Structured Incision Geometry for Uniform Astigmatic Correction
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Solution Overview
Problem
Existing ophthalmic surgical procedures for astigmatic keratotomy and limbal relaxing incisions result in non-uniform corrective effects due to uniform incision depth and angle of attack, leading to uneven tissue relaxation and increased risk of errors and complications.
Innovation Solution
A system and method for creating structured incisions with varying depth, width, and angle of attack along the length of the incision, using both manual and automated laser surgery systems to ensure a more consistent corrective effect by inducing a greater relaxing effect towards the incision's end portions, thereby counteracting the natural central relaxing effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If uniform incision depth and angle of attack are used, then the surgical procedure is simple and quick, but the corrective effect is non-uniform and inconsistent
Solution Approach 1:
The patent applies local quality by varying the incision depth and angle of attack at different locations along the incision arc. Specifically, the incision depth is increased at the end portions compared to the central portion, and the angle of attack is adjusted to be more perpendicular at the ends. This creates location-specific incision characteristics that compensate for the non-uniform relaxing effect, achieving uniform overall correction.
Solution Approach 2:
The patent changes the geometric parameters of the incision along its length. The depth parameter varies from shallower at the center to deeper at the ends, and the angle of attack parameter varies from more parallel to the surface at the center to more perpendicular at the ends. These parameter variations are designed to produce a uniform relaxing effect throughout the incision.
2Manufacturing precision
If supplemental incisions are made to correct non-uniform relaxing effect, then the corrective precision is improved, but the surgical time and complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-planning the non-uniform incision geometry before the surgical procedure. The incision parameters (depth and angle variations) are determined in advance based on the desired uniform corrective effect, eliminating the need for supplemental incisions and reducing surgical time.
Solution Approach 2:
The patent extracts the need for supplemental incisions by incorporating the corrective function directly into the primary incision geometry. By designing the main incision with varying depth and angle, the uniform relaxing effect is achieved without requiring additional corrective incisions, thus removing the time-consuming step.
3Manufacturing precision
If diamond blade is used for manual incision, then the cutting precision is good, but the incision depth is shallower at ends than center due to blade geometry
Solution Approach 1:
The patent applies inversion by reversing the conventional approach. Instead of accepting the natural shallow-deep-shallow profile created by the diamond blade and trying to correct it with supplemental incisions, the patent deliberately creates a deep-shallow-deep profile by controlling the blade penetration depth and angle. This inverted approach naturally achieves uniform relaxing effect without additional corrections.
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
The structured incision technique provides a more uniform and consistent corrective effect, reducing the need for supplemental incisions, minimizing trauma and risks, and improving the predictability of astigmatic correction while reducing higher-order aberrations.
Implementation Method 1
an automated laser surgery system to selectively ablate ophthalmic tissue to provide an elongated structured incision
Data Source
AI summary
A method and apparatus for making improved surgical incisions in corrective eye surgery are provided. It was observed that a uniform elongated AK (or LRI) incision provides a non-uniform corrective effect due to non-uniform post-surgical relaxation of ophthalmic tissue. The method and apparatus leverage this observation to provide for creation of a surgical incision that is structured to be non-uniform along its length in such a manner as to at least partially counteract an expected variation in ophthalmic tissue relaxation to provide overall increased uniformity of corrective effect. An automated laser surgery system includes a laser control system configured to control laser delivery to cause selective ablation of ophthalmic tissue to provide an elongated structured incision that varies along its length in at least one of a depth, a profile, a width, and an angle of attack relative to a surface of the ophthalmic tissue.