Telecentric Keratometer and Swept-Source OCT for Whole-Eye Biometrics

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Solution Overview

Problem

Current devices for determining biometric variables of the eye, such as those used in intraocular lens calculations, face limitations in measuring all necessary parameters accurately and reliably, particularly due to movement artifacts, insufficient resolution, and the inability to correctly account for Skrew rays, leading to unreliable measurement values for whole-eye biometrics.

Innovation Solution

A device combining a multi-point keratometer with a laterally scanning swept-source OCT system, where the keratometer measurement points are illuminated and detected telecentrically, and the OCT system captures the whole eye over its axial length, allowing for accurate and reproducible measurement of corneal and retinal structures, thereby enabling reliable whole-eye biometrics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional topometers (Placido systems) are used to measure corneal topography, then high resolution is achieved, but measurement reliability deteriorates due to movement artifacts and positioning errors

Engineering Contradiction:

Improvecorneal topography resolutionVSAvoidmeasurement reproducibility

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the mechanical Placido topography system with an optical coherence tomography (OCT) based measurement system. This substitution eliminates the mechanical positioning and illumination issues that cause movement artifacts, providing both high resolution and reliable reproducible measurements of corneal topography and other ocular biometric parameters simultaneously

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If OCT systems are used to measure whole eye biometrics, then complete ocular parameters are obtained, but measurement reliability deteriorates due to movement artifacts and insufficient resolution

Engineering Contradiction:

Improvewhole eye measurement capabilityVSAvoidmeasurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent merges multiple measurement modalities into a single integrated system: OCT for cross-sectional imaging and biometric parameters, keratometry for corneal curvature, and topography for surface mapping. This combination allows simultaneous acquisition of complete ocular parameters with high reliability by cross-validating measurements and eliminating artifacts through multi-modal data fusion

Inventive Principle:

Principle #5Merging (Combining)

3Productivity

If faster OCT measurements are performed to reduce movement artifacts, then measurement speed is improved, but measurement precision deteriorates due to reduced sampling

Engineering Contradiction:

Improvemeasurement speedVSAvoidbiometric variable accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary eye tracking and fixation guidance before the actual measurement sequence begins. This preliminary positioning ensures the eye is properly aligned and stationary, allowing faster subsequent measurements without sacrificing precision. The system also performs preliminary calibration to optimize measurement parameters for the specific patient's eye characteristics

Inventive Principle:

Principle #10Preliminary action

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

This combination ensures accurate and reproducible measurement of biometric variables relevant for intraocular lens calculations, improving the reliability and speed of data acquisition by effectively accounting for Skrew rays and reducing movement artifacts, resulting in a more precise whole-eye model.

Implementation Method 1

the keratometer measurement points are illuminated and detected telecentrically

Methodology Applied

Scientific EffectTelecentric illumination and detection: Reflection

Implementation Method 2

OCT (optical coherence tomography) systems

Methodology Applied

Scientific EffectOptical coherence tomography: Interference

Implementation Method 3

the OCT arrangement is designed as a laterally scanning swept-source system with a detection region detecting the whole eye over the whole axial length

Methodology Applied

Scientific EffectLight scattering and reflection: Scattering

Data Source

PatentUS11950846B2Device for reliably determining biometric measurement variables of the whole eye

Publication Date: 2024.04.09 CARL ZEISS MEDITEC AG

AI summary

A device for determining biometric variables of the eye, as are incorporated in the calculation of intraocular lenses including a multi-point keratometer and an OCT arrangement. The keratometer measurement points are illuminated telecentrically and detected telecentrically and the OCT arrangement is designed as a laterally scanning swept-source system with a detection region detecting the whole eye over the whole axial length thereof. Illumination points are arranged in three rings concentrically around an instrument axis; and the three rings include a first ring, a second ring and a third ring and the illumination points on the first ring and the third ring are rotated in relation to the illumination points on the second ring such that each of the illumination points on the first ring is on a common radial with one of the illumination points on the third ring and each of the illumination points on the second ring is not on the common radial.