Placido Ring Pattern for Easier Corneal Topography Analysis
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Solution Overview
Problem
Placido topographers face difficulties in analyzing reflected patterns due to their complexity, making it challenging to accurately determine corneal surface topography.
Innovation Solution
A Placido pattern with distinct rings featuring color, thickness, or separation differences, and marker features like gaps or markings, allowing for easier identification and analysis of distortions in the reflected pattern to determine corneal anomalies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard Placido pattern with equally spaced concentric rings is used, then the corneal surface shape can be determined through reflection analysis, but the pattern is difficult to analyze and distinguish individual rings
Solution Approach 1:
The patent applies local quality by introducing distinguishing features to specific rings rather than making all rings identical. Each ring can have unique properties such as different colors, thicknesses, or marker features at specific locations, allowing individual rings to be identified and analyzed separately, thereby reducing the overall difficulty of pattern analysis while maintaining measurement precision
Solution Approach 2:
The patent utilizes color changes as a distinguishing feature where different rings are displayed in different colors or with color variations. This allows the analysis system to easily differentiate between adjacent rings and track their reflections, significantly reducing the complexity of pattern analysis while preserving the ability to accurately determine corneal surface shape
2Adaptability or versatility
If equally spaced concentric rings are used in the Placido pattern, then the pattern can be projected onto the cornea, but it is difficult to identify specific rings in the reflected image
Solution Approach 1:
The patent applies preliminary action by pre-marking rings with distinguishing features before projection. Each ring is assigned unique identifiers such as color codes, thickness variations, or marker features at specific angular positions, so that when the pattern is reflected, the analysis system can immediately identify which ring corresponds to which corneal zone without losing identification information
Solution Approach 2:
The patent introduces asymmetry by placing marker features at specific non-uniform locations on rings or making ring properties asymmetric (e