Chromatic Retinal Stimulation to Reduce Chronic Pain and Pain Sensitivity

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.

Study Overview

• Status: Suspended
• Conditions: Chronic Pain; Chronic Low-back Pain; Fibromyalgia
• Intervention / Treatment: Device: Equal Energy White stimulation; Device: Green Light stimulation; Device: S-cone modulating white light

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • North Carolina
    • Chapel Hill, North Carolina, United States, 27517
      • University of North Carolina

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Adults greater than or equal to 18 and less than or equal to 65.
• Individuals who have been diagnosed with fibromyalgia or chronic low back pain by their physician.
• Individuals who experience an average pain severity greater than 4/10 in intensity at baseline.
• Willingness to wear a battery-operated portable ganzfeld light stimulator device for 2 hours per day at the same time each day (ideally complete the light therapy session between 5 am-10 am each morning) for 5 days.
• Alert and oriented, and able to provide informed consent
• Ability to read and speak English to complete validated questionnaires.

Exclusion Criteria:

• Vision disorders or conditions resulting in severe vision impairment or blindness
• Individuals with self-report of color blindness
• Prisoner Status
• Pregnancy
• No other history or condition that would, in the investigator's judgment, indicate that the patient would very likely be non-compliant with the study or unsuitable for the study (e.g., might interfere with the study, confound interpretation, or endanger the patient).
• History of seizure disorder

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Equal energy white stimulus; 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.	Device: Equal Energy White stimulation; A portable battery-operated ganzfeld light display will be used to deliver white light for 2 hours per day for 5 consecutive days.
Experimental: Green light stimulus; 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.	Device: Green Light stimulation; A portable battery-operated ganzfeld light display will be used to deliver green light for 2 hours per day for 5 consecutive days.
Experimental: S-cone modulating white light; 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.	Device: S-cone modulating white light; A portable battery-operated ganzfeld light display will be used to deliver S-cone modulating light for 2 hours per day for 5 consecutive days.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Feasibility: Percent follow-up	Percent follow-up for 1 week baseline visit. Follow-up greater than 70% will be considered feasible.	1 week
Feasibility: Percent of flash surveys completed	Percent of flash surveys completed during light stimulation period. 0% is the lowest and 100% is the highest. Higher percentages indicate greater percent of flash surveys completed.	1 week
Feasibility: Self-reported light stimulation sessions completed	Self-reported light stimulation sessions completed by flash survey administered after each light stimulation session over the 5 day stimulation period. Number of sessions will be reported the minimum is 0 and the maximum is 5.	1 week

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in pain intensity after stimulation	Pain intensity measured by a 0-10 numeric rating scale for overall pain. 0 represents no pain, and 10 represents the worst pain imaginable.	Baseline, 1 week
Change in pressure pain threshold	Pressure Pain Threshold is the threshold in which pain is experienced in response to increasing force applied to the trapezius measured by a pressure algometer in kilograms of force per square centimeter (kgf/cm^2). The higher the value, the higher the threshold. The maximum is 10 kgf/cm^2 and minimum is 0.	Baseline, 1 week
Change in Conditioned Pain modulation	Conditioned Pain modulation magnitude will be calculated as the difference in mean pressure pain threshold (kgf/cm^2) measured prior to and during the conditioning stimulus (cold water bath), with increases in pressure pain threshold during conditioning interpreted as evidence of efficient endogenous pain inhibition.	Baseline, 1 week
Change in Temporal Summation	Temporal Summation. The investigators will evaluate temporal summation using a 40g Neuropen applied to the skin of the volar forearm and lumbar region, following a train of 10 identical stimuli (1 Hz). Participants will report retrospectively, the pain intensity of the 1st and 10th pinprick using a 0-10 numerical rating scale (NRS). 0 is the minimum and 10 is the maximum pain intensity that will be reported.	Baseline, 1 week
Change in activity measured with an accelerometer	Activity will be measured by an accelerometer. Average daily step count for the duration of the stimulus. Average non-sedentary time in minutes will able be determined over the stimulation period and compared to the data collected over the 1 week run-in period.	1 week prior to baseline and 1 week during light stimulation

Collaborators and Investigators

• Sponsor: University of North Carolina, Chapel Hill
• Investigators: Principal Investigator: Matthew C Mauck, MD, PhD, University of North Carolina, Chapel Hill

Study record dates

Study Major Dates

• Study Start (Actual): August 25, 2023
• Primary Completion (Estimated): July 17, 2026
• Study Completion (Estimated): July 29, 2026

Study Registration Dates

• First Submitted: June 28, 2023
• First Submitted That Met QC Criteria: July 13, 2023
• First Posted (Actual): July 21, 2023

Study Record Updates

• Last Update Posted (Actual): February 17, 2026
• Last Update Submitted That Met QC Criteria: February 13, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Musculoskeletal Diseases; Nervous System Diseases; Muscular Diseases; Neuromuscular Diseases; Rheumatic Diseases; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Fibromyalgia; Chronic Pain
• Other Study ID Numbers: 23-1301

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Deidentified individual data that supports the results will be shared beginning 9 to 18 months following publication provided the investigator who proposes to use the data has approval from an Institutional Review Board (IRB), Independent Ethics Committee (IEC), or Research Ethics Board (REB), as applicable, and executes a data use/sharing agreement with the University of North Carolina.
• IPD Sharing Time Frame: Data will be available 1 year after completion of the study and will be available for an additional 2 years.
• IPD Sharing Access Criteria: Data use agreement with University before deidentified information requested will be shared.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No