Effects of CPAP for patients with OSA on visual sensitivity and retinal thickness

Obstructive sleep apnea/hypopnea syndrome (OSA) could compromise oxygenation of the optic nerve and cause glaucomatous optic neuropathy; there has been no study to investigate the microstructure changes of the optic nerve and retina in OSA patients before and after continuous positive airway pressure (CPAP) therapy. In this study, we assess whether treatment with CPAP might improve visual sensitivity and retinal thickness in patients with OSA. Patients with OSA were prospectively recruited and referred for ophthalmologic evaluation at baseline and three months after CPAP treatment. Each patient underwent an ophthalmological exam, standard automated perimetry (SAP), and optical coherence tomography (OCT) exam. Peripapillary retinal nerve fiber layer (RNFL) and macular layer (ML) thickness parameters were measured. The SAP, RNFL, and ML thickness parameters before and after treatment were compared. A total of 32 OSA patients were consecutively enrolled. At baseline, the mean deviation (MD) of SAP was −2.15 ± 1.90 dB (dB). After CPAP treatment, the MD was −1.38 ± 1.37 dB (p = 0.017). Regarding the OCT parameters, the inferior quadrant and nasal-inferior sector of RNFL thickness significantly improved after treatment (p = 0.025 and 0.004, respectively). The ML thickness in the superior-inner sector, inferior-outer sector, nasal-outer sector, superior hemisphere, and inferior hemisphere were also significantly improved after treatment. Improvement of ML thickness in the superior-inner sector positively correlated with the apnea/hypopnea index (r = 0.405, p = 0.022) and desaturation index (r = 0.473, p = 0.006) on pre-treatment polysomnography. The treatment of CPAP could improve visual sensitivity and increase retinal thickness in patients with OSA.