Excimer laser cutting parameter optimization method for presbyopia correction

Abstract

The invention relates to the technical field of ophthalmology medical treatment, in particular to an excimer laser cutting parameter optimization method for presbyopia correction, which comprises the following steps: (1) collecting eye data of a patient: collecting eye structure data and vision information of the patient; (2) establishing a personalized eye model: constructing a personalized eye three-dimensional model of the patient based on the collected eye data; (3) determining an optimization objective function: comprehensively considering the correction effects of far vision, near vision and middle vision and the risk of postoperative complications, and determining the optimization objective function; and (4) constructing a cutting parameter constraint condition: setting the cutting parameter constraint condition according to the eye condition of the patient. The method aims at solving the problems that in the prior art, an excimer laser cutting parameter optimization method for presbyopia correction is insufficient in the aspects of individuation, accuracy, comprehensiveness, safety and the like.

Description

Technical Field

[0001] This invention belongs to the field of ophthalmic medical technology, specifically a method for optimizing excimer laser ablation parameters for presbyopia correction. Background Technology

[0002] Presbyopia is an age-related physiological decline in visual accommodation, primarily manifested as difficulty seeing objects at close range. It typically begins between 40 and 45 years of age and gradually worsens with age. With the increasing aging population, the number of presbyopia patients is constantly rising, and the demand for presbyopia correction technology is becoming increasingly urgent. Excimer laser surgery, due to its advantages of minimal invasiveness and rapid recovery, has become one of the important clinical methods for correcting presbyopia. This surgery uses an excimer laser to precisely ablate corneal tissue, changing the refractive power of the cornea to correct vision. In excimer laser presbyopia correction surgery, the setting of ablation parameters is a key factor determining the surgical outcome, directly affecting the patient's postoperative distance vision, near vision, intermediate vision, and the risk of postoperative complications. However, existing methods for optimizing excimer laser cutting parameters have many defects and shortcomings: In terms of utilizing patient eye data, traditional methods often only collect a small amount of basic data such as corneal curvature and central corneal thickness. They lack comprehensive collection and effective utilization of key data such as corneal thickness distribution, anterior chamber depth, lens thickness, and pupil size changes under different lighting conditions. This makes it impossible to accurately grasp the differences in individual patient eye structures, resulting in a lack of targeted setting of ablation parameters and difficulty in meeting the personalized needs of different patients. In constructing eye models, existing technologies mostly use general eye models or simple two-dimensional models, failing to build personalized three-dimensional models based on the patient's specific eye data. General models cannot reflect the unique structural features of the patient's eye, and simple two-dimensional models are difficult to accurately describe the spatial relationships and morphology of various structures in the eye, thus affecting the accuracy and reliability of cutting parameter optimization. The setting of the optimization objective function is limited. Traditional methods usually only use the correction effect of distance or near vision as the main optimization target, ignoring the importance of intermediate vision and failing to fully consider the risk of postoperative complications. In addition, existing methods lack effective verification and adjustment of the optimized cutting parameters, often directly applying the optimized parameters to the surgery, making it impossible to predict the surgical effect and potential risks in advance. Once problems occur, they will have irreversible effects on the patient's vision. In summary, existing methods for optimizing excimer laser ablation parameters for presbyopia correction have shortcomings in terms of personalization, accuracy, comprehensiveness, and safety. There is an urgent need for an optimization method that can overcome these deficiencies to improve the effectiveness and safety of presbyopia correction surgery. Summary of the Invention

[0003] This invention relates to the field of ophthalmic medical technology, specifically to a method for optimizing excimer laser ablation parameters for presbyopia correction. This method addresses the shortcomings of existing excimer laser ablation parameter optimization methods for presbyopia correction in terms of personalization, accuracy, comprehensiveness, and safety.

