Chalkiadaki E, Andreanos K, Florou C, et al. - In this prospective, comparative case series, researchers examined central endothelial cell density (ECD), morphology, and central corneal thickness in patients newly diagnosed with severe obstructive sleep apnea-hypopnea syndrome (OSAHS) and explored the association between these parameters and OSAHS severity. This investigation was performed in a university ophthalmology clinic. A total of 51 patients recently diagnosed with severe OSAHS (apnea-hypopnea index above 30) and a paired, age and sex-matched control group of 44 healthy people were recruited. In total, 190 eyes were examined: 102 eyes of patients with severe OSAHS and 88 eyes of the control group. In comparison with healthy subjects, greater pleomorphism and polymegathism of corneal endothelium were observed in patients with severe OSAHS. Increases in corneal thickness can be caused by a low percentage of REM sleep, usually seen in patients with OSAHS.