I must confess I do not read the Journal of the Royal Society Interface regularly, but luckily, the ECONOMIST devoted two thirds of a page to describing how eyelashes work. Eyelashes were last discussed in this blog on Oct 29, 2013, showing a dogged persistence and perseveration about this skin appendage, which is often relegated solely to the cosmetic domain.
The basic finding in the study is that the average length of the eye lashes is about one third of the eye’s width in the 22 animal species studied. Seeing a constant mathematical relationship set the boffins to deriving mathematical and physical models to explain the basis for it. Most believe that dust, and other physical matter gets stuck on the cilia, but there is a new and deeper interpretation from these new studies. Eyelashes control the flow of air to and around the cornea so that the water in the corneal film does not evaporate excessively. The ever-imaginative authors built wind tunnels to test these functions and to derive differential equations to describe their results. Question for those of us who don’t do advanced math: if eyelashes are longer and wider owing to drugs, or if eyelash extenders are applied, will this alter the physiological water balance between the tear film and the cornea? (When you charge eyelash extensions to your research grant funds, please have an excellent justification.