Add this to your list of bizarre beauty standards—the ideal eyelash length is apparently one-third the width of your eye, at least according to researchers at the Georgia Institute of Technology. For a study published in The Royal Society researchers looked at 22 species of mammals—ranging from humans to hedgehogs—to determine that this was the optimal length because it prevented dryness and protected eyes from tiny particles and debris.
While thick, long lashes might your secret flirting weapon, they may be scientifically harmful to your eye—especially if you’ve made a habit of wearing fake lashes for a more dramatic look. For the study, scientists created a machine that replicated an adult eye as air flowed toward it. As lashes grew longer, they created a cylinder effect above the cornea and air moved into the eye faster, collecting dust and causing dryness. Shorter eyelashes didn’t have such an adverse effect. However, for those with sparse lashes, fake lashes might be a safe, protective option.
“Even if they’re not the correct length, more eyelashes are always better than less,” researcher Alexander Alexeev said in a statement. But if they extend too far past one-third the width of your eye, batting your eyelashes might turn into furiously blinking away dust.