174 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 140 CHEEK ' BO • 60 Ld 40 X 20 o 1 (1-2) 2 nRYNESS SCORE Figure 2. Relationship between skin extensibility measured on cheek (arbitrary units) and dryness scores. ELECTRICAL CONDUCTANCE On both the cheek and the forehead, conductance was inversely related to the degree of dryness (r = -0.66 for cheek and -0.41 for forehead). While the correlations were relatively weak, especially on the forehead, the differences among the grades were sig- nificant for both areas (p 0.001 and p 0.002) (Figure 3). CORNEOCYTES The size of exfoliated corneocytes decreased with increasing dryness scores (Figure 4). The differences were significant (r = -0.32, p 0.05 on the cheek and r = -0.22, p 0.05 on the forehead). SER AND TEWL The SER was not found to correlate with the dry skin scores (r = 0.03, p = 0.85). A statistically significant trend (r = 0.28, p = 0.04) was observed with TEWL and the dry skin scores.

DRY FACIAL SKIN 175 i,i u z u z o u IS 10 CHEEK FOREHEAD 1 (1-2) 2 1 (1-2) 2 •iRYNESS SCORE Figure 3. Evaluation of skin conductance (arbitrary units) with the severity of skin dryness on cheek and forehead. DISCUSSION •/hile physical measurements are straight forward and rigorous, the skin is so complex and so easily perturbed by even slight external changes, that the data must be viewed cautiously. Easy interpretations which fit expectations should be avoided. Conductance illustrates the difficulties in interpretation. A wetter horny layer will conduct electricity more effectively. Therefore, decreased conductance should be associated with dryness, and it often is. However, one has to take into account the degree of intimacy between the sensing probe and the skin surface with all its irregularities. Scales of course make the surface even rougher and lessen contact. Also, since the flow of an electric current through skin is exceedingly complex and dependent in more than water content, it might well reflect other parameters such as the thickness of the stratum corneum, casual sebum level, nonapparent sweating, etc. •/e did find, nonetheless, that conductance, as expected, decreased in dry skin, especially on the cheek. This corresponds to clinical experience, too. Since women rarely complain of dry skin on the forehead, these two sites are quite different anatomically. There are no ambiguities of this type in the extensibility measurements. It is quite evident that the horny layer becomes more brittle and less stretchable with increasing dryness. Cooper et al. recently noted this effect (9). Still, a simple lack of water may be too shallow an explanation. For example, the horny layer could be thicker and qualitatively altered as well. Measurement of TE•/L did not closely correlate with dryness. Generally speaking, an increase in TE•/L suggests a disturbance in the structure of the horny layer, e.g., when barrier function is strongly compromised as in the case of psoriasis or after detergent damage (10, 11). In these cases TE•/L is always elevated. The tendency