How eyelashes can protect the eye through inhibiting ocular water evaporation: a chemical engineering perspective

Abstract

<jats:p>Bionics is a fascinating subject that has inspired many inventions through learning from biological structures and functions. In this work, a coupled multi-physics model has been developed to characterize ocular water evaporation with realistic eyelash structures taken into account. From a chemical engineering perspective, the protective function of human eyelashes in terms of evaporation inhibition has been rationally revealed. Systematic investigations were carried out to elucidate the effects of different eyelash lengths, orientations and inlet air directions on water evaporation on the ocular surface. The results clearly demonstrate that regardless of inlet air directions and eyelash orientations, increasing eyelash length from zero to an optimal length can effectively reduce water evaporation. However, further increase in the eyelash length can lead to enhanced evaporation. For the normal and parallel inlet air directions, the optimal eyelash length is around 15–30% of the eye width and can offer approximately 10–30% evaporation reduction when compared with the cases without eyelashes. These values are independent of the eyelash orientation. This investigation provides valuable data for in-depth understanding of the protective function of the eyelashes, which can be used in the future to improve and optimize bionic designs inspired by human eyelashes.</jats:p>

Open clinical trial evaluating the efficacy of a novel eyelash growth enhancer with peptides and glycosaminoglycans

“…Consequently, our study documented a notably substantial increase in both curvature and arc, suggesting that these enhancements serve to improve not just the aesthetic appearance but also the functional efficacy of the eyelashes. 5 This correlation underscores the dual benefit of our product, accentuating the lashes' protective role against environmental elements while simultaneously enhancing their visual appeal.…”

“…An in vitro study on the aerodynamics of eyelash structure has shown their essential role in eye protection. Utilizing a mammalian eye model in a wind tunnel simulation to assess airflow dynamics, researchers identified that the ideal eyelash length is one‐third of the eye's width—a measurement significantly reducing tear evaporation and deposition of foreign particles 5,15 . This optimal length, determined by biomechanical efficiency, suggests that while longer lashes might be aesthetically favored, they could impede their protective function if they exceed this proportional threshold.…”

“…Fundamental for ocular health, eyelashes serve as a protective barrier for the eye, preventing foreign particles, including dust and debris, from damaging the ocular surface. Furthermore, eyelashes play a crucial role in reducing the risk of eye desiccation 4,5 …”

“…Furthermore, eyelashes play a crucial role in reducing the risk of eye desiccation. 4,5 In the field of cosmetics, eyelashes play a pivotal role in enhancing facial aesthetics. Lashes that possess desirable length, fullness, and curvature are particularly sought-after features.…”

Vital Role of the Eyelashes in Keeping the Eye healthy

“…Another important function deserving further investigation is the inhibition of ocular water evaporation since a moist ocular surface is critical for the health of eyes [14]. The answer might seem simple: Those thick hairs on the end of our eyelids simply exist to block intruding particles from landing on our eyeballs.…”