Clinical evaluation method for blue light (456 nm) protection of skin

Abstract

BackgroundBlue light from electronic devices enriched with a peak at 456 nm affects circadian rhythm and antioxidant balance of skin, necessitating the study of photoprotection against the 456‐nm blue light.AimsThis study aims to report that blue light (456 nm) can cause skin pigmentation and proposes a new clinical evaluation method for blue light (456 nm) protection based on the skin pigmentation level.Patients/MethodsWe developed a clinical device (ABC deviceTM) that emits blue light (peak = 456 nm). Based on the minimal persistent pigment darkening dose (MPPD) determined from visual evaluation and melanin index measurements, we proposed the “protection grade of blue light (PB)” guideline to assess the protective ability of skin against blue light.ResultsHuman skin irradiated with blue light (456 nm) showed a light dose‐dependent degree of pigmentation. The MPPD on unprotected and protected skin was 135 J/cm2 or 180 J/cm2 and 135‐225 J/cm2, respectively. The ABC device™ and the proposed clinical method were used to test the four blue light blocking assessments of TiO2. Consequently, the inorganic filter with TiO2 effectively blocked the blue light (456 nm). The AP product demonstrated the ability to block blue light by 1.15 times (PB = 1.15), which significantly lowered the melanin index of the skin after irradiation as compared to that of the unprotected skin (P < .001).ConclusionWe propose an objective clinical evaluation method for blue light protection. This study elucidates the properties of blue light blockers for customers suffering from blue light pollution.

Visible Light and the Skin

“…Jo et al . (31) utilized a blue light device (peak emission at 456 nm, full width at half maximum 20 nm) to irradiate the back of healthy subjects (SPT III–IV) with doses ranging from 45 to 270 J cm −2 . Similar to Ruvolo et al ., VL‐PF was suggested to be calculated as the ratio of visually determined minimal persistent pigment darkening dose, 2–4 h after irradiation, between treated and untreated skin.…”

Blue light protection, part II—Ingredients and performance testing methods

“…46 As it was discussed in Part I of this article, blue light exposure leads to oxidative stress, which can be tested in multiple ways, many blocking performance at those harmful wavelengths. 49 As it was mentioned in Part I of this article, superoxide is the main free radical produced by blue light exposure. The expression of superoxide dismutase, an enzyme that assists with the breakdown of superoxide radicals, can be measured in the skin and used as a measure of cellular antioxidant potential.…”

Combined Analysis of the Effects of Exposure to Blue Light in Ducks Reveals a Reduction in Cholesterol Accumulation Through Changes in Methionine Metabolism and the Intestinal Microbiota

“…Due to its fruitful broad-spectrum antibacterial effect ( 6 – 8 ), LED blue-light irradiation has been used for the treatment of skin diseases and wound sterilization ( 9 – 11 ). Various studies have revealed that blue light also plays a role in regulating physiological functions in vivo , e.g., it improves cognitive performance ( 12 ), promotes cell proliferation and differentiation ( 13 , 14 ), and even inhibits tumor cell growth and metastasis ( 15 , 16 ).…”