On the repeatability of wrinkling topography patterns in the fingers of water immersed human skin

Finger wrinkling during and after water immersion, often called pruning, is an evolutionary mechanism that increases grip strength in water. Previous studies have determined that water-induced finger wrinkles result from vasoconstriction, or the tightening of blood vessels below the skin's surface. However, no previous studies have characterized the morphology of topographical finger wrinkles. We anticipate that vasoconstriction also governs the morphology of finger wrinkles formed. Since these constricting blood vessels are stationary, we expect the pattern created by topographical wrinkles formed to remain constant over time. To evaluate pattern repeatability, images of human fingertips at two separate time points are overlaid and compared visually to establish corresponding wrinkle pairs. Wrinkle pairs are vectorized with orientation correlations evaluated quantitatively using normalized dot products, then compared against randomly oriented control vectors. The results demonstrate a significant relationship between wrinkle orientation across both time points and thus reveal the consistency of wrinkle morphology over time.