Background. The aim of this study is to present a method of lid laxity evaluation and investigate whether there is an association between floppy eyelid syndrome (FES) and body mass index (BMI) in sleep apnea syndrome (SAS) patients compared to normal subjects. Method. A total of 135 participants (81 patients with SAS and 54 normal subjects) had a full ophthalmologic examination. The presence of FES was estimated in relation to SAS and BMI. Results. The floppy eyelid was characterized "hyperelastic," "FES stage 1 (asymptomatic)," or "FES stage 2 (symptomatic)" depending on its laxity capacity. Hyperelastic floppy eyelid in SAS patients was statistically significant (P < 0.05) when compared to normals. Similarly, the presence of hyperelasticity in high-BMI SAS patients was also statistically significant (P < 0.05) when compared to low-BMI SAS patients. Floppy eyelid syndrome was more frequent in SAS patients than in normal subjects (P < 0.05), but no association was found between FES and obesity (P > 0.05). Conclusion. A classification of FES is proposed based on lid laxity. In addition to this, our data suggests a clear association of hyperelasticity and FES to SAS patients but no association between obesity and FES.