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Simon Bello, Christopher L Passaglia; Intraocular Pressure Dynamics in Brown Norway Rats Measured by Telemetry. Invest. Ophthalmol. Vis. Sci. 2016;57(12):6454.
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© ARVO (1962-2015); The Authors (2016-present)
Intraocular Pressure (IOP) dynamics in rats are still somewhat unknown. In this work we present continuous monitoring of IOP in rats, which is an essential parameter in glaucoma research.
IOP was monitored using a previously described implantable system developed in our laboratory. Two different techniques were used for sensor implantation. In the first version, the sensor was attached to a jacket worn by the animal and connected to the eye using a multiple-tubing system. The second one was devised by attaching the sensor to a head mount system that coupled with a small cannula inserted in the anterior chamber. Similarly, Two versions of the system were developed, the first one was battery powered and was used to test the ability of the sensor to record IOP. The second version was wirelessly powered by using radio frequency (RF) energy transfer. The sensor was programmed to record DC changes in IOP by obtaining 20 data points at 50Hz every 20 seconds and recording their average. Alternatively, the system was used to record IOP in anesthetized rats at a rates of 300Hz, 500Hz and 1000Hz for short periods of time to determine amplitude of IOP changes due to ocular pulsations. Rats were kept in a 12-h light/dark cycle and software was used to perform statistical analysis of the IOP data.
The system has successfully recorded IOP in fully awake rats for a week to date. During the light cycle IOP had a mean value of 13.24mmHg, with a standard deviation of 2.07mmHg. On the other hand, mean IOP during the night was in the order of 16.89mmHg, with a standard deviation of 2.25mmHg. It was observed that IOP exhibited an upward trend after the first couple of days after surgery, perhaps due to healing of the implant wound. No ocular pulsations were apparent during high frequency sampling of IOP in anesthetized rats.
According to our data, brown Norway rats exhibit circadian rhythms in IOP similar to those previously reported in other species, where IOP increases with the onset of the night cycle and decreases once again during day time.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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