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Maja Maria Rogala, Monika Ewa Danielewska, Agnieszka Antonczyk, Zdzislaw Kielbowicz, Jerzy Detyna, Robert Iskander; Investigation of corneal pulse response to artificial increase in intraocular pressure in rabbit eyes. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3144.
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© ARVO (1962-2015); The Authors (2016-present)
Ocular dicrotic pulse (ODP) was observed among glaucoma patients and its origin remains unknown. We performed a clinical study to assess changes in time and spectral parameters of the corneal pulse (CP) signal leading to ODP after monitored short-term artificial increase of intraocular pressure (IOP) in rabbit eyes. We hypothesized that the increased level of IOP should alter the characteristic of the CP signal.
Eight New Zealand white rabbits (3.5–4.5 kg) aged 6 months were used in the experiment. Each animal was anaesthetized and underwent simultaneous recordings of IOP, CP, blood pulse (BP) signal and intra-arterial blood pressure (IBP). All the measurements were obtained at natural (baseline) or short term elevated IOP conditions (up to 90 mmHg). Invasive manometric method was employed for continuous IOP recording by inserting injection needle into anterior chamber of the eye. The CP signal was acquired in non-contact manner with ultrasonic transducer placed in front of the right eye synchronically with BP signal registered with pulse oximeter placed on animal ear artery. To obtain precise IBP data, the central auricular artery was catheterized. Raw data were numerically processed to estimate time and spectral parameters of CP signal.
At baseline IOP condition, no significant correlations were found between IOP level and CP parameters represented in time and spectral domains. Elevated IOP conditions showed that IOP statistically significantly differentiate only the power of the first frequency harmonic of the CP signal (Kruskal-Wallis, p=0.031). Furthermore, there was a significant difference in mean, diastolic and systolic arterial pressure with the IOP levels (Kruskal-Wallis, p=0.025, p=0.019, p=0.033, respectively).
Elevated IOP was found to differentiate CP spectral distribution rather than its time domain parameters. Corneal response induced by elevated IOP reflects in changes in lower frequency component of the CP signal related to the blood pulse. We conclude that acute increase in IOP does not alter the higher harmonics of CP components, which are responsible for the ODP formation. Further investigation of the relation between CP and long term elevated IOP as well as corneal biomechanics should be conducted.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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