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M. A. Reilly, P. D. Hamilton, N. Ravi; Comparison of Optical Changes During Accommodation in Natural and Refilled Porcine Lenses. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3782.
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To determine the efficacy of refilling the lens capsule with a homogeneous material with properties matched with those of the natural lens.
Fresh porcine lenses were dissected, keeping the zonules and ciliary muscle attached. The lens was fixed in an eight-arm lens stretcher by clamping on the ciliary muscle. A slit-lamp microscope was used to image the lens in vitro from a position at the equator, perpendicular to the optical axis. This allowed clear visualization of the curvature of the optical zone of both lens surfaces. Radii of curvature of both surfaces were determined as a function of applied force. The experiment was then repeated with lenses refilled with a homogeneous hydrogel polymer.
The accommodative changes of the natural and refilled lenses were markedly different. The optical power of the natural lens decreased monotonically as equatorial displacement increased. The optical power of the refilled lens increased slightly due to stretching, though neither radius of curvature changed signficantly. Mechanical modeling using local material property data found using microindentation1 indicated that the variation in mechanical properties in the natural lens may be required for achieving useful accommodation in lens refilling.
The optomechanical behavior of the lens is dependent on local mechanical properties. Refilling the lens with a homogeneous material does not recover useful accommodation. Mechanical modeling of the lens as a viscous or homogeneous medium will not capture its true behavior.Reference:1. M. A. Reilly and N. Ravi, The Mechanical Properties of the Porcine Lens. Invest. Ophthalmol. Vis. Sci. 2007 48: E-Abstract 2023.
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