[Application of rebound self-tonometry for measurements in a supine position]

Diurnal or nocturnal fluctuations of intraocular pressure (IOP), which are especially common in glaucoma patients, often require hospitalization of the patient in order to be detected. This is often inconvenient for the patient. Therefore, this study evaluated the usefulness of a rebound tonometer (RT) designed for IOP self-tonometry (RT-Home) in an outpatient department, especially in the supine position and out of office hours.

Over a period of 6 months unselected open-angle glaucoma patients were equipped with a RT-home device for one night each. At the beginning IOP values measured by medical personnel (RT-Home(o)) were compared with IOP measured by the patient (RT-Home(p)), as well as measured by applanation tonometry according to Goldmann (GAT). Patients also completed a questionnaire regarding subjective comfort during use of the RT-Home.

The RT-Home(o) showed a bias of -1.1 mm Hg (-7.9 to 5.7 mm Hg) compared to GAT and RT-Home(p) showed a bias of -1.6 mm Hg (-8.9 to 5.9 mm Hg) compared to GAT. The measurement differences between GAT and RT-Home(o) as well as RT-Home(p) showed a stong correlation with the IOP and the central corneal thickness (IOP: r = 0.481, P > 0.0001, RT-Home(o) vs. GAT; corneal thickness: r = 0.612, P < 0.0001, RT-Home(o) vs. GAT). The RT-Home(p) in a supine position showed significantly elevated IOP levels than during the day (P < 0.0001). The RT-Home showed no qualitative differences between measurements in supine and sitting positions.

The RT-Home is effective and precise for use in an outpatient department to gain a general overview over patients' IOP out of office hours and also in the supine position. In the long term it seems possible that RT-Home can avoid hospitalization for diurnal and nocturnal IOP evaluation especially of young, mobile patients; however, interpretation of the data always requires professional knowledge.