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  • Nonhuman Primates’ IOP Rises in Response to Stress

    By Jean Shaw
    Selected By: Henry D. Jampel, MD, MHS
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    Journal Highlights

    Ophthalmology Glaucoma, July/August 2019

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    In an experimental study involving three nonhuman primates, Turner et al. set out to quantify the effect of stress on intraocular pressure (IOP). They found that the animals’ IOP increased rapidly and significantly in response to a stress-inducing activity.

    The researchers evaluated three male rhesus macaques between 4 and 6 years of age. They used a wireless telemetry system to continuously record bilateral IOP, aortic blood pressure, and heart rate before, during, and after the animals were given an intramuscular injection of an anesthetic. The experiment was repeated four times at least two weeks apart in each animal.

    Data were collected at six points in time: 1) at baseline, before a techni­cian approached the anteroom to the animals’ holding room, 2) when the animals could hear, but not see, the technicians entering the anteroom, 3) when the technician entered the holding room, 4) while the animal was restrained in preparation for the injec­tion, 5) immediately after the injection, and 6) 30 seconds after release of the restraint. Baseline IOP was determined by averaging two minutes of contin­uous IOP data before the technician approached the animals’ space.

    Results showed that the animals’ IOP, mean arterial pressure, and heart rate increased by 27%, 38%, and 34%, respectively, in anticipation of the injection. Within 10 seconds of the animals hearing the technician enter the outer anteroom door, their IOP increased approximately 10%, and it reached its maximum within approx­imately 1 minute of first anticipating human contact. After release of the restraint, arterial pressure and heart rate remained elevated, while IOP decreased.

    Previous studies in humans have documented rises in blood pressure and IOP when patients are anxious or stressed. However, as those studies used snapshot measurements that required subject contact, no precontact base­line could be established, and the time course of IOP change could not be as­sessed. Thus, for a fuller picture of the impact of stress on IOP, measurement technologies that don’t require interac­tion with the patient are needed.

    The original article can be found here.