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Mansouri and colleagues recently reported the results of a prospective study in which 33 subjects (31 healthy and two with primary open-angle glaucoma) underwent observation during a 24-hour period while wearing a Triggerfish contact lens sensor in one randomly selected eye and undergoing every-two-hour pneumatonometry in the fellow eye with the specific goal of validating the Triggerfish system's ability to detect changes in intraocular pressure (IOP) known to occur during the wake to sleep transition and its ability to infer heart rate based on ocular pulse frequency. The investigators' larger goal was to demonstrate that the Triggerfish device can identify known physiologic IOP behavior, and thus can be useful in assessing IOP in the clinical setting of glaucoma care.
The clinical significance is that this device can be used to infer the nature of IOP behavior outside office hours, including the critical time during sleep when IOP is highest
The device has already been shown to detect large acute changes in IOP associated with blinks and saccades. The current study demonstrates the ability of Triggerfish to detect small changes in IOP that may be more relevant to the magnitude of IOP changes that we might be interested in during clinical 24-hour IOP monitoring. These data, in combination with other published studies, demonstrate that the Triggerfish device can provide relevant information regarding IOP behavior. The clinical significance is that this device can be used to infer the nature of IOP behavior outside office hours, including the critical time during sleep when IOP is highest. Further, as the importance of ocular perfusion pressure (OPP) - particularly nocturnal OPP - continues to become apparent in glaucoma, this device provides the means of collecting 24-hour IOP data which, when paired with 24-hour ambulatory blood pressure monitoring, can provide a valid representation of circadian OPP without the need for overnight evaluation in a clinical research facility. The epidemiologic importance of OPP and glaucoma prevalence has been well established in cross-sectional studies. Coupling Triggerfish with ambulatory blood pressure monitoring provides a mechanism for conducting longitudinal studies evaluating the relationship between OPP and glaucoma progression risk.