# In Vivo Assessment of Water Content, Trans-Epidermial Water Loss and Thickness in Human Facial Skin
## 4 Results  
### Anatomical Variations of the Water Content  
As can be seen from Table 1 and Figure 5(a) the water content in the different facial areas was, on the whole, rather uniform (range 21.8-26.5 \(\epsilon\), a.u.). The cheeks emerged as the area with the highest hydration, followed by the neck and chin. By contrast, the lips were the area with the least water content. Pairwise comparison revealed statistically significant differences between five pairs out of 15 comparisons (Table 2(a)). Cluster analysis showed three prominent clusters: (1) chin, forehead, neck and nose; (2) cheeks, chin and neck; and (3) forehead, lips and nose (Figure 6).  
Figure 4: Episcan I-200 ultrasonic dermal scanner (**left**) and sample scans (**right**).  
Figure 5: Box-plots/strip-plots showing the water content and trans-epidermal water loss at the six facial sites.  
\begin{table}
\begin{tabular}{l c c c} \hline \hline  & \multicolumn{3}{c}{**(a)**} \\ \hline
**Area** & \multicolumn{2}{c}{**Water Content**} & \multicolumn{2}{c}{**TEWL**} \\  & \multicolumn{2}{c}{**[\(e\), a.u.]**} & \multicolumn{2}{c}{**[g/m2h]**} \\ \hline Cheek & 26.5 \(\pm\) 7.4 (24.2, 11.3) & 20.4 \(\pm\) 11.9 (17.6, 9.9) \\ Chin & 25.3 \(\pm\) 7.0 (23.2, 8.9) & 32.3 \(\pm\) 15.5 (30.1, 14.5) \\ Forehead & 24.0 \(\pm\) 6.4 (22.6, 11.2) & 27.2 \(\pm\) 17.7 (21.9, 10.2) \\ Lips & 21.8 \(\pm\) 5.8 (20.9, 8.2) & 66.9 \(\pm\) 23.6 (71.0, 27.5) \\ Neck & 26.2 \(\pm\) 8.2 (25.0, 7.2) & 15.7 \(\pm\) 10.6 (12.9, 9.8) \\ Nose & 23.1 \(\pm\) 4.7 (22.1, 6.4) & 37.5 \(\pm\) 15.2 (35.3, 12.8) \\ \hline \hline \end{tabular}
\begin{tabular}{l c c c} \hline \hline  & \multicolumn{3}{c}{**(b)**} \\ \hline  & \multicolumn{3}{c}{**The thickness [\(\mu\)m]**} \\ \cline{2-3}  & \multicolumn{2}{c}{**SC**} & \multicolumn{2}{c}{**Epidermis**} & \multicolumn{2}{c}{**Dermis**} \\ \hline Cheek & 27.6 \(\pm\) 13.0 (20.0, 10.0) & 51.8 \(\pm\) 21.2 (50.0, 40.0) & 1610.8 \(\pm\) 742.1 (1525.0, 452.5) \\ Chin & 26.3 \(\pm\) 10.7 (20.0, 10.0) & 65.4 \(\pm\) 25.9 (70.0, 30.0) & 1837.1 \(\pm\) 479.7 (1840.0, 610.0) \\ Forehead & 24.6 \(\pm\) 10.1 (20.0, 10.0) & 53.7 \(\pm\) 22.6 (50.0, 30.0) & 1569.0 \(\pm\) 292.6 (1550.0, 270.0) \\ Lips & 32.4 \(\pm\) 16.3 (30.0, 20.0) & 73.9 \(\pm\) 33.6 (80.0, 40.0) & 1320.1 \(\pm\) 530.3 (1220.0, 705.0) \\ Neck & 32.8 \(\pm\) 12.8 (30.0, 20.0) & 77.4 \(\pm\) 36.5 (80.0, 50.0) & 1267.4 \(\pm\) 320.7 (1220.0, 485.0) \\ Nose & 27.0 \(\pm\) 12.9 (20.0, 10.0) & 64.3 \(\pm\) 32.2 (70.0, 40.0) & 1820.6 \(\pm\) 563.5 (1740.0, 885.0) \\ \hline \hline \end{tabular}
\end{table}
Table 2: Water content and TEWL: results of the pairwise comparisons (\(p\)-value) between the six facial areas. Significant differences (\(\alpha^{*}=3.3\times 10^{-3}\)) are highlighted.  
Figure 6: Results of the cluster analysis on the distribution of water content. From left to right, in descending order of water content: (1) cheeks, chin and neck; (2) chin, forehead, neck and nose; and (3) forehead, lips and nose.  
\begin{table}
\begin{tabular}{l c c c c c} \hline \hline  & \multicolumn{3}{c}{**(a) Water Content**} \\ \hline  & \multicolumn{2}{c}{**Chin**} & \multicolumn{2}{c}{**Fhead**} & \multicolumn{2}{c}{**Lips**} & \multicolumn{2}{c}{**Neck**} & \multicolumn{2}{c}{**Nose**} \\ \hline Cheeks & 0.2 & 4\(\times\) 10\({}^{-4}\) & 4\(\times\) 10\({}^{-2}\) & 0.9 & 6\(\times\) 10\({}^{-4}\) \\ Chin & – & 7\(\times\) 10\({}^{-2}\) & 2\(\times\) 10\({}^{-4}\) & 0.4 & 3\(\times\) 10\({}^{-2}\) \\ Fhead & – & – & 8\(\times\) 10\({}^{-3}\) & 4\(\times\) 10\({}^{