Purpose: To characterize the real-time intraocular pressure (IOP) and ocular pulse amplitude (OPA) responses to controlled increases in intracranial pressure (ICP) and mean arterial blood pressure (MAP). Methods: Simultaneous recordings of the intraocular, intracranial and arterial pressure changes were performed in urethane anesthetized Sprague-Dawley rats. Pressure changes were measured using solid-state micro-sensor catheters (Scisense) inserted into each compartment. Controlled elevations in ICP and MAP were simulated by a cranial ventricular saline infusion (20 μl / minute over 10 minutes) and an intravenous vasopressor agent (phenylephrine 50 μg / kg / min over 2 minutes) respectively. Results: Simulations of transient systemic hypertension (MAP increase of 31 ± 6.3 mm Hg, n = 9) resulted in instantaneous increases in both IOP and ICP. (1.3 ± 0.4 mm Hg and 3.7 ± 0.8 mm Hg respectively, P < 0.05). Using our intracranial ventricular saline infusion protocol, a maximal increase in ICP from baseline of 9 ± 1.2 mm Hg (n = 7) was achieved. The increase in ICP was accompanied by a trend increase in IOP (0.4 ± 0.2 mm Hg, although it did not reach statistical significance (P = 0.07). There was no significance change in the OPA measured during baseline and during the ICP or MAP challenge. Conclusion: IOP is influenced by short-term physiological fluctuations in MAP and to a lesser extent by fluctuations in ICP. Further research is required to evaluate whether chronic elevations in MAP and ICP may have clinically significant influences on IOP and OPA.
Li, J., Gupta, V. K., You, Y., Ng, K., & Graham, S. (2013). Evaluation of real-time intraocular pressure and ocular pulse amplitude during acute systemic and intracranial hypertension. Clinical and Experimental Ophthalmology, 41(Supplement 1), 136-136. https://doi.org/10.1111/ceo.12232