Long lashes may be alluring, but watch out: A new study says they funnel air into the eye rather than protect it, Today reports. Researchers started off by measuring animals' eyelashes, which were always one-third the width of the eye. Such natural lashes apparently protect against dirt and drying by creating an area of stagnant air in front of the eye. Researchers then studied synthetic lashes attached to artificial eyes made from aluminum caps filled with water, Science reports. When the lashes were natural length, they reduced particle accumulation and evaporation by half in a wind tunnel. But at longer lengths they actually funneled air into the artificial eyes, drying them out and carrying in particles like dust.
Tests haven't confirmed the same long-lash effect on women, but one doctor says she often sees dry-eye cases when mascara is used to lengthen lashes. "Dry eye is multifactorial, but I think this could be a contributing factor," she says. A corneal surgeon in Los Angeles says other, worse problems can result from eyelash extensions. Acids in the glue used to attach fake lashes can hurt the cornea, she says, and extensions can point toward the cornea and cause "corneal abrasions" when eyelashes grow out. The study, presented at the Society for Integrative and Comparative Biology, has an odd side-benefit: It may also lead to self-cleaning devices on planetary rovers and other machines. (Another study looks at why female allergies are worse.)