The diurnal variation of intraocular pressure—the most important symptom for early detection and follow-up of the glaucomas

Hans Goldmann in 1958 emphasized the importance of the diurnal curve of intraocular pressure for very early detection of glaucoma. He stressed from the investigations of Leydhecker ( 1959 ) that there is a 10-year interval between early detection of chronic glaucoma and the first signs of neuronal defects or even later, functional problems. Roberto Sampaolesi ( 1974 ) finally has proven the important innovation from his great number of diurnal curves. Of course, a precise diurnal curve (Sampaolesi asked for eight measurements) is almost impossible by the ophthalmologist’s office or even within the hospital. We need the cooperation of the patient (like we do this in blood pressure measurement or even diabetes control). This requires an easy-to-handle “self-tonometer”, which allows measurement at any time of the day, even in different positions of the patient's body. Due to some difficult technical problems to be solved, it took until 1988 before the “automatic self-tonometer” was available. This was first tried in three space missions (Spacelab D1, 1985; Spacelab D2, 1993; German-Russian MIR-Mission 1992) allowing for the first time to register the enormous increase of intraocular and intracranial pressure after entering into microgravity. Some years later, the first instrument for clinical application was available, allowing a large series of dense diurnal curves, confirming Goldmann's and Sampaolesi's hypothesis. The technical solution, application, and results with this new instrument are described.