Purpose:
IOP is the most common independent risk factor for development and progression of glaucoma, but very little is known about the dynamics of IOP. We used IOP telemetry and time synced, close-up video to characterize the fluctuations of IOP due to blinks and saccades in an awake, unrestrained non-human primate.
Methods:
We have adapted a proven implantable telemetric pressure transducer system to monitor IOP by integrating the transducer into a orbital wall-mounted baseplate that is connected to the anterior chamber via a silicone tube. The total implant system is surgically implanted and all components are internal to the animal. The implanted transmitter sends 500 IOP, ECG and body temperature measurements per second to an external antenna, and the system compensates for barometric pressure in real time. The continuous IOP signal was time synced to a close up video of the animals face. Blinks and saccades were identified in the video, and the associated IOP fluctuations were recorded.
Results:
IOP fluctuates as much as 10 mmHg day-to-day and hour-to-hour when measured continuously via telemetry in unrestrained, awake non-human primates. Blinks induced IOP spikes of 3-12 mmHg with an average duration of 150 ms. Saccades induced IOP spikes of 3-7 mmHg with an average duration of 120 ms.
Conclusions:
We have successfully measured IOP continuously using a new, fully implantable IOP telemetry system that has demonstrated high accuracy and low drift (<3 mmHg/mo). IOP fluctuates tremendously in the non-human primate, and includes IOP spikes of significant magnitude associated with eye movement and blinks. In addition, IOP fluctuations of this magnitude could be an important yet unknown contributor to IOP-related glaucomatous damage.
Keywords: intraocular pressure