After 4 weeks of twice-daily mandelic acid, users saw their lower eyelid skin elasticity jump 25.4% and firmness increase 23.8%—measurable improvements that matched what they saw in the mirror. Mandelic acid is an alpha-hydroxy acid that works on acne and dark spots, and this study shows it actually does firm and bounce back aged skin, at least around the delicate eye area.

24 people (mostly women, ages 42-68) applied mandelic acid twice daily for 4 weeks while researchers used a device called a Cutometer to objectively measure changes in skin elasticity and firmness each week, rather than relying on photos alone.

Funding not disclosed in abstract