Intraocular Lens Power Calculation Using Anterior Chamber Depth
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Solution Overview
Problem
Current intraocular lens power calculation methods are prone to errors, particularly in estimating postoperative lens position, which contributes significantly to refractive outcomes in cataract surgery, and are inadequate for patients who have undergone corneal refractive surgery, as they rely on parameters that may no longer be applicable.
Innovation Solution
A method and system for accurately determining intraocular lens power by measuring axial length, anterior chamber depth prior to surgery, and corneal radius, using predictive formulations that calculate postoperative anterior chamber depth and lens haptic plane, reducing reliance on thin-lens theory and incorporating constants derived from regression analysis to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current intraocular lens power calculation formulas are used, then lens power can be determined using standard parameters, but significant errors occur in estimating postoperative lens position contributing to refractive outcomes
Solution Approach 1:
The patent changes the parameters used in lens power calculation by incorporating preoperative anterior chamber depth and using it to predict postoperative anterior chamber depth, rather than relying on traditional formulas that directly estimate postoperative lens position. This parameter transformation reduces estimation errors by focusing on a more stable preoperative measurement.
Solution Approach 2:
The patent introduces preoperative anterior chamber depth as an intermediary parameter that mediates between preoperative measurements and postoperative lens position. Instead of directly estimating the difficult-to-measure postoperative lens position, the method uses the intermediary of anterior chamber depth prediction to achieve more accurate results.
2Adaptability or versatility
If traditional power calculation formulas relying on corneal radius or power are used, then calculations can be performed for normal eyes, but erroneous estimates occur for patients who have undergone corneal refractive surgery
Solution Approach 1:
The patent extracts the problematic dependency on corneal radius or power from the calculation formula. By removing the direct reliance on these parameters that are altered by corneal refractive surgery, the method avoids the erroneous estimates that occur when applying traditional formulas to post-refractive surgery patients.
Solution Approach 2:
The patent creates a universal calculation method that works for both normal eyes and eyes with prior corneal refractive surgery. By using preoperative anterior chamber depth and axial length as basis for prediction, the formula becomes multi-functional and applicable to diverse patient populations without requiring separate correction factors.
3Measurement precision
If multiple ocular parameters including lens thickness are measured to improve calculation accuracy, then more data is available for power determination, but the complexity of measurements and procedures increases
Solution Approach 1:
The patent extracts and eliminates the requirement for lens thickness measurement from the traditional calculation protocol. By demonstrating that preoperative anterior chamber depth and axial length are sufficient for accurate prediction, the method removes the need for additional complex measurements while maintaining or improving accuracy.
Data Source
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AI summary
A system for providing an intraocular lens includes a processor and a computer readable memory. The computer readable memory is configured to communicate with the processor, the memory having stored therein at least one of: one or more ocular dimensions, and at least one predetermined refractive outcome. The memory further includes a sequence of instructions which, when executed by the processor, cause the processor to select an intraocular lens, select a power of an intraocular lens, or provide an intraocular lens. The sequence of instructions includes determining one or more dimensions of an eye. The instructions also include calculating, based on a mathematical relationship, a distance from an apex of a cornea of the eye to an apex or plane of the intraocular lens after insertion into the eye. The instructions further calculating an optical power of the intraocular lens suitable for providing a predetermined refractive outcome. The mathematical relationship includes an axial length of the eye, an anterior chamber depth of the natural crystalline lens, and a corneal radius of the eye, but is independent of a thickness of the natural crystalline lens.