The objective of the study was to quantify the UV transmission of split skin exposed to UVB radiation and of non-exposed skin and to compare the two values.
The study population consisted of 10 patients. Two specimens of split skin having the dimensions 1 cm x 1 cm and with a thickness of 0.3 mm were taken from each patient. In each case, one specimen was taken from an area of normal healthy skin and one from an area that had been exposed to UVB radiation (the initial dose of 1/3 MED was raised by 1/3 MED every 4 days) for 12 days.
The split-skin specimens were streched until they exhibited the tension previously measured in vivo.
The UV transmission was measured with a Cary 3 Bio (VARIAN) spectrophotometer.
In the split-skin specimens exposed to UVB radiation, the mean transmission values were 50 % lower than in the non-exposed skin.
The ultraviolet protection factor (UPF) of the split-skin specimens was subsequently calculated from the transmission data. The UPF of split skin exposed to UVB radiation was found to be three times as high as the UPF of non-exposed skin.
The study had thus succeeded in objectifying and exactly quantifying the natural protection factor triggered by UVB radiation.