Abstract
The crystalline lens and cornea comprise the eye’s optical system for focusing light in human vision. The changes in biomechanical properties of the lens and cornea are closely associated with common diseases, including presbyopia and cataract. Currently, most in vivo elasticity studies of the anterior eye focus on the measurement of the cornea, while lens measurement remains challenging. To better understand the anterior segment of the eye, we developed an optical coherence elastography system utilizing acoustic radiation force excitation to simultaneously assess the elasticities of the crystalline lens and the cornea in vivo. A swept light source was integrated into the system to provide an enhanced imaging range that covers both the lens and the cornea. Additionally, the oblique imaging approach combined with orthogonal excitation also improved the image quality. The system was tested through first ex vivo and then in vivo experiments using a rabbit model. The elasticities of corneal and lens tissue in an excised normal whole-globe and a cold cataract model were measured to reveal that cataractous lenses have a higher Young’s modulus. Simultaneous in vivo elasticity measurements of the lens and cornea were performed in a rabbit model to demonstrate the correlations between elasticity and intraocular pressure and between elasticity and age. To the best of our knowledge, we demonstrated the first in vivo elasticity of imaging of both the lens and cornea using acoustic radiation force-optical coherence elastography, thereby providing a potential powerful clinical tool to advance ophthalmic research in disorders affecting the lens and the cornea.
Highlights
The eye is a complex organ consisting of several mutually interacting components, with each part bearing biomechanical properties that are closely related to its respective anatomic functionality
An experiment based on a cold cataract model was performed ex vivo to test the proposed ARF-Optical coherence elastography (OCE) system
The corresponding Young’s moduli were calculated to be 27.4 kPa and 30.4 kPa, respectively, using Eq (3). These results demonstrate the increased Young’s modulus of the lens in the cold cataract model, which was supported by a previous study
Summary
The eye is a complex organ consisting of several mutually interacting components, with each part bearing biomechanical properties that are closely related to its respective anatomic functionality. Changes in the biomechanical properties are associated with a number of ocular diseases.. The cornea and the crystalline lens, like a Keplerian telescope, focus light onto the retina through a series of refractions, allowing us to perceive a sharp image of objects. Thereafter, the biconvex lens provides the remaining refractive power (Fig. 1). The lens can have its curvature dynamically adjusted to allow adjustment of focal distance through a process known as accommodation.. The lens loses its malleability and its dynamic range of adjustable focus evanesces. With advancing age and in many disease states, the lens becomes more rigid and more opaque and is described as a cataract.. The biomechanical properties of the lens are essential to understand the development of refractive disorders. Other disorders, including myopia, hyperopia, and astigmatism, within this optical system may cause refractive errors. In severe cases, vision quality can be significantly affected, resulting in serious reduction in quality of life
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