Reader's Digest states that a person puts cucumbers on the eyes in an attempt to reduce under-eye puffiness. The benefits of this treatment have not been proven.
The Huffington Post indicates the skin under the eye swells because of too much lymphatic fluid. Refrigerated cucumbers cool the skin through evaporation, which is thought to decrease skin's puffy appearance. In addition, if the skin is irritated, the antioxidants and flavinoids in cucumbers sometimes help relieve the soreness. People who want to reduce under-eye puffiness are advised to avoid adding salt to their food, limit food with excessive salt content and drink enough water.