A study conducted in 2015 assessed the use of 3% caffeine combined with 1% vitamin K in an emu oil base on the eye contour. More specifically, this trial in vivo was carried out to investigate the anti-wrinkle and anti-dark circle efficacy of this active ingredient combination on the right eye contour of 11 women over a four-week period. The study was controlled and compared with a placebo composed of water and applied under the left eye.
Caffeine is known for both tightening capillaries and increasing overall skin blood flow, effects that could enhance the appearance of the eye contour. It also helps to neutralise harmful free radicals that can cause collagen degradation and lead to the formation of wrinkles. Vitamin K, on the other hand, helps to strengthen capillary walls and reduce the visibility of blood vessels through the thin skin under the eyes.
After four weeks, the skin around the right eye of all subjects experienced a reduction in wrinkle depth and dark circles, and from a subjective standpoint, the appearance and elasticity of the skin were improved. Thus, the clinical study demonstrated that the application of the active formulation had a cumulative effect on hydration, pigmentation, and elasticity, thereby enhancing the appearance of the eye contour.
Note : emu oil is capable of penetrating through the dermal layer to prevent cells from dehydrating due to its high levels of unsaturated fatty acids (linolenic acid, oleic acid), enhancing the structure and function of cell membranes, as well as the skin's barrier function.
What are the limitations of this study?
However, these results need to be considered with caution. Indeed, the "depigmenting" power of this formula is far from established. In fact, the data presented on pigmentation show a high variability, illustrated by long confidence intervals, indicating that the values are more dispersed and there is a large uncertainty in the measurements presented. Moreover, the study was only conducted on 11 candidates, which represents a small sample size. Thus, although the results obtained seem encouraging regarding the corrective action of caffeine on wrinkles and brown circles, further research would be necessary to confirm its effects.