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. Author manuscript; available in PMC: 2018 Feb 1.
Published in final edited form as: Pain. 2017 Feb;158(2):347–360. doi: 10.1097/j.pain.0000000000000767

Figure 4. Involvement of the visual system in green light emitting diode (GLED)-induced thermal analgesia.

Figure 4

(A) Bar graph of paw withdrawal latency (seconds) of rats (n=6 per group) prior to and after treatment with GLED as indicated. During the GLED exposure paradigm, the rats were fitted with clear or dark plastic lenses on their eyes. Blocking green LED absorbance to the eyes with dark contacts prevented the development of GLED-induced thermal analgesia. (B) Rats ‘wearing’ green plastic eye contacts and exposed to ambient room light for eight hours daily, developed thermal analgesia on days 3 and 4. *p<0.05 when comparing to baseline (BL) (one-way ANOVA followed by Student-Newman-Keuls test). (C) Absorbance spectra, in arbitrary units (a.u.), of clear, dark, or green contacts. Dark contacts absorbed light in all wavelengths while green contacts showed a peak absorbance in the 580–700 nm range.