While some maintain that long eyelashes enhance one's beauty, others have found in a scientific study that they may not be practical at all.
According to Live Science, authors of a study published in the Journal of the Royal Society Interface found that eyelashes follow the rule of thirds. The optimal length for a person's lashes is one-third the width of the eye.
Scientists have wondered why people have lashes and the researchers have offered another possibility: to keep the eye from getting dry.
"They've been hypothesized to act as sun shades, dust catchers and blink-reflex triggers," study co-author David Hu, a mechanical engineer at the Georgia Institute of Technology, told Live Science. "But there's been no really systematic study of what their true benefits are.
"We found that there's a pretty good trend for how lashes change with eye width," he said. "That's quite striking because in the mammal-hair literature, you don't see many trends. Hair is usually a function of habitat, activity, things like that."
For their study, the researchers outfitted petri dishes with false lashes of different lengths and put them in front of a wind tunnel. With water in each dish, the optimal-sized lashes prevented evaporation best.
"Eyelashes form a barrier to control airflow and the rate of evaporation on the surface of the cornea," study lead author Guillermo Amador, a Georgia Tech Ph.D. candidate in the George W. Woodruff School of Mechanical Engineering, said in a press release. "When eyelashes are shorter than the one-third ratio, they have only a slight effect on the flow. Their effect is more pronounced as they lengthen up until one-third. After that, they start funneling air and dust particles into the eye."
