Eye Rotation Center Position Estimation Using Geometric Modeling
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Solution Overview
Problem
Current methods for determining the position of the eye rotation center (ERC) are either inaccurate due to approximations or time-consuming, making it challenging to quickly and precisely calculate personalized ophthalmic lenses.
Innovation Solution
A method using a simple geometric model of the eye, comprising two nested spheres for the sclera and cornea, to estimate the position of the ERC based on personal parameters such as the outer diameter of the iris, anterior chamber depth, and eye length, without the need for a reference accessory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a mean value for the radius of the eye is assumed to determine the ERC position from the cornea position, then the method is simple and quick to implement, but the measurement precision deteriorates significantly due to individual variations in eye radius
Solution Approach 1:
The patent changes the approach from using a fixed mean radius value to using an individualized eye radius value derived from optical coherence tomography (OCT) measurements. By measuring the actual axial length and corneal curvature of each subject's eye, the method adapts the radius parameter to individual anatomical variations, thereby improving measurement precision while maintaining practical implementation through automated OCT imaging.
2Measurement precision
If image processing methods with reference accessories are used to determine the ERC position, then the measurement precision improves, but the device complexity and time required increase significantly
Solution Approach 1:
The patent extracts and removes the complex reference accessory component from the measurement system. Instead of requiring external reference accessories and complex image processing setups, the method uses standard OCT imaging equipment to directly measure eye anatomical parameters (axial length, corneal curvature) that are then used to calculate the ERC position. This simplifies the device while maintaining precision through direct anatomical measurement rather than indirect image processing.
3Measurement precision
If image processing methods with reference accessories are used to determine the ERC position, then the measurement precision improves, but the time required to perform the measurement increases
Solution Approach 1:
The patent performs preliminary measurement of the eye's anatomical parameters (axial length, corneal curvature) using OCT imaging before the ERC position calculation is needed. These pre-measured anatomical data are then directly used in the ERC position determination, eliminating the need for time-consuming reference accessory calibration and multiple image captures. The preliminary anatomical characterization enables rapid, precise ERC positioning without repeated measurements.
Data Source
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AI summary
The invention relates to a method for determining the position (dERC) of the eye rotation center (2) of the eye (1) of a subject comprising: - providing a geometric model of an eye, whereby the position of the eye rotation center of this eye is determined based on a set of personal parameters (LE, dAC, DI, AGE, K) including at least a first geometric dimension (DI) of the eye, each personal parameter being distinct from said position of the eye rotation center; - determining a value of each personal parameter for the subject; and - determining a first approximate value of said position of the eye rotation center in accordance with said geometric model based on the values of the personal parameters. The invention concerns also a method for calculating a personalized ophthalmic lens for the eye of the subject based on this determination of the position of the eye rotation center. The invention finally relates to a device for determining a position of the eye rotation center of an eye of a subject using this method.