In different cases intraocular pressure (IOP) have to measured in lying position. Therefore a lot of portable tonometers have been established. The Icare Pro is a new tonometer on the market that allows faster and more comfortable IOP-measurements. No local anesthesia is needed, what is a major advantage for the patients. In this study the investigators want to evaluate if IOP measurements with Icare Pro Tonometer are as reliable as they are with other established portable tonometers (Perkins, TONO-Pen and hand held-Dynamic Contour Tonometer).

• Trial with medical device

Inclusion criteria:

• healthy patients of at least 18 years of age or above

Exclusion criteria:

• diagnosis of glaucoma or other optic neuropathies
• corneal disorder that make IOP measurement impossible