WASHINGTON: Wearing long, fake eyelashes may lead more air and dust to hit the eyes causing them to dry out, a new study suggests. 
Scientists have found that 22 species of mammals – from humans to giraffes – have evolved eyelashes that are one third the width of their eye to protect from dust and moisture evaporation. 
Eyelashes shorter or longer than one third the width of the eye increase airflow around the eye and lead to more dust hitting the surface. 
“Eyelashes form a barrier to control airflow and the rate of evaporation on the surface of the cornea,” said Guillermo Amador, a Georgia Tech PhD candidate in the George W Woodruff School of Mechanical Engineering who authored the study. 
“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 funnelling air and dust particles into the eye,” Amador said. 
Amador and the reresearch team led by Assistant Professor David Hu, sent a student to the American Museum of Natural History in New York in 2012 to measure eyes and eyelashes of various animals.  Aside from an elephant, which has extremely long eyelashes, every species studied had evolved to the same ratio of lash length to eye width.  The team then built the wind tunnel to re-create air flows on a mimic of an adult, human eye. 

Source: Economic Times