Corneal biomechanical properties in obstructive sleep apnea syndrome

Objectives: To investigate the corneal biomechanical properties and anterior segment parameters in patients with obstructive sleep apnea syndrome (OSAS). Methods: Fifty-four eyes of 54 patients with OSAS and 20 eyes of 20 healthy subjects were included. Patients with mild and moderate OSAS (Respiratory Disturbance Index [RDI] <30) enrolled in group 1, those with severe OSAS (RDI>= 30) in group 2 and controls in group 3. Corneal biomechanical properties including corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc) were measured with ocular response analyzer. Maximum (Kmax), minimum (Kmin), and mean simulated (SimKm) keratometry values, corneal astigmatism (CA), and central corneal thickness (CCT) were evaluated with Pentacam Scheimpflug imaging. Results: The mean CH and CRF were significantly lower in group 2. The mean CH was 10.9 +/- 1.4 mm Hg in group 1,10.1 +/- 1.1 mm Hg in group 2, and 12.1 +/- 1.2 mm Hg in group 3 (P<0.001). The mean CRF was 11.1 +/- 1.8 mm Hg in group 1, 9.9 +/- 1.1 mm Hg in group 2, and 12.2 +/- 1.2 mm Hg in group 3 (P<0.001). The CH and CRF values were similar between the groups 1 and 3 (P = 0.867 and P = 0.743). Corneal-compensated intraocular pressure, IOPg, Kmax, Kmin, SimKm, CA, and CCT values were not statistically different among the three groups. Conclusions: Patients with severe OSAS had lower CH and CRF values. The lower CH and CRF values in the severe group were possibly related to changes of the structural properties in the cornea.