[Diurnal variation of ocular pressure in open-angle glaucoma with telemonitoring]

Abstract

Background: The aim of this study was to study and analyse distribution, range and intraday variation of ocular perfusion pressure (OPP) in patients with primary open-angle glaucoma (POAG) in the framework of telemedical home-monitoring.

Methods: In the project Teletonometry Mecklenburg-Vorpommern (TTMV) patients were equipped with a home-monitoring system for self-measurement of intraocular pressure and blood pressure. All measurements were transmitted via telephone modem to an electronic patient record that automatically calculated OPP. We present the temporal characteristics of OPP in 70 patients with POAG. After the measurement of blood pressure and intraocular pressure was performed, the individual ocular perfusion pressure was calculated by the formula: (OPP=[2/3 x (2/3 x DBP + 1/3 x SBP)]-IOP).

Results: In 3282 OPP measurements the percentage of values less than 50 mmHg was: left eye 2273/69.2%--right eye 2362/71.9 % and less than 40 mmHg: left eye 687/20.9 %--right eye 794/24.2%. 50/51 (left eye/right eye) patients had an individual OPP average of less than 50 mmHg and 10/10 (left eye/right eye) patients less than 40 mmHg. The diurnal OPP trend showed 4 phases (7-12, 12-18, 18-22, 22-7 hour). In the intervals from 22-7 hour and 7-12 hour ocular perfusion pressure values were low. Between 7-12 hour ocular perfusion pressure was significantly depressed as in the other phases (p<0.05).

Conclusions: Ocular perfusion pressure of glaucoma patients calculated using intraocular pressure (self-tonometry) and blood pressure demonstrates a feasible method to evaluate individual diurnal OPP fluctuations. However, this OPP could be described a bit more precisely as the really topical ocular perfusion. Many physiological conditions may not be included, e. g., autonomic circulation. Simultaneous measurement of blood pressure and intraocular pressure enable the detection and analysis of side effects and interactions between glaucoma and hypertension therapy. In clinical practice OPP telemonitoring presents a new way to examine ocular blood circulation in routine glaucoma work-up. The diurnal OPP variations were associated with the fluctuations of systemic blood pressure for the most of part.