8.3.1.1　Skin thickness

The skin thickness of individuals of different ages，genders，locations，and ethnicities may vary.For example，the thickness of the skin at the eyelid is about 0.5 mm，while that at the palm and plantar part can be up to 3-4 mm.In general，the stratum corneum is thicker where the skin is thicker，making it more difficult for drug penetration.(https://www.daowen.com)