Optical characteristics of the skin with dark circles using pump-probe imaging

Pump-probe imaging was first used for quantitative analysis of melanin in dark circles' skin to improve the ability to diagnose and treat dark circles on human skin. This study aimed to compare the distribution characteristics in melanin of lower eyelid skin tissues and to determine whether pump-probe imaging has potential for the classification of dark circles in vivo. Specimens obtained from 15 patients undergoing blepharoplasty were examined using pump-probe imaging. Furthermore, adjacent slices were respectively treated with hematoxylin-eosin (HE) and ferrous sulfate (FeSO₄) staining for cross-references. Subsequently, the melanin content index (MCI) and mean fluorescence intensity (MFI) were quantitatively analyzed by the pump-probe imaging. The distribution of melanin granules in the pump-probe image and FeSO₄ staining was consistent. Meanwhile, the tissues of the skin with dark circles and normal skin demonstrated significant differences in MCI and MFI. These differences can be used to distinguish the skin with dark circles from the normal skin. Pump-probe imaging could be used for the analysis of the microstructure and spectral characteristics of melanin granules in skin with dark circles. Significant differences were noted between the pigmented type of dark circles and the other two groups (normal skin and the vascular type of dark circles), while no significant differences were found between normal skin and the vascular type of dark circles.