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Rebound self-tonometer shows reliability in measuring IOP
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Self-monitoring of IOP with the Icare Home tonometer proved manageable and accurate in a study.
Measurements were comparable to those performed by an ophthalmologist using the same device and standard Goldman applanation tonometry (GAT).
A total of 130 subjects with suspected or confirmed glaucoma were included. After detailed instructions, 98% of them were able to use the Icare Home device correctly.
Three consecutive IOP measurements were taken in each eye in an office setting, first by an ophthalmologist and then by the patients. These measurements were then compared with GAT measurements taken 5 minutes later. In all the participants, central corneal thickness (CCT) was measured by ultrasound pachymetry.
No significant difference was found between the mean IOP measured with the Icare Home by the patient and by the ophthalmologist, while some difference was found in about half of the patients between Home and GAT measurements. In the majority of these cases, Home tonometry showed a tendency to overestimate IOP, and this occurred more frequently in eyes with higher CCT values.
As the authors noted, “self-tonometry is a valuable option for recording out-of-the-office IOP because the IOP fluctuates both within and across days.”
The Home Icare tonometer is a handheld device that uses the induction-based rebound method and does not require topical anesthetics. Each measurement sequence includes six measurements, on the basis of which the tonometer provides the final IOP measurement. Results are stored with the date and time and can be viewed on a personal computer, using a dedicated software. – by Michela Cimberle
Disclosure: The authors reported no conflict of interest
Perspective
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Derek MacDonald, OD, FAAO
One of the most challenging aspects of glaucoma management is caring for patients who progress despite having IOPs that appear to be at target. Assuming that these patients are adherent to treatment and not just taking their drops before their appointments, progression means that the target pressure is too high, right? Well, while that may be true in some cases, keep in mind that measuring IOP every few months samples only a few seconds (usually between 8 a.m. and 6 p.m.) out of the nearly 32 million that comprise a year. Even obtaining multiple measurements at different times of the day, we’re working with very limited and perhaps poorly representative data.
Takagi and colleagues have demonstrated that nearly all patients with good acuity and binocularity are able to reliably self-assess IOP. Although not directly comparable to in-office measurement, the true value of home tonometry may lie in the identification of IOP spikes occurring outside office hours, a pattern that may be the rule rather than the exception.
Despite making great strides in understanding disease pathophysiology and diagnosis, manipulating and monitoring IOP remains a cornerstone of management. A more comprehensive dataset is an overdue and welcome addition.
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