THE EFFECTS OF CHRONIC SUNSCREEN USE ON THE HISTOLOGIC-CHANGES OF DERMATOHELIOSIS

Background: Sunscreen application to the skin of hairless mice is effe ctive in reversing the histologic changes associated with photoaging ( solar elastosis, epidermal thickening, collagen depletion, glycosamino glycan deposition). These reparative processes have not been studied i n human beings. Objective: The aim of this study was to evaluate histo logically the effects of daily application of a UVA/UVB sunscreen vers us placebo. Methods: We examined 46 patients who were given either sun screen or vehicle and asked to apply it daily for 24 months. Punch bio psy specimens were obtained from preauricular skin at 0, 12, and 24 mo nths. Each specimen was examined for epidermal thickening and organiza tion and dermal inflammatory infiltrate by light microscopy. Computer- generated analysis of tissue sections was used to evaluate solar elast osis. Results: A significant difference in solar elastosis was found b etween the treatment groups; however, the other features remained larg ely unchanged. Conclusion: The dermal changes of photoaging may be aff ected differently than epidermal changes when UV radiation exposure is diminished. UVA and UVB may contribute diversely to these cutaneous c hanges. Computer-generated evaluation of dermatoheliosis may be more a ccurate than visual inspection.