Morphological study of the relationship between solar elastosis and the development of wrinkles on the forehead and lateral canthus.

OBJECTIVE To identify whether there is a relationship between solar elastosis and the development of wrinkles in human skin. DESIGN Wrinkle depth was measured on the forehead and lateral canthus of human cadavers using image analysis. The thickness of the dermis was measured in skin sections obtained around wrinkles and stained with Elastica-van Gieson. SETTING Gross Anatomy Section, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan. SUBJECTS Fifty-eight male and female cadavers (age range at death, 29-93 years). MAIN OUTCOME MEASURES The ratio of solar elastosis dermal thickness to full dermal thickness (elastosis ratio) was calculated and compared between the deepest point of a wrinkle (wrinkle point) and a point within 1 mm where no wrinkle existed (nonwrinkle point). The relationship between elastosis ratios and wrinkle depths was investigated. RESULTS Advanced solar elastosis was present at nonwrinkle points but was present a little bit at wrinkle points. On the forehead, a positive correlation between elastosis ratios and wrinkle depths was observed at nonwrinkle points but not at wrinkle points. On the lateral canthus, a positive correlation between elastosis ratios and wrinkle depths was observed at nonwrinkle points, as well as at wrinkle points until the wrinkle became deeper than one-half of the original dermal thickness (0.6 mm). Solar elastosis on the lateral canthus ceased developing at this point, but the wrinkle developed further. CONCLUSIONS Solar elastosis tends to commence with the development of a wrinkle until the wrinkle becomes deeper than 0.6 mm. This tendency is less evident at wrinkle points than at nonwrinkle points.