Corneal Volume Calculation for Refractive Surgery
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Solution Overview
Problem
Conventional LASIK methods for surgical correction of ametropia lack precision in defining the cut surface required to isolate a volume of corneal tissue for effective refractive surgery, relying on heuristic approaches that are not analytically precise.
Innovation Solution
A treatment device and method that utilize focused laser radiation to create a precise three-dimensional cut surface in the cornea, with control data specifying target points to isolate a volume whose removal corrects ametropia, based on an analytical equation defining the radius of curvature of the cornea post-correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional LASIK methods use heuristic approaches to determine volume removal, then the surgical process is simpler to implement, but the precision of defining the cut surface is insufficient
Solution Approach 1:
The patent applies preliminary action by pre-calculating the exact volume to be removed and defining the precise cut surface geometry before surgery. The analytical equations determine the anterior and posterior partial surfaces in advance, allowing the surgical device to follow predetermined paths with high precision, thereby resolving the contradiction between precision and complexity.
Solution Approach 2:
The patent segments the cut surface into distinct anterior and posterior partial surfaces, each defined by specific analytical equations. This segmentation allows independent optimization of each surface's geometry and facilitates precise control of the surgical device, enabling high manufacturing precision without excessive overall complexity.
2Measurement precision
If heuristic methods are used to determine volume removal, then the surgical procedure is easier to perform, but the optical correction accuracy is reduced
Solution Approach 1:
The patent replaces heuristic and empirical methods with analytical equations that precisely calculate the required volume removal based on optical parameters. This substitution of mechanical/empirical approaches with mathematical models ensures accurate optical correction while the automated computational system maintains ease of operation.
Solution Approach 2:
The analytical equations in the patent enable the system to self-determine the precise cut surface geometry and volume to be removed based on measured corneal parameters. This self-service capability eliminates the need for complex manual calculations during surgery, maintaining ease of operation while achieving high measurement precision.
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
Enables precise calculation and implementation of the volume to be removed, ensuring accurate optical correction by analytically determining the anterior and posterior partial surfaces of the cornea, thereby improving the precision and effectiveness of refractive surgery.
Implementation Method 1
If the power density of the radiation during a pulse is above a threshold value, an optical breakthrough occurs, which creates a plasma bubble in the cornea
Implementation Method 2
The pulsed laser radiation is used for tissue separation, with the pulse length usually being less than 1 ps
Implementation Method 3
an optical breakthrough occurs, which creates a plasma bubble in the cornea
Data Source
Figure 1~6
Figure 1a
Figure 3~7
AI summary
A device is described for corrective surgery of defective vision of an eye (3) of a patient (4). The device comprises a laser apparatus (L) that is controlled by a controller (12) and cuts corneal tissue by means of a laser beam (2). In order to focus the laser beam (2) in the cornea (5), the controller (12) steers the laser apparatus (L) towards a target point (28) located in a pattern in the cornea (5), and selects the pattern in such a way that it lies at the boundary of a volume (18) in the cornea (5) which, when removed from the cornea (18), produces the desired correction of defective vision. The controller selects the pattern in such a way that the boundary circumscribes a volume formed such that the cornea (5) less the volume (18) has a radius of curvature RCV* which satisfies the following equation: RCV*=1/((1/RCV)+BBR/((nc-1)(1-dHS⋅BBR)))+F, in which RCV is the radius of curvature of the cornea (5) before the volume (18) is removed, nc is the refractive power of the cornea (5) tissue, F is a factor, BBR is the refractive power of spectacles (17) capable of correcting defective vision, and dHS is the distance from the corneal apex at which the spectacles (17) having the refractive power BBR would have to be located for the spectacles (17) to achieve the desired correction of defective vision.