Parameters Affecting Performance of Extruded-Gel-Interface Accommodating IOL
Characterize the parameters affecting the optical and mechanical performance of an extruded gel interface accommodating intraocular lens.
Measurements of actuation force, lens power, interface contour, optical transfer function, and visual Strehl ratio were made on a first generation prototype lens. A finite element analysis model was utilized to accurately predict the prototype's behavior. Analysis of the altered wavefront created by the predicted accommodating interface was completed to determine the visual OTF and visual Strehl ratio. Parameters such as aperture diameter, gel thickness, elastic modulus, Poissonís ratio, refractive index, and actuation pressure were systematically varied in the model and the resulting optical performance of the lens was predicted by pressure requirement, dioptric power, visual OTF and Strehl ratio.
The model accurately predicted the measured oblate aspherical interface which produced a diminished visual Strehl ratio. Parameters which maximize optical performance include: minimal extrusion diameter to gel thickness ratio, minimum Poissonís ratio, minimum extrusion, and maximum refractive index change at the interface. Mechanical performance optimization includes: Minimum Youngís modulus and maximum refractive index change.
Parameters which optimize optical performance were those which minimize asphericity and actuation pressure. The design prototype performs well for the present level of development. The competing nature of design parameters pose a challenge for design optimization, but this is a first step in producing a usable extruded gel interface lens.