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 Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
NONE
Enrollment
60
A portable battery-operated ganzfeld light display will be used to deliver green light for 2 hours per day for 5 consecutive days.
A portable battery-operated ganzfeld light display will be used to deliver white light for 2 hours per day for 5 consecutive days.
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.
University Of North Carolina
Chapel Hill, North Carolina, United States
Feasibility: Percent follow-up
Percent follow-up for 1 week baseline visit. Follow-up greater than 70% will be considered feasible.
Time frame: 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.
Time frame: 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.
Time frame: 1 week
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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 1 week prior to baseline and 1 week during light stimulation
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