Evaluation of Anti-wrinkle Efficacy

The anti-wrinkle efficacy of cosmetics can be evaluated by recording the changes in facial wrinkles during the use of the test sample and comparing it to a control sample. In the anti-wrinkle test, the test results place high demands on the design of the test protocol, the accuracy of the test instrument, and the ability of the testers to perform the test.

Anti-wrinkle Efficacy Testing Methods

• In vitro assays

In vitro cell cultures and models can be used to evaluate the anti-wrinkle effects of cosmetics. Tests can be performed based on fibroblasts for in vitro proliferative capacity, collagen content, antioxidant-related indicators and aging-related biological indicators. As for anti-wrinkle efficacy, 3D skin models can simulate the structure of normal human skin and are closer to the real state of human body compared to single-layer cell culture due to its compound mechanism.

The active substances are formulated into creams and applied to the skin model, and the effect of cosmetics on cell proliferation and differentiation and antioxidant capacity can be examined by testing the free radical scavenging ability, antioxidant capacity, collagen content and other indicators and histomorphological changes of the model.

• Human experiment

The most common methods used in human subjects are subjective evaluation and objective instrumental evaluation.

• Subjective evaluation method

The subjective evaluation method first requires grading standards, and the most commonly used wrinkle grading method is the Glogau typing method, which grades wrinkle alertness according to dynamic or static wrinkles, the degree of photoaging and age. Internal wrinkle grading criteria can also be set up to allow subjects to evaluate the before and after state from several items such as skin laxity, skin elasticity, wrinkles, skin whiteness and discoloration, and then evaluate the anti-wrinkle effect of products or actives through the assessment and scoring by dermatologists.

• Objective instrument evaluation method

The objective instrument evaluation method focuses on the following points measured by instruments:

Moisturizing capacity test: the moisture content of the stratum corneum and the skin barrier function to evaluate the moisturizing function;

Skin elasticity determination: the most commonly used suction method designed based on the principle of suction and stretch;

Skin chromaticity test: determined by using the Lab chromaticity system colorimeter.

Cosmetic Anti-wrinkle Efficacy Assessment Test Items

Throughout the anti-wrinkle efficacy assessment test cycle, subjects are required to visit the laboratory at specified time points to undergo three major tests: skin wrinkle parameter determination, facial imaging acquisition and clinical assessment by a dermatologist.

• Skin wrinkle parameter measurement

A 3D image of the skin surface structure is obtained using streak light projection technology to measure wrinkle-related data, such as depth, volume, area, and length of wrinkles.

• Facial imaging acquisition

In the anti-wrinkle efficacy assessment test, images of the subject's front and left and right faces can be acquired separately, and the computer software automatically draws the area around the eyes for wrinkle analysis to provide data support for the entire anti-wrinkle efficacy assessment.

• Clinical evaluation by dermatologists

In addition to the instrumental test, the dermatologist also conducts visual and photographic evaluation of the wrinkles around the subject's eyes. The visual evaluation is based on the evaluation criteria for the outer corner of the eye, and the photographic evaluation is based on the same criteria for the outer corner of the eye.