Effect of Continuous Positive Airway Pressure Given as Treatment for Obstructive Sleep Apnea on Central Corneal Thickness: Results at 12 Months

Abstract

Background: To examine the effects of continuous positive airway pressure (CPAP) therapy on central corneal thickness (CCT) in patients with obstructive sleep apnea (OSA) followed for 12 months. Methods: Participants were patients with OSA and an indication for CPAP who were enrolled after diagnosis and graded according to the apnea hypopnea index (AHI) determined in an overnight polysomnography. Each subject underwent a full ophthalmologic examination including ultrasound pachymetry (USP) with an SP3000 USP (Tomey Inc) at the time points just before CPAP onset, and after 3 and 12 months of CPAP treatment. Results: The study sample comprised 40 eyes of 20 patients. Adherence to CPAP was adequate (5.23 ± 1.77 h/night). After receiving 12 months of CPAP, positive correlation was observed between hours of CPAP use and CCT (r = 0.382, p = 0.015). Intermittent hypoxemia pre-CPAP or hypoxia severity pre-CPAP were also positively correlated with the CCT recorded after 12 months of CPAP (r = 0.394, p = 0.012; r = 0.324, p = 0.041). Significant correlations were, however, not observed after only 3 months of CPAP treatment. In addition, compared to measurements at 3 months, intraocular pressure was higher after 12 months of treatment. Conclusions: Our findings indicate that 12 months of correct adherence to CPAP are needed to detect significant CCT thickening, and that the greater the pre-CPAP hypoxemia, the greater the capacity for an increase in CCT to be produced in response to 12 months of this therapy.