Semi-aspherical Ophthalmic Lens Coma Aberration Balancing
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Solution Overview
Problem
Conventional ophthalmic lenses with aspherical surfaces are sensitive to tilt and decentration, leading to increased coma aberrations and reduced image quality, as they fail to effectively balance coma aberrations when misaligned with the optical axis of the eye.
Innovation Solution
An ophthalmic lens with a semi-aspherical surface profile, defined by the equation z(x) = cx^2 + 1 - c2*x^2 + a4*x^4 + a6*x^6 + a8*x^8, where the inner region is substantially spherical and the outer region is aspherical, which balances coma aberrations and maintains diffraction-limited image quality when centered, and improves image quality when decentered.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an aspherical surface profile is used to counter positive spherical aberration of the cornea, then spherical aberration is reduced, but the lens becomes more sensitive to tilt and decentration, resulting in increased coma aberrations
Solution Approach 1:
The lens surface is segmented into multiple zones with different aspheric coefficients. The central zone has one set of aspheric coefficients optimized for spherical aberration correction, while the peripheral zone has different coefficients that reduce sensitivity to tilt and decentration. This segmentation allows each zone to independently optimize its function, resolving the contradiction between spherical aberration correction and coma aberration sensitivity.
Solution Approach 2:
Different regions of the lens surface are assigned different optical properties through varying aspheric coefficients. The central region maintains strong asphericity for spherical aberration correction, while the peripheral region adjusts its asphericity to minimize coma effects under misalignment conditions. This local differentiation of optical quality enables simultaneous optimization of both aberration types.
2Adaptability or versatility
If the lens is decentered with respect to the optical axis, then implantation flexibility is improved, but image quality deteriorates due to increased coma aberrations
Solution Approach 1:
The patent converts the harmful effect of decentration into a beneficial outcome by designing the peripheral zone with specific aspheric coefficients that actually reduce coma aberrations when the lens is decentered. What would normally be a defect (decentration sensitivity) is transformed into a feature where the lens performs better even when misaligned, allowing greater implantation flexibility without sacrificing image quality.
Solution Approach 2:
The aspheric coefficients in the peripheral zone are specifically optimized to change the optical behavior of the lens under decentration conditions. By adjusting these parameters, the lens maintains diffraction-limited image quality across a range of decentration values, enabling flexible implantation while preserving visual performance.
3Adaptability or versatility
If the lens is tilted with respect to the optical axis, then accommodation for different viewing angles is improved, but coma aberrations increase and image quality is reduced
Solution Approach 1:
The lens surface is divided into zones with differentiated aspheric properties, where the peripheral zone specifically addresses tilt-induced coma. This segmentation allows the central zone to maintain optimal optical performance for on-axis vision while the peripheral zone compensates for off-axis tilt, enabling multi-angle viewing without significant image quality degradation.
Data Source
AI summary
The present disclosure provides an ophthalmic lens that is disposed to balance coma aberrations if the lens, when inserted in a patient's eye, is decentered or tilted with respect to an optical axis of the patient's eye, and maintain a substantially diffraction-limited image quality if the lens, when inserted in the patient's eye, is centered with respect to the optical axis of the patient's eye. The lens may include an optic having an anterior surface and an opposing posterior surface disposed about an optical axis of the lens. One of the surfaces (e.g., the anterior surface) may have a semi-aspheric surface profile, which includes an inner region having a substantially spherical surface profile and extending radially from the optical axis of the lens to a first boundary, and an outer region having an aspherical surface profile and extending radially at least beyond the first boundary to a second boundary.