Glaucoma is characterized by irreversible vision loss through the progressive death of optic nerve fibers unless timely diagnosis and adequate treatment are provided. Medical therapy is aimed at lowering intraocular pressure (IOP) below a clinically determined target level in order to prevent or slow glaucoma progression. IOP is known to vary with the time of day as well as with daily activities.

The current way of assessing nycthemeral IOP fluctuation is to perform repeated discrete tonometry measurements, allowing only snapshot and non-continuous measurements once per hour in the best cases. The procedure is cumbersome, expensive, inconvenient (disturbed sleep cycle as patient is awoken for nocturnal/sleep period measurements) and may not detect crucial IOP values in time.

Sensimed AG has developed a new contact lens (CL)-based device intended to continuously measure IOP over 24 hours. The objective of this study is to investigate the use of device for 24-hour IOP monitoring in healthy subjects and glaucoma patients.

Inclusion Criteria:

• For Open Angle Glaucoma (OAG) subjects, a clinical diagnosis of primary OAG, including normal tension glaucoma (NTG) all known untreated IOP measurements < 22 mmHg using Goldmann Applanation Tonometry (GAT) for NTG no IOP-lowering treatment; otherwise, a 4-week wash-out period prior to the recording
• For healthy subjects, no structural defects, normal visual fields, IOP ≤ 21 mmHg and open angles on gonioscopy
• Aged ≥ 18 years, either gender
• Body Mass Index ≤ 30 kg/m2
• Central Corneal Radius (flat meridian) between 7.5 mm (45 D) and 7.9 mm (42.75 D)
• Central Corneal Thickness between 500 microns and 600 microns
• Difference in IOP absolute value between eyes within 2.5 mmHg at screening in sitting position
• Same direction of IOP variation (positive or negative) for the 2 eyes when moving from sitting to supine positions at screening
• Spherical refraction within ±6.00 diopters and cylinder refraction within ±3.00 diopters
• Having given written informed consent, prior to any investigational procedures

Exclusion Criteria:

• Ocular pathology (other than glaucoma for glaucoma subjects)
• Previous glaucoma, cataract or refractive surgery
• Corneal or conjunctival abnormality, precluding contact lens adaptation
• Severe dry eye syndrome
• Subjects with allergy to corneal anesthetic
• Subjects with contraindications for silicone CL wear
• Subjects with contraindications for Water Drinking Test (WDT) (eg., heart, renal problems)
• Subjects unable or unwilling to comply with the study procedures
• Participation in other interventional clinical research within the last 4 weeks