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IOP taken with contact lens sensor correlates with visual field changes
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Researchers determined that the use of 24-hour IOP measurements obtained via a contact lens sensor were associated with the rate of visual field progression in patients undergoing treatment for glaucoma.
De Moraes and colleagues evaluated 34 patients between the ages of 40 and 89 years being treated for primary open-angle glaucoma and whose IOP measured 20 mm Hg or less. Patients had at least eight visual field tests performed within at least 2 years of follow-up.
Subjects wore the Sensimed Triggerfish wireless contact lens sensor and were evaluated for rates of visual field mean deviation change before and at the time of the IOP recording and the sensor parameters, including number of large peaks, mean peak ratio, wake-to-sleep slope, amplitude and area under the cosine curve, and variability from the mean, according to the study.
“When comparing the rate of mean deviation change before and at the time of contact lens sensor recording of all patients, the average slope was 0.05 dB/year faster in the beginning compared with the end (P = 0.087), suggesting a deceleration of progression by the time of contact lens sensor recording,” the researchers wrote. “The number of long peaks and the mean peak ratio when patients were awake were the best predictors of faster progression.”
They concluded that IOP parameters obtained with the 24-hour recording with the Triggerfish device were associated with the rate of visual field progression in these subjects.
“A combination of contact lens sensor parameters obtained during a single 24-hour session provides a signature that seems to explain the rate of glaucoma progression better than a summary of office-hour IOP measurements in multiple visits,” they said. – by Nancy Hemphill, ELS, FAAO
Disclosures: De Moraes is a consultant to Sensimed. Please see the full study for all authors’ financial disclosures.
Perspective
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Blair Lonsberry, OD, FAAO
Intraocular pressure remains the only modifiable risk factor for glaucoma and glaucoma progression.
Monitoring a patient’s IOP is challenging, as single readings are typically obtained during working hours. Measuring IOP over a 24-hour period is time consuming and challenging.
The purpose of this study is to determine if a continuous 24-hour IOP recording can provide information that correlates to the rate of visual field change at the time of monitoring. Utilizing a wireless contact lens sensor (CLS) allowed the authors to obtain a 24-hour IOP-related recording for patients who had varying glaucoma progression rates.
The authors determined that a combination of CLS parameters (e.g., number of large peaks and mean peak ratio when patients are awake) provided better measures than Goldmann IOP parameters (mean, peak and fluctuation) in the same period with respect to visual field progression.
When treating patients with glaucoma, clinicians try to obtain as much information with respect to IOP and fluctuation as possible. This study has limitations (small sample size, the CLS is not the same measure as Goldmann, changes in patients’ treatment protocols, etc.) but does seem to demonstrate that obtaining a 24-hour measure of a patient’s IOP can predict potential glaucomatous progression.
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