<qa>  What is the main advantage for the patients?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. 