Ocular Perfusion Pressure Measurement

For functionality testing of the implanted microstents, OPT was applied as an existing method to quantify retinal and ciliary blood pressures as well as perfusion pressures in humans.²⁶ (link)^,27 (link) A suction cup oculopressor (Fa. B. Boucke, Medizin-Elektronik, Tübingen, Germany) approved in human medicine, consisting of a vacuum pump that is connected to the eyeball by a flexible tube, was used. The suction cup was adjusted to the anatomy of the rabbit eye as described elsewhere.²⁸ Briefly, the suction cup oculopressor was used to increase the IOP about 40 mm Hg during an examination period of eight minutes. Before IOP increase using a suction cup oculopressor, the initial baseline IOP was measured. During OPT, the IOP was measured using the rebound tonometer (Fig. 3). To record pressure decay during OPT, the IOP was measured every minute. Finally, IOP was recorded eight minutes after termination of OPT. Upon completion of a series of measurements a moisturizing gel (Vidisic; Bausch & Lomb GmbH, Berlin, Germany) was applied to the eyes. In total, OPT was performed under general anesthesia as already described above, at 4 weeks postoperatively and subsequently every 4 weeks until the end of the study.