[0004] This invention proposes a method for optimizing excimer laser ablation parameters for presbyopia correction, comprising the following steps: (1) Patient eye data acquisition: acquiring the patient's eye structure data and visual acuity information; (2) Establish a personalized eye model: Based on the collected eye data, construct a personalized three-dimensional eye model for the patient; (3) Determine the optimization objective function: Taking into account the corrective effects of distance vision, near vision, intermediate vision and the risk of postoperative complications, determine the optimization objective function; (4) Constructing cutting parameter constraints: Based on the patient's eye condition, set the cutting parameter constraints; (5) Using an improved intelligent optimization algorithm to optimize the parameters: Use an improved particle swarm optimization algorithm to optimize and solve the cutting parameters; (6) Verification and adjustment of cutting parameters: The optimized cutting parameters are verified and adjusted by simulation.

[0005] Furthermore, the eye structure data collected in step (1) includes corneal thickness distribution, corneal curvature, anterior chamber depth, lens thickness, and pupil size changes under different lighting conditions. The visual acuity information includes distance vision, near vision, intermediate vision, and astigmatism.

[0006] Furthermore, in step (2), when establishing a personalized eye model, three-dimensional modeling technology is used to first construct a three-dimensional model of the cornea based on the corneal thickness distribution and corneal curvature data, then construct a three-dimensional model of the anterior chamber and lens based on the anterior chamber depth and lens thickness data, and finally combine the various models to form a complete personalized three-dimensional eye model.

[0007] Further, the expression for the objective function optimized in step (3) is F (x) = w1×f1 (x) + w2×f2(x) + w3×f3 (x) + w4×f4 (x), where x is the cutting parameter vector, including cutting depth, cutting diameter, and cutting center position; f1 (x) is the distance vision correction effect function; f2 (x) is the near vision correction effect function; f3 (x) is the intermediate vision correction effect function; f4 (x) is the postoperative complication risk function; w1, w2, w3, and w4 are the weight coefficients of each objective function, and the weight coefficients are adjusted according to the patient's specific needs and eye conditions.

[0008] Furthermore, the cutting parameter constraints in step (4) include that the remaining thickness after corneal cutting is not less than the safety value, the cutting range does not exceed the safe area of ​​the cornea, and the deviation between the cutting center position and the pupil center is within the preset range.

[0009] Furthermore, the improved particle swarm optimization algorithm in step (5) introduces adaptive inertia weight and crossover / mutation operations. The initial value of the adaptive inertia weight is 0.9, which decreases linearly to 0.4 as the number of iterations increases. The crossover probability is 0.5, the mutation probability is 0.1, the particle swarm size is 50, and the maximum number of iterations is 100.

[0010] Furthermore, the improved particle swarm optimization algorithm in step (5) introduces adaptive inertia weight and crossover / mutation operations. The initial value of the adaptive inertia weight is 0.9, which decreases linearly to 0.4 as the number of iterations increases. The crossover probability is 0.5, the mutation probability is 0.1, the particle swarm size is 50, and the maximum number of iterations is 100.

[0011] Furthermore, the preset requirements are that distance vision reaches 1.0 or above, near vision reaches 0.8 or above, intermediate vision reaches 0.8 or above, and the maximum corneal stress is less than the safety threshold.

[0012] Furthermore, the ocular imaging equipment used in step (1) includes an optical coherence tomography scanner, a corneal topography instrument, an anterior chamber depth meter, and a pupil meter, and visual information is obtained using a standard visual acuity chart and an optometry instrument.

