TOKYO — Clinicians might soon be able to distinguish between a healthy eye and one with glaucoma using the ocular equivalent of a Holter monitor, according to a new study.
Investigators used the Triggerfish contact lens sensor, from Sensimed, to analyze fluctuations in intraocular pressure patterns over 24 hours. They identified monitoring parameters that can be used to predict which eyes are healthy and which have primary open-angle glaucoma.
"With these algorithms, we have the discriminative power to distinguish between healthy and glaucomatous eyes. I hope that, in the future, we will be able to distinguish between different diseases states," said investigator René Goedkoop, MD, chief medical officer at Sensimed AG in Geneva.
Dr. Goedkoop presented the results here at the World Ophthalmology Congress 2014.
24/7 Pressure Readings
The investigators evaluated changes in intraocular pressure over time in 1 eye of 87 healthy volunteers not matched for age and in 209 patients with primary open-angle glaucoma, some of whom had normal-tension glaucoma.
All participants wore the lens sensor for 24 hours, which measures changes in ocular volume at the corneoscleral junction and expresses them in arbitrary units so that trends over time can be measured.
The investigators identified 14 parameters related to intraocular pressure patterns from the readouts, including overall variability, the number and amplitude of pressure spikes or peaks, and changes as the patients transitioned from waking to sleeping states, and vice versa.
On unadjusted univariate analysis and analysis adjusted for age and sex, 10 of the 14 parameters were significantly different between healthy and glaucomatous eyes.
Overall, the contact lens sensors had a 78% probability of discriminating a healthy eye from one with glaucoma, with 74% sensitivity and 78% specificity.
The device accurately detected glaucoma in about 75% of patients with primary open-angle glaucoma, despite the fact that the majority of these patients were on intraocular pressure-lowering drugs and some had undergone laser therapy or glaucoma filtration surgery, Dr. Goedkoop reported.
The investigators are currently testing the validity of their monitoring approach using an age-matched control group, and plan to develop algorithms to help clinicians distinguish between disease states, such as when patients convert from ocular hypertension to frank glaucoma, and between slow progressors and fast progressors, he explained.
These results add to our understanding of daily variations in intraocular pressure, but more research is needed, said session moderator Paul Kaufman, MD, chair of the Department of Ophthalmology at the University of Wisconsin School of Medicine and Public Health in Madison.
"There is a lot of work being done to answer the question of whether diurnal variation — fluctuation in intraocular pressure during the day and night — is part of the risk that makes a glaucoma patient progress," said Dr. Kaufman, who was not involved in the study.
"There are some people whose pressures really do have spikes — sometimes quite substantial — in the middle of the night. We don't have great ways of measuring that. It's not very practical to wake the patient up and get them to sit at a slit lamp and use a tonometer or whatever you're going to use. But this sensor, as sophisticated as it is, is a relatively crude kind of device for measuring fluctuation," he told Medscape Medical News.
The study was funded by Sensimed. Dr. Goedkoop is chief medical officer for the company. Dr. Kaufman has disclosed no relevant financial relationships.
World Ophthalmology Congress (WOC) 2014: Abstract FP-TH-11-3. Presented April 3, 2014.
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Cite this: Contact Lens Sensor Predicts Glaucoma From Pressure Patterns - Medscape - Apr 15, 2014.