Effect of Obstructive Sleep Apnea on Corneal Morphological Characteristics

To determine central corneal thickness (CCT) and the corneal parameters in patients with obstructive sleep apnea (OSA), evaluate the relationship between the severity of OSA, minimum peripheral capillary oxygen saturation (min. SpO2), and corneal morphological characteristics.

Patients with OSA diagnosed by full-night polysomnography before treatment were included. Patients with OSA were divided into 3 groups according to the Apnea-Hypopnea Index (AHI). The control group (CG) was examined to exclude the possibility of OSA and ocular diseases. The following data were recorded: age, sex, body mass index, ophthalmologic evaluation, and the results of polysomnography.

A total of 114 eyes were studied: 74 eyes of patients with OSA and 40 eyes of the CG. The mean age was 57 ± 6 years. The mean values of CCT and endothelial cell density (ECD) varied significantly between the patients and the CG (P < 0.001). The mean values of CCT, ECD, cell variation coefficient (CV), and hexagonal cell percentage (HEX) in the group of patients with OSA were 535.28 ± 21.32 μm, 2632 ± 333, cells/mm. 31.8 ± 3.9, and 55.6 ± 6.9%, respectively. The mean CCT and ECD values for each group were lower than those for the CG. A significant negative correlation was found between CCT and ECD for AHI values (r = -0.390, P = 0.011 and r = -0.109, P = 0.040, respectively), and a weak positive correlation between CCT and ECD was found for min. SpO2 (r = 0.282, P = 0.020 and r = 0.332, P = 0.018, respectively). CV and HEX did not significantly differ between the groups and did not correlate with the results of polysomnography.

Hypoxia is associated with significant changes in CCT and ECD. In patients with OSA, these parameters varied significantly when compared with the subjects in the CG. The severity of hypoxemia and the increase in AHI values reduce CCT and ECD in patients.