Floppy eyelid syndrome is an eyelid disorder characterized by laxity of the upper eyelids, which leads to their spontaneous flapping. A Loyola Medicine study found that 53% of patients with obstructive sleep apnea had lax and rubbery upper eyelids. Of the 35 patients suspected of having sleep apnea, 32 had a confirmed diagnosis, and 17 (53%) of them had a lax eyelid condition. The most severe cases of sleep apnea were associated with the most prominent manifestations of droopy eyelids, although this association was not statistically significant. Obstructive sleep apnea affects an estimated 34% of men and 17% of women, while up to 80% of cases remain undiagnosed. According to a 2010 Harvard Medical School study, moderate to severe sleep apnea is associated with $115 billion in health care costs. The eyelids can be lax in association with three conditions: eyelid laxity, eyelid laxity syndrome (plus conjunctivitis), and mobile eyelid syndrome in obese young men. Researchers emphasize the obligation of ophthalmologists to identify this syndrome in order to detect the risk of sleep apnea.[1][2]