Cornea Shape Measurement Apparatus Astigmatic Axis Alignment
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Solution Overview
Problem
Current cornea shape measurement apparatuses fail to accurately determine the astigmatic axis of the eye, leading to potential misalignment during the injection of TORIC-IOLs due to variations in patient posture during measurement and marking.
Innovation Solution
A cornea shape measurement apparatus that includes a projecting optical system for indexing the cornea shape, an illuminating optical system using green light to enhance visibility of reference marks, an imaging system capturing anterior segment images, and a processor overlaying astigmatic axis marks on the images to determine the axis direction, allowing for precise alignment of the IOL.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a cornea shape measurement apparatus projects an index onto the cornea and captures the reflected image to measure cornea shape, then the cornea shape measurement is achieved, but the apparatus cannot provide accurate astigmatic axis data for TORIC-IOL injection alignment
Solution Approach 1:
The patent combines the cornea shape measurement function with the astigmatic axis determination function into a single integrated apparatus. The same imaging device captures both the reflected index image for cornea shape measurement and the reference mark image for astigmatic axis determination, merging two measurement functions into one system that provides comprehensive data for both prescription and injection alignment of TORIC-IOLs
Solution Approach 2:
The imaging device serves multiple functions: it captures the reflected index image for cornea shape measurement, captures the reference mark image for astigmatic axis determination, and provides visual guidance for injection alignment. This multi-functional design eliminates the need for separate measurement devices and ensures consistent coordinate system reference throughout the measurement and injection process
2Ease of operation
If the operator manually places marks on the patient's eye based on cornea shape measurement, then the TORIC-IOL injection can be performed, but posture variations cause misalignment and injection position deviation
Solution Approach 1:
The apparatus determines the astigmatic axis and generates visual guidance information before the injection procedure. By pre-calculating the astigmatic axis direction and displaying it as an overlay on the anterior segment image, the system prepares accurate alignment information in advance, eliminating the need for manual marking and reducing errors from posture variations during the procedure
Solution Approach 2:
The system provides visual feedback by overlaying the astigmatic axis mark and angle information on the displayed anterior segment image. This real-time visual guidance allows the operator to verify the calculated astigmatic axis and make adjustments if needed, ensuring accurate injection alignment while maintaining the simplicity of the operation
3Illumination intensity
If the apparatus uses visible light illumination and imaging to capture the anterior segment, then the reference mark visibility is improved, but the ink color of the reference mark must be considered to avoid interference
Solution Approach 1:
The patent specifies using green light (wavelength 500-600 nm) for illumination and imaging. This wavelength range is strategically chosen because it provides high contrast with common reference mark ink colors (blue and purple) while avoiding interference with the ink's light absorption characteristics. The green light illuminates the anterior segment and reflects off the reference mark, making it clearly visible in the captured image without being absorbed or distorted by the ink
Solution Approach 2:
The system adjusts the wavelength parameter of the illumination light to optimize visibility. By selecting green light with a center wavelength in the 500-600 nm range, the apparatus achieves optimal contrast for reference marks regardless of whether blue or purple ink is used. This parameter optimization ensures consistent reference mark visibility and accurate astigmatic axis determination across different marking conditions
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 apparatus provides accurate data for TORIC-IOL prescription and injection by ensuring precise alignment of the IOL with the astigmatic axis, reducing the risk of deviation and improving the accuracy of astigmatism correction.
Implementation Method 1
projects an index for cornea shape measurement onto a cornea of an examinee's eye
Implementation Method 2
illuminates an anterior segment of the eye, on which a reference mark for intraocular lens operations is placed, with visible light
Implementation Method 3
captures an anterior segment image containing the reference mark and an image of the index reflected from the cornea
Data Source
AI summary
A cornea shape measurement apparatus outputs data useful for prescription as well as injection and installation of a TORIC-IOL. This apparatus includes: a projecting optical system projecting an index for measurement onto a cornea; an illuminating optical system illuminating an anterior segment on which a reference mark is placed; an imaging optical system capturing an anterior segment image containing the reference mark and an image of the index reflected from the cornea; an image processor overlaying an astigmatic axis mark indicating a direction of an astigmatic axis of the cornea, which is calculated based on the index image, on the anterior segment image; and a controller displaying the anterior segment image, which contains the astigmatic axis mark, on a display.