[0013] Furthermore, the postoperative complication risk function f4(x) is positively correlated with the corneal ablation depth and ablation range, that is, the greater the corneal ablation depth and the wider the ablation range, the higher the risk of postoperative complications.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention achieves truly personalized ablation parameter optimization: By comprehensively collecting the patient's ocular structural data, including corneal thickness distribution, corneal curvature, anterior chamber depth, lens thickness, and pupil size variations under different lighting conditions, as well as detailed visual acuity information such as distance vision, near vision, intermediate vision, and astigmatism, a personalized three-dimensional ocular model is constructed based on this data. This allows the optimization of ablation parameters to fully consider the individual differences in the patient's ocular structure, overcoming the limitations of traditional methods that rely on general models or simple data. It tailors the optimal ablation plan for each patient, greatly improving the targetedness and effectiveness of the surgery. 2. Significant Multi-Objective Optimization Results, Balancing Visual Needs at Different Distances: The optimization objective function of this invention comprehensively considers the corrective effects of distance vision, near vision, and intermediate vision, as well as the risk of postoperative complications. By setting reasonable weighting coefficients, it can balance different visual goals according to the patient's specific needs (such as occupation, lifestyle, etc.). For example, for patients who frequently need to alternate between near and far vision, the weight of intermediate vision can be appropriately increased; for patients who mainly work at close range, the weight of near vision can be increased. This multi-objective optimization approach solves the problem of traditional methods focusing only on a single visual goal, ensuring that patients can obtain good vision at different distances (far, intermediate, and near) after surgery, significantly improving their quality of life. 3. Improved surgical safety and reduced postoperative complication risk: This invention fully considers the biomechanical stability of the cornea when constructing the ablation parameter constraints, setting constraints such as the remaining corneal thickness after ablation not being less than a safe value and the ablation range not exceeding the safe corneal region. Simultaneously, a postoperative complication risk function is incorporated into the optimization objective function, and the optimization algorithm controls parameters such as corneal ablation depth and ablation range, achieving an optimal balance between postoperative complication risk and visual correction effect. Furthermore, simulation verification of the optimized ablation parameters allows for early assessment of corneal biomechanical performance, further reducing the probability of postoperative complications such as corneal ectasia, glare, and dry eye. 4. Optimized Algorithm for High Efficiency and Precision, Improving Parameter Optimization Efficiency and Quality: This invention employs an improved particle swarm optimization algorithm, introducing adaptive inertia weights and crossover / mutation operations. Adaptive inertia weights dynamically adjust the particle search capability according to the iteration process, maintaining a larger inertia weight in the early stages to enhance global search capability, and decreasing the inertia weight in the later stages to improve local optimization accuracy. Crossover / mutation operations increase particle diversity, preventing the algorithm from getting trapped in local optima. Compared with traditional optimization algorithms, this improved algorithm converges faster and can find the globally optimal combination of cutting parameters in a shorter time. For example, in the embodiment, satisfactory results were obtained in only 100 iterations, greatly improving the efficiency and quality of parameter optimization and providing strong support for the smooth operation. 5. A robust verification and adjustment mechanism ensures the reliability of cutting parameters: This invention incorporates a verification and adjustment process for cutting parameters. The optimized cutting parameters are applied to a personalized eye model for simulated cutting, and optical simulation software is used to calculate postoperative visual acuity and corneal biomechanical properties. If the simulation results do not meet the preset requirements (e.g., distance visual acuity of 1.0 or higher, near and intermediate visual acuity of 0.8 or higher, maximum corneal stress less than the safety threshold), the weighting coefficients or constraints of the objective function are adjusted promptly, and parameter optimization is repeated until satisfactory results are obtained. This closed-loop verification and adjustment mechanism effectively avoids surgical risks caused by improper parameter settings, ensuring that the final determined cutting parameters have extremely high reliability and effectiveness, providing a solid guarantee for surgical success. 6. Comprehensive data acquisition and advanced equipment provide a solid foundation for optimization: This invention employs advanced ocular imaging equipment such as an optical coherence tomography scanner, corneal topography instrument, anterior chamber depth meter, and pupil meter, enabling comprehensive and accurate acquisition of the patient's ocular structural data. Simultaneously, it combines standard visual acuity charts and optometry to obtain detailed visual acuity information. This high-quality, multi-dimensional data provides a solid foundation for the construction of personalized ocular models, the determination of optimization objective functions, and the optimization of ablation parameters, ensuring the scientific rigor and accuracy of the entire optimization process. Attached Figure Description

[0015] Figure 1 This is a flowchart of a method for optimizing excimer laser ablation parameters for presbyopia correction according to the present invention. Figure 2 This is a schematic diagram of a personalized three-dimensional eye model for an excimer laser ablation parameter optimization method for presbyopia correction according to the present invention.

[0016] Figure 3 This is a flowchart of the particle swarm optimization algorithm for an excimer laser ablation parameter optimization method for presbyopia correction according to the present invention.

