It is mainly seen on the sole of the foot (palms of the hand and fingers can also be affected) and appears as a yellowish thickening. In most cases, it is painless. Once exposed to excessive and constant pressure, it can also get worse and crack (see also: Instant help for cracked heels). Little to moderate callus formation is nothing but a cosmetic or aesthetic problem; especially when wearing open shoes. Yet thickening of the affected areas can lead to painful and incommoding callus formation.
„It‘s a thin line between an aesthetic issue and an incommodity“
Medical background: The stratum corneum (cornea = horny skin/Lat.) is the uppermost layer of the epidermis. Between the cornified cells (corneocytes) lie the epidermal lipids. The horny layer - especially the bottom third - forms the permeability barrier, which is the skin‘s true barrier against exogenous factors and endogenous water loss.