Indian Dermatology Online Journal

: 2017  |  Volume : 8  |  Issue : 5  |  Page : 384--385

Yellow light in dermatoscopy and its utility in dermatological disorders

Balakrishnan Nirmal 
 Department of Dermatology, Christian Medical College, Vellore, Tamil Nadu, India

Correspondence Address:
Balakrishnan Nirmal
OPD No. 220, Room No. 5, Assistant Professor, Department of Dermatology, Christian Medical College, Vellore, Tamil Nadu

How to cite this article:
Nirmal B. Yellow light in dermatoscopy and its utility in dermatological disorders.Indian Dermatol Online J 2017;8:384-385

How to cite this URL:
Nirmal B. Yellow light in dermatoscopy and its utility in dermatological disorders. Indian Dermatol Online J [serial online] 2017 [cited 2022 Jan 20 ];8:384-385
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Full Text

Dermatoscopy has become increasingly significant in assisting the diagnosis of common dermatological disorders.[1] However, the main deterrent to the utility of dermatoscopy in dark skin is the presence of higher melanin content in the basal layer preventing deeper pigmentation and vessels from visualization through dermatoscopy.

Melanin absorption is highest in ultraviolet light spectrum and decreasing towards infrared spectrum. Hemoglobin has absorption peaks at UVA, blue (400 nm), green (541 nm), and yellow (577 nm) wavelengths.[2] Green light was found to offer better contrast than white light in nail fold capillaroscopy.[3] Colors with lower wavelength, such as violet, blue, and green, are absorbed by superficial layers and do not penetrate deeper. Hence, the utility of green light is limited to nail fold capillaroscopy and oral mucosal dermatoscopy.[4] Yellow, orange, and red with higher wavelengths penetrate deeper into the dermis because penetration of light into tissues increases with increase in wavelength.[5] To visualize dermal pigment and vasculature, wavelength of light should correspond to that of the absorption peaks of melanin and hemoglobin. Yellow color corresponds to an absorption peak of hemoglobin and is the closest to melanin absorption peak among the higher wavelength colors. Hence, it is ideally suited to visualize nailfold capillaries [Figure 1], conditions with alterations in dermal vasculature [Figure 2], and in conditions producing dermal pigmentation [Figure 3], where these structures stand out black against the yellow background offering better contrast.{Figure 1}{Figure 2}{Figure 3}

Addition of colors in dermatoscopy offers plenty of research on the technology and its utility in dermatologic disorders in future.

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Conflicts of interest

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