[0017] Figure 4 This is a comparison of visual acuity before and after laser ablation, based on the method for optimizing excimer laser ablation parameters for presbyopia correction according to the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0019] This invention provides a method for optimizing excimer laser ablation parameters for presbyopia correction. Example 1: Basic Implementation Example: A method for optimizing excimer laser ablation parameters for presbyopia correction. This embodiment uses a 60-year-old presbyopic patient as an example to explain in detail the implementation process of the optimization method.

[0020] (1) Patient eye data collection Equipment: Optical coherence tomography (OCT) was used to obtain corneal thickness distribution, corneal topography was used to measure corneal curvature, an anterior chamber depth meter was used to collect anterior chamber depth, and a pupil meter was used to record pupil size changes under dim light, normal light, and strong light.

[0021] Visual acuity information: Distance visual acuity (0.6), near visual acuity (0.4), intermediate visual acuity (0.5), and astigmatism (-1.0D) are obtained using a standard visual acuity chart and an optometry instrument.

[0022] (2) Establish a personalized three-dimensional model of the eye Based on corneal thickness distribution and curvature data, an asymmetric corneal model is constructed using 3D modeling software (such as ANSYS). By integrating data on anterior chamber depth (3.2 mm) and lens thickness (4.0 mm), an anterior chamber and lens model were constructed. The sub-models are combined into a complete 3D model of the eye, and the optical zone and peripheral zone are labeled.

[0023] (3) Determine the optimization objective function The objective function is defined as: F(x)=w1⋅f1(x)+w2⋅f2(x)+w3⋅f3(x)+w4⋅f4(x) Parameters: x = [depth of cut (μm), diameter of cut (mm), coordinates of the cutting center (mm)]; Function definition: f1(x): Correction effect for distance vision (target value ≥ 1.0) f2(x): Near vision correction effect (target value ≥ 0.8) f3(x): Intermediate visual acuity correction effect (target value ≥ 0.8) f4(x) = k1⋅Depth of cut + k2⋅Depth of cut f4 (x) = k1 ⋅ depth of cut + k2 ⋅ cutting area Weights: Adjusted according to patient needs (w1=0.3, w2=0.4, w3=0.2, w4=0.1) It focuses on improving near vision.

[0024] (4) Cutting parameter constraints Remaining corneal thickness ≥ safe value (250μm); Cutting diameter ≤ Corneal optical zone diameter (6.0mm); The deviation between the cutting center and the pupil center is ≤ 0.2mm.

[0025] (5) Improved Particle Swarm Optimization Algorithm for Solving Algorithm parameters: Particle swarm size: 50, maximum number of iterations: 100; Adaptive inertia weight: 0.9 → 0.4 (linearly decreasing); Crossover probability: 0.5, mutation probability: 0.1.

[0026] Optimization process: Initialize the particle swarm (randomly generate a combination of cutting parameters); Calculate the fitness value F(x) for each particle; Update particle positions (introduce crossover mutation to avoid local optima); Iterate until the termination condition is met (100 generations or visual acuity meets the standard: far ≥1.0, near ≥0.8, intermediate ≥0.8, and corneal stress < safety threshold).

[0027] (6) Verification and adjustment of cutting parameters Simulation verification: The optimized parameters were input into the eye model to predict postoperative visual acuity (far 1.2 / near 0.9 / intermediate 0.85) and corneal stress distribution; Parameter adjustment: Since the cutting center deviation of 0.15mm was close to the critical value, the center coordinates were finely adjusted to a deviation of 0.1mm and then verified.

[0028] Example Effects Final optimized parameters: cutting depth = 110 μm, diameter = 5.5 mm, center coordinates (0.05, -0.03) mm. Postoperative simulation showed: Vision meets the standard (far 1.2 / near 0.9 / intermediate 0.85); The remaining corneal thickness is 260μm (>safe value), and the maximum stress is below the threshold, meeting the preset requirements.

