Sleep apnea is characterized by repetitive episodes of decreased or interrupted airflow in the upper airways during sleep. Obstructive sleep apnea syndrome (OSAS) is the most common sleep-related breathing disorder and is characterized by repeated partial or complete upper airway collapse, gasping episodes, daytime sleepiness and fatigue. Once suspected, the diagnosis is made on the basis of anamnesis and a polysomnography (PSG) using the so-called respiratory disturbance index (RDI) to grade OSAS. Standard therapy consists of continuous positive airway pressure (CPAP) during sleep to prevent upper airway collapse. The association between OSAS and glaucoma has been extensively studied, although a few reports have been non-confirmatory. OSAS has been associated with reduced ocular blood flow, leading to hypoxia and hypercapnia, and as such, may represent a risk factor for glaucomatous optic neuropathy. OSAS has also been related to loss of nycthemeral rhythm of intraocular pressure (IOP). In addition, CPAP has been reported to increase IOP when used during nighttime.

The purpose of this study is to investigate how IOP varies in time, particularly during sleep in OSAS patients with or without glaucoma, and if the IOP variations are associated with the use of CPAP. IOP fluctuations will be monitored with SENSIMED Triggerfish®, a portable investigational device using a contact lens sensor that monitors the IOP fluctuation continuously over 24-hours.

Inclusion Criteria:

• Patients with a confirmed diagnosis of moderate to severe OSAS, determined by a RDI > 15 on PSG
• Patient has either POAG with controlled IOP or no glaucoma. Five of each will included in the study
• Patients under CPAP therapy
• Aged ≥ 18 years, of either sex
• Not more than 4 diopters spherical equivalent on the study eye
• Not more than 2 diopters cylinder equivalent on the study eye
• Have given written informed consent, prior to any investigational procedures

Exclusion Criteria:

• Sleep disorders other than OSAS
• Use of sleep medication
• Patients with history of intraocular surgery (including laser therapy) within the last 3 months
• Corneal or conjunctival abnormality hindering contact lens adaptation
• Severe dry eye syndrome
• Patients with allergy to corneal anesthetic
• Patients with contraindications for silicone contact lens wear
• Patients not able to understand the character and individual consequences of the investigation
• Participation in other clinical research within the last 30 days