Multimodal Assessment of Structural and Spectral Changes in Aging Skin Induced by Topical Application of Stabilized Retinaldehyde at 0.1% and 0.05%: A 24-Week Split-Face Study

The goal of this clinical trial is to learn if retinaldehyde cream improves the appearance of aging skin in women aged 30 to 60 years. Retinaldehyde is a form of vitamin A that the skin can convert into retinoic acid, which is known to help with skin aging. The study tested two strengths of retinaldehyde cream: a stronger version with 0.1% retinaldehyde and a weaker version with 0.05% retinaldehyde. The main questions the study aimed to answer were: whether retinaldehyde cream improves skin hydration and reduces oiliness, whether it improves skin firmness and elasticity, whether it reduces wrinkles and improves skin texture, whether it reduces uneven skin tone and pigmentation, and whether the stronger 0.1% cream works better than the weaker 0.05% cream. Researchers compared the two cream strengths by applying them to opposite sides of the same face. The stronger 0.1% cream was applied to the left side and the weaker 0.05% cream was applied to the right side. This approach allowed researchers to compare the two strengths directly in the same person under the same conditions. 56 women with visible signs of aging skin took part in the study at the Medical University of Silesia in Poland. One participant left the study early due to skin irritation. The remaining 55 women completed all 24 weeks of the study. Participants apply the creams in the evening, starting with twice a week for the first 2 weeks, then increasing to 3 times a week in week 3 and 4 times a week in week 4, based on skin tolerance, for 24 weeks total. They also used a provided skincare routine every day, which included a lipid face cream, a cleansing lotion, and a sunscreen with SPF 50 to protect their skin during the study. Participants were assessed 3 times: before starting the creams, after 12 weeks of use, and after 24 weeks of use. At each visit, researchers measured skin hydration, oiliness, elasticity, firmness, wrinkle depth, skin density, skin color, and other skin properties using a range of specialized skin measurement tools. Neither the participants nor the researchers assessing outcomes knew which cream strength was applied to which side of the face.