[0029] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0030] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0031] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for optimizing excimer laser ablation parameters for presbyopia correction, characterized in that, Includes the following steps: (1) Patient eye data collection: Collect patient eye structure data and visual acuity information; (2) Establish a personalized eye model: Based on the collected eye data, construct a personalized three-dimensional eye model for the patient; (3) Determine the optimization objective function: Taking into account the corrective effects of distance vision, near vision, intermediate vision and the risk of postoperative complications, determine the optimization objective function; (4) Constructing cutting parameter constraints: Based on the patient's eye condition, set the cutting parameter constraints; (5) Using an improved intelligent optimization algorithm to optimize the parameters: Use an improved particle swarm optimization algorithm to optimize and solve the cutting parameters; (6) Verification and adjustment of cutting parameters: The optimized cutting parameters are verified and adjusted by simulation.

2. The method for optimizing excimer laser ablation parameters for presbyopia correction according to claim 1, characterized in that, The eye structure data collected in step (1) includes corneal thickness distribution, corneal curvature, anterior chamber depth, lens thickness, and pupil size changes under different lighting conditions. The visual acuity information includes distance vision, near vision, intermediate vision, and astigmatism.

3. The method for optimizing excimer laser ablation parameters for presbyopia correction according to claim 1, characterized in that, In step (2), when establishing a personalized eye model, three-dimensional modeling technology is used to first construct a three-dimensional model of the cornea based on the corneal thickness distribution and corneal curvature data, then construct a three-dimensional model of the anterior chamber and lens based on the anterior chamber depth and lens thickness data, and finally combine the various models to form a complete personalized three-dimensional eye model.

4. The method for optimizing excimer laser ablation parameters for presbyopia correction according to claim 1, characterized in that, In step (3), the expression for the objective function is F(x) = w1×f1(x) + w2×f2(x) + w3×f3(x) + w4×f4(x), where x is the cutting parameter vector, including cutting depth, cutting diameter, and cutting center position; f1(x) is the distance vision correction effect function; f2(x) is the near vision correction effect function; f3(x) is the intermediate vision correction effect function; f4(x) is the postoperative complication risk function; w1, w2, w3, and w4 are the weight coefficients of each objective function, and the weight coefficients are adjusted according to the patient's specific needs and eye conditions.

5. The method for optimizing excimer laser ablation parameters for presbyopia correction according to claim 1, characterized in that, The cutting parameter constraints in step (4) include that the remaining thickness of the cornea after cutting is not less than the safe value, the cutting range does not exceed the safe area of ​​the cornea, and the deviation between the cutting center position and the pupil center is within the preset range.

6. The method for optimizing excimer laser ablation parameters for presbyopia correction according to claim 1, characterized in that, The improved particle swarm optimization algorithm in step (5) introduces adaptive inertia weight and crossover and mutation operations. The initial value of the adaptive inertia weight is 0.9, which decreases linearly to 0.4 as the number of iterations increases. The crossover probability is 0.5, the mutation probability is 0.1, the particle swarm size is 50, and the maximum number of iterations is 100.

7. The method for optimizing excimer laser ablation parameters for presbyopia correction according to claim 1, characterized in that, The improved particle swarm optimization algorithm in step (5) introduces adaptive inertia weight and crossover and mutation operations. The initial value of the adaptive inertia weight is 0.9, which decreases linearly to 0.4 as the number of iterations increases. The crossover probability is 0.5, the mutation probability is 0.1, the particle swarm size is 50, and the maximum number of iterations is 100.

8. The method for optimizing excimer laser ablation parameters for presbyopia correction according to claim 7, characterized in that, The preset requirements are: distance visual acuity of 1.0 or above, near visual acuity of 0.8 or above, intermediate visual acuity of 0.8 or above, and maximum corneal stress less than the safety threshold.

9. The method for optimizing excimer laser ablation parameters for presbyopia correction according to claim 1, characterized in that, The ocular imaging equipment used in step (1) includes an optical coherence tomography scanner, a corneal topography instrument, an anterior chamber depth meter, and a pupil meter. Visual acuity information is obtained using a standard visual acuity chart and an optometry instrument.

10. The method for optimizing excimer laser ablation parameters for presbyopia correction according to claim 4, characterized in that, The postoperative complication risk function f4(x) is positively correlated with the corneal ablation depth and ablation range, that is, the greater the corneal ablation depth and the wider the ablation range, the higher the risk of postoperative complications.

Images