Correlation of skin phototype with facial wrinkle formation.

Facial wrinkle formation is a representative sign of photoaging. Skin can be divided into different skin phototypes (SPTs) depending on its sensitivity to solar radiation. We have determined the relationship between SPTs and deep and fine wrinkle scores on the faces of 230 Japanese subjects. This group was chosen because it is relatively easy to quantify acute and chronic sun damage in Japanese individuals. SPT in the Japanese subjects was classified into one of four groups, SPT-I to -IV according to Fitzpatrick's classification method. The subjects were further classified into indoor or outdoor workers. After photographing the outer canthus, deep and fine wrinkles were discriminated visually and scored from 1-11 and from 1-9, respectively. UV light was used as a photographic light source for clear depiction of the fine wrinkles. Higher scores were recorded for deep wrinkles in individuals with SPT-I, who are more sensitive to sunlight than those with SPT-III or IV, who are more tolerant to sunlight. However, the same tendency did not seem to be apparent for fine wrinkle scores. A high incidence of SPT-IV was seen in outdoor workers. Early detection of SPT-I in individuals who are sensitive to sunlight, may help to predict and prevent photoaging of deep wrinkles. Sensitivity to sunlight may play a part in determining an individual's choice of working environment.