IOL Peripheral Posterior Surface Design for Negative Dysphotopsia
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Solution Overview
Problem
Intraocular lenses (IOLs) often cause aberrant optical phenomena such as halos, glare, or dark regions in the visual field, particularly shadows in the peripheral vision, known as negative dysphotopsia, due to the double imaging effect when light enters the eye at large angles, which conventional designs fail to adequately address.
Innovation Solution
The IOLs feature a peripheral region on their posterior surface designed to redirect light rays incident at large angles, via refraction by the anterior surface, to a reduced intensity region between the primary and secondary peripheral images, thereby alleviating and preventing the perception of shadows by directing light to offset retinal locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the IOL optic diameter is reduced to facilitate easier surgical insertion and smaller corneal incision, then ease of surgery and reduction of corneal aberrations are improved, but the ability to receive all light entering the eye deteriorates, causing peripheral light to miss the IOL and form a second peripheral image that results in negative dysphotopsia
Solution Approach 1:
The IOL optic is designed with different optical properties in different regions: the central region has a first optical power for forming the primary retinal image, while the peripheral region has a second optical power that directs peripheral light rays to an intermediate image location rather than allowing them to form a separate secondary peripheral image. This local differentiation resolves the contradiction by maintaining the reduced optic diameter for easy insertion while preventing negative dysphotopsia through region-specific optical functionality.
2Length of stationary object
If the IOL optic diameter is reduced to facilitate easier surgical insertion and smaller corneal incision, then corneal incision size is reduced, but peripheral vision quality deteriorates due to the double imaging effect
Solution Approach 1:
The peripheral region of the IOL optic is designed with a specific optical power that differs from the central region. This peripheral region actively directs oblique peripheral light rays to an intermediate image location on the retina, ensuring that peripheral vision is formed by a single image rather than creating a separate secondary peripheral image. This maintains high peripheral vision quality despite the reduced optic diameter required for small corneal incision.
3Device complexity
If conventional IOL designs are used with reduced optic diameter, then surgical complexity is reduced, but visual artifacts such as halos, glare, and shadows in the peripheral visual field increase
Solution Approach 1:
The IOL optic incorporates region-specific optical powers: the central region provides standard focusing for the primary image, while the peripheral region provides a different optical power specifically optimized to direct peripheral light rays to an intermediate image location. This design maintains simple surgical procedures while eliminating visual artifacts such as halos, glare, and shadows that would otherwise result from the double imaging effect in reduced-diameter IOLs.
Solution Approach 2:
Instead of allowing peripheral light rays that miss the reduced-diameter optic to form harmful secondary peripheral images causing negative dysphotopsia, the invention captures these same peripheral rays through the peripheral region of the optic and redirects them to form a useful intermediate image on the retina. This converts the potentially harmful stray light into a beneficial optical function that improves peripheral vision while maintaining simple surgery.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design significantly reduces or eliminates the perception of peripheral visual artifacts, enhancing the quality of peripheral vision and reducing the occurrence of dysphotopsia, while maintaining on-axis image quality and allowing for easier surgical insertion and reduced corneal incision size.
Implementation Method 1
redirect light rays incident at large angles, via refraction by the anterior surface, to a reduced intensity region between the primary and secondary peripheral images
Data Source
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AI summary
An IOL (10) is disclosed that includes an anterior surface (14) and a posterior surface (16) disposed about an optical axis (OA), where the posterior surface includes a central region (20) extending to a peripheral region (22). Once the IOL is implanted in a patient's eye, the anterior surface and the central region of the posterior surface cooperatively form an image of a field of view on the retina and the peripheral region of the posterior surface directs at least some light rays 'incident thereon (e.g., via refraction by the anterior surface) to at least one retinal location offset from the image so as to inhibit dysphotopsia.