[Principles of measurements in tonometry at the time of Albrecht von Graefes to D2 mission and self-tonometry].

There is no doubt that an elevation of intraocular pressure (IOP) precedes any morphological or functional glaucomatous damage for years, if not decades. Surprisingly, in the present glaucoma literature methods for a quantification of such a damage are prevailing. There might be two reasons for this: The question of tonometry is supposed to be perfectly and definitely solved or tonometry as the most significant diagnostic tool for an early diagnosis of glaucoma has been lost out of sight. Two aspects shall be discussed in the following: Firstly, we want to deal with an improved glaucoma management especially in the early phase of the disease. The question is when and how often should tonometry be performed to detect the typically greater diurnal fluctuations of IOP in glaucoma. This has already been pointed out in particular by Sampaolesi and Hager. Secondly, the technique of the most appropriate tonometer for this purpose is outlined. Important aspects are the accuracy of the instrument according to the standard set by the Goldmann applanatation tonometer as well as safety and easy handling. Like in other branches of medicine where the patient is more and more involved in his own disease control (eg self-measurement of blood pressure in patients with arterial hypertension), self-tonometry is likely to become a revolutionary step towards an improved management and follow-up of glaucoma. These are the objectives we should concentrate on. Technical solutions, clinical applications and experiences are demonstrated.