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The Goldmann applanation tonometer is a wonderful instrument: elegant and ubiquitous, it has permitted the diagnosis of millions of patients with glaucoma and the development of effective medication to prevent or delay vision loss in many among them. Yet its use is restricted to the ocular examination room, on a sitting subject, which renders night IOP-recording impracticable and casts doubts on the reliability of measurements performed on patients aroused from sleep and rising from a supine to a sitting position. This, in turn, has resulted in significant controversies on the role of circadian IOP fluctuations on disease development and progression, and many of us have dreamt of a reliable 24-hour 'IOPHolter' to better assess our patients and optimize their treatment. Can it be that this dream has come true? In their paper, Mansouri and Shaarawi (130) describe their findings with such a device on a cohort of 15 progressive glaucoma patients. The device consists of a soft contact lens equipped with a strain gauge and a microchip which can measure and transmit data to a circular antenna applied around the eye, even through closed eyelids. With the exception of one patient with dry eye disease who could not tolerate the lens for more than 12 hours, the overall tolerability was good (average self-graded comfort score was 7 on a 0-10 scale), and the adverse events were limited: one corneal erosion in the dry-eye patient and 4 causes of superficial punctuate keratitis.
The recorded pressure curves are impressive: In 144 sixty-second measurements taken every ten minutes around the clock, one can easily identify ocular pulsations, transient IOP-spikes due to blinking, as well as significant IOP changes between the standing and sitting positions. In 69% of the patients the highest IOPs were recorded during the night (undetectable by office-based tonometry) while prolonged peaks were observed in 80% of the patient sample, mostly during the night. It is interesting to note that the investigators felt compelled by the data to change treatment in two-thirds of the patients.
Continuous IOP-monitoring is an immense opportunity to better diagnose glaucoma and individualize treatment
As the authors acknowledge, this is an initial clinical assessment of a new device which will require further experimental validation, but there is no doubt that continuous IOP-monitoring will provide an immense opportunity to better diagnose glaucoma and to optimize its management, one step nearer to individualized treatment