Eye Vessel Compliance as a Function of Intraocular and Arterial Pressure and Eye Compliance

Abstract

Age-related macular degeneration (AMD) is a disease affecting the eye and is likely related to an increase in eye vascular rigidity. Developing methodologies to measure eye vessels compliance is of interest, as this may prove useful in diagnosing retinal diseases such as AMD. In vitro and in vivo experiments were conducted on rabbit eyes to validate the methodology proposed. Therefore the compliance of the eye vessels was estimated indirectly from the measurements of intraocular pressure (IOP), blood pressure and the compliance of the eyeball (OC) and compared to the pressure-volume curve. The method to estimate the vascular compliance of the eye was then tested under normal conditions and after administration of norepinephrine in vivo, which induced a vasoconstriction leading to reduction in vascular compliance. In vitro comparison of direct versus indirect estimates of compliance showed a difference that was not significant (0.075 vs. 0.077 μl/mmHg, p = 0.86). Results from the in vivo study indicated that norepinephrine significantly increased the arterial pulse pressure amplitude while compliance of vascular network of the eye decreased from 0.18 ± 0.12 μl/mmHg to 0.10 ± 0.08 μl/mmHg (p = 0.001). These results indicate that the compliance of the vascular network can be predicted using the IOP, the arterial pressure and the OC of the eyeball.