Self-tonometry with a Telemetric Intraocular Pressure Sensor in Patients With Glaucoma

Background: Accurate acquisition of intraocular pressure (IOP) data, particularly short-term and long-term fluctuations, plays an important role in the medical care of glaucoma patients. Non-invasive self-tonometry with a telemetric IOP sensor can provide important data on the individual IOP profile. Methods: Within the framework of a prospective, single-centre pilot clinical trial, a ring-shaped telemetric IOP sensor was inserted into the ciliary sulcus after implantation of the intracapsular lens during planned cataract surgery. In accordance with the protocol, at the 5-month visit, all patients received a reading unit for one-month self-tonometry assessment. All patients were asked to measure the IOP at least once daily, and, if possible, at many different times. The first IOP measurement of each day was evaluated (covering one measurement daily per patient on 20 different days within the assessment interval). Furthermore, IOP data were analysed according to the time of day, divided into early phase (5 am to 11 am), midday (11 am to 4 pm) and late phase (4 am to 11 pm) (patients with at least 10 measurements and max. 20 measurements were included). Descriptive statistics of the original ARGOS system values were calculated, with evaluation of the percentiles and presentation in box plots. Results: All patients successfully performed self-tonometry at home after receiving brief instructions. The first IOP measurement of each day covered a very wide interindividual range (between 3.1 mmHg in patient 5 and 21.7 mmHg in patient 4). Analysis of IOP values by time of day showed that patient 1 had significantly higher IOP values in the late day phase. For patient 5, the highest values were at midday. Patients 3 and 4 showed no significant fluctuations during the day. Conclusions: Self-tonometry encourages patients to be actively involved in the management of their own illness and allows non-invasive assessment of IOP at different times and during diverse activities. However, the analysis and interpretation of these new data require further study, especially in relation to Goldmann applanation tonometry.