Intraocular Lens Power Calculation Using Iris Root OCT

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Solution Overview

Problem

Current methods for predicting the post-operative effective lens position (ELP) of intraocular lenses (IOLs) are inadequate, as they rely on pre-operative parameters that do not accurately reflect the final IOL position, leading to potential inaccuracies in IOL power calculation.

Innovation Solution

The use of optical coherence tomography (OCT) to measure the axial separation between the cornea and the iris root (ACD') and other parameters to improve ELP prediction, which is then integrated into IOL calculation formulas with empirically determined constants.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pre-operative parameters (ACD, AL) are used to predict post-operative ELP, then the measurement can be performed before surgery, but the prediction accuracy is insufficient

Engineering Contradiction:

ImproveELP prediction accuracyVSAvoidIOL power calculation accuracy

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by measuring the axial length of the iris root anteriorly (IRAA) before surgery using OCT imaging. This pre-operative measurement of the iris root position serves as a predictor for the post-operative ELP, allowing the surgical planning to be optimized based on the anticipated IOL position rather than relying on inaccurate pre-operative estimates.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If complex regression formulas are used to predict ELP, then more parameters can be incorporated, but the device complexity and calculation difficulty increase

Engineering Contradiction:

ImproveELP prediction accuracyVSAvoidcalculation formula complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the critical predictive information from complex multi-parameter regression formulas and isolates it into a single key measurement: the axial length of the iris root anteriorly (IRAA). By focusing on this one critical parameter measured via OCT, the system achieves accurate ELP prediction without requiring complex calculation formulas, thereby reducing device and calculation complexity while maintaining precision.

Inventive Principle:

Principle #2Taking out (Extraction)

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 approach provides a more accurate prediction of the IOL position, enhancing the precision of IOL power calculation and reducing the need for complex regression formulas, thereby improving surgical outcomes.

Implementation Method 1

an OCT device is used to identify the iris root. The axial separation (ACD') between the front surface of the cornea and the plane of the iris root is then determined.

Methodology Applied

Scientific EffectOptical coherence tomography:

Data Source

PatentUS9462938B2Method for determining the power of an intraocular lens

Publication Date: 2016.10.11 CARL ZEISS MEDITEC AG

AI summary

For the pre-operative calculation of the power of an intraocular lens, three input parameters are needed: the axial length of the eye (AL), the refractive power of the cornea, and the distance between the front of the cornea and the back focal plane of the intraocular lens, the so-called effective lens position (ELP). The invention shows a novel approach to the determination of the ELP.