission on Illumination (CIE) coordinates of this light are (x=y=0.33), indicating that the stimulus appears uniformly white which means that the activation of each of the three classes of photoreceptors are equivalent, thus silencing any chromatic opponency. The stimulus will be delivered by a portable battery-operated ganzfeld light stimulation device for 2 hours per day for 5 consecutive days.

Who Is Running the Clinical Trial?

University of North Carolina, Chapel Hill

Lead Sponsor

Trials

1,588

Recruited

4,364,000+

Findings from Research

A 66-year-old man with color blindness experienced significant reductions in headache pain intensity after exposure to green light therapy (GLED), indicating its potential as a non-pharmacological pain management method.

The results suggest that GLED may work through non-image-forming retinal cells, while the unchanged frequency of headaches implies that other photoreceptors, like cones, might be involved in reducing headache frequency.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Case Report: Green Light Exposure Relieves Chronic Headache Pain in a Colorblind Patient. Cheng, K., Martin, LF., Calligaro, H., et al.[2022]

In a study of 200 chronic pain patients, the color of the paper used for the Numerical Rating Scale (NRS) questionnaire did not affect overall pain scores, indicating that visual stimulation alone may not influence pain perception.

However, patients on antidepressants and those with depression reported higher pain scores when using the red paper compared to the green paper, suggesting that emotional stimuli can impact pain assessment in these groups.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Visual/emotional stimuli and treatment with antidepressants alter Numerical Rating Scale score in patients with chronic pain. Kanai, A., Matsumoto, S., Hayashi, N., et al.[2017]

In a clinical trial involving 43 participants, low-level laser therapy using green and violet wavelengths significantly reduced chronic musculoskeletal pain, with visual analog pain scores dropping from 71.79 to 34.02 just three minutes after treatment (p < 0.0001).

A remarkable 81.4% of participants experienced a reduction of 30% or more in their pain scores, supporting the efficacy of this therapy and leading to the first FDA clearance for the combined use of these laser wavelengths.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Assessing the Impact of High Photon Energy Wavelengths on the Treatment of Chronic Neck and Shoulder Pain. Sammons, T., Gair, K., Silverman, RG., et al.[2023]

Phototherapy, particularly using red light (660 nm), can effectively reduce pain in conditions like neuropathies and complex regional pain syndrome-I, but visual exposure to the same wavelength may worsen migraines.

Green light exposure has been shown to alleviate pain in various conditions, including migraines and fibromyalgia, highlighting the importance of light color and exposure method in pain management.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Mechanisms and Pathways of Pain Photobiomodulation: A Narrative Review. Cheng, K., Martin, LF., Slepian, MJ., et al.[2023]

In a study involving 72 healthy university students, wearing eyeglasses that simulate watching a large television screen significantly increased both pain threshold and pain tolerance during a controlled pain-inducing procedure.

These results suggest that visual stimulation could be an effective complementary approach to enhance pain relief in various clinical settings.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The application of eyeglass displays in changing the perception of pain. Tse, MM., Ng, JK., Chung, JW., et al.[2004]

Monochromatic light sources with wavelengths under 456 nm are nearly ideal for stimulating S-cones in the human eye, with minimal impact on other cone types, making them effective for electrophysiological studies.

Blue light emitting diodes (LEDs) with a peak wavelength of 448 nm and a bandwidth of 25 nm provide approximately 95% S-cone activation, while other displays like the Trinitron monitor and multimedia projectors also show high activation rates, indicating their suitability for S-cone stimulation.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Spectral characteristics of light sources for S-cone stimulation. Schlegelmilch, F., Nolte, R., Schellhorn, K., et al.[2019]

A new type of artificial light that stimulates color-opponent signals in the retina can significantly advance circadian rhythms, with a study showing an average phase advance of 1 hour and 20 minutes in 6 participants after just 2 hours of exposure.

This light works by modulating short-wavelength sensitive cones, suggesting a novel approach to improving mood and sleep by effectively controlling circadian rhythms, compared to traditional white light which showed no phase advance.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Toward an indoor lighting solution for social jet lag. Neitz, A., Rice, A., Casiraghi, L., et al.[2023]

The new LED-S photic stimulator can effectively match the stimulus intensities of the traditional Grass Instrument stimulator (GP-S), making it a potential replacement in pediatric visual electrophysiology.

The LED-S provides uniform intensity across its surface and can generate longer stimuli, which may enhance the quality of electroretinogram (ERG) recordings compared to the GP-S, which has a significant central hot spot.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A comparison of the Grass strobe and new LED photic stimulator for paediatric electroretinogram recordings. Liasis, A., Gruszewski, J., Toro, J., et al.[2021]

Customizing a hand-held stimulator with shorter-wavelength blue (440 nm) and orange (590 nm) LEDs allowed for reproducible S-cone ERG responses, which were recorded quickly and showed typical waveforms.

Despite being able to elicit S-cone responses in most subjects, the small amplitudes and high variability of the results limit the effectiveness of this technique for routine clinical testing.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Clinical S-cone ERG recording with a commercial hand-held full-field stimulator. Marmor, MF., Cabael, L., Shukla, S., et al.[2019]

Bright light therapy is effective for treating seasonal affective disorder (SAD) and has potential applications for other conditions like circadian sleep phase disorders and jet lag, but the safety of different light sources is a concern.

The study analyzed various light therapy fixtures, revealing that many emit unknown spectral emissions that could cause ocular damage, leading to recommendations for safer lamp choices and monitoring for patients undergoing prolonged treatment.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Bright light therapy in focus: lamp emission spectra and ocular safety. Remé, CE., Rol, P., Grothmann, K., et al.[2007]

Green light therapy has been shown to effectively reduce postsurgical pain in rats, suggesting its potential as a non-pharmacological pain management option that could minimize opioid use.

The therapy enhances the pain-relieving effects of morphine and ibuprofen, particularly increasing endogenous opioid levels and reducing neuroinflammation, which could lead to improved pain control in clinical settings.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Green Light Exposure Elicits Anti-inflammation, Endogenous Opioid Release and Dampens Synaptic Potentiation to Relieve Post-surgical Pain. Martin, LF., Cheng, K., Washington, SM., et al.[2023]

Phototherapy, particularly using different colors of light, can modulate pain perception by affecting specific neural populations in the ventral lateral geniculate body (vLGN), with green light promoting antinociception and red light potentially increasing pain sensitivity.

The study utilized fiber photometry and chemogenetics to show that green light enhances glutamatergic neuron activity while red light increases GABAergic neuron activity in the vLGN, suggesting that light color can be strategically used to develop new treatments for neuropathic pain.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Glutamatergic and GABAergic neurons in the vLGN mediate the nociceptive effects of green and red light on neuropathic pain. Wu, XQ., Tan, B., Du, Y., et al.[2023]

References

1. United States pubmed.ncbi.nlm.nih.gov

Case Report: Green Light Exposure Relieves Chronic Headache Pain in a Colorblind Patient. [2022]

2. United States pubmed.ncbi.nlm.nih.gov

Visual/emotional stimuli and treatment with antidepressants alter Numerical Rating Scale score in patients with chronic pain. [2017]

3. United States pubmed.ncbi.nlm.nih.gov

Assessing the Impact of High Photon Energy Wavelengths on the Treatment of Chronic Neck and Shoulder Pain. [2023]

4. United States pubmed.ncbi.nlm.nih.gov

Mechanisms and Pathways of Pain Photobiomodulation: A Narrative Review. [2023]

5. Netherlands pubmed.ncbi.nlm.nih.gov

The application of eyeglass displays in changing the perception of pain. [2004]

6. Netherlands pubmed.ncbi.nlm.nih.gov

Spectral characteristics of light sources for S-cone stimulation. [2019]

7. United States pubmed.ncbi.nlm.nih.gov

Toward an indoor lighting solution for social jet lag. [2023]

8. Netherlands pubmed.ncbi.nlm.nih.gov

A comparison of the Grass strobe and new LED photic stimulator for paediatric electroretinogram recordings. [2021]

9. Netherlands pubmed.ncbi.nlm.nih.gov

Clinical S-cone ERG recording with a commercial hand-held full-field stimulator. [2019]

10. Netherlands pubmed.ncbi.nlm.nih.gov

Bright light therapy in focus: lamp emission spectra and ocular safety. [2007]

11. United States pubmed.ncbi.nlm.nih.gov

Green Light Exposure Elicits Anti-inflammation, Endogenous Opioid Release and Dampens Synaptic Potentiation to Relieve Post-surgical Pain. [2023]

12. United States pubmed.ncbi.nlm.nih.gov

Glutamatergic and GABAergic neurons in the vLGN mediate the nociceptive effects of green and red light on neuropathic pain. [2023]