Hydrogel under-eye patches from Natura Siberica's Lab line. Fifteen to twenty minutes, on clean dry skin.
How a hydrogel patch works
The mechanism is simple and worth knowing, because it explains every rule about using them.
A hydrogel patch is mostly water held in a gel matrix. Laid on the skin it does two things simultaneously: it supplies water, and it forms a physical seal so that water cannot evaporate away. That second part — occlusion — is the whole trick. A cream is competing with the surrounding air the entire time it sits on your face; a patch is not, so in twenty minutes it pushes far more hydration into the top layers of skin than any cream can.
Hydrated skin is temporarily plumper, and plumper skin creases less. That is why the area looks visibly smoother straight afterwards. The effect is genuine and useful — and temporary, lasting hours rather than days.
Why the eye area specifically
The skin around the eye is markedly thinner than the rest of the face, has fewer oil glands, and moves constantly — every blink, every expression. It dries out faster and shows dehydration sooner than anywhere else, which is precisely why a patch produces such a visible change there and so little on a cheek.
The four rules
Chill them. Cold constricts the small vessels under the eye and does more for morning puffiness than any ingredient in the serum.
Clean, dry skin. Serum will not stay put on a damp or oily surface.
Fifteen to twenty minutes, not longer. Once a patch has given up its water it starts taking moisture back from the skin, which defeats the purpose entirely.
Do not rinse. Tap the remaining serum in and carry on with your routine.
Note
Single use. External use only — avoid direct contact with the eye; rinse with water if serum gets in. Patch test on the inner forearm first if your skin is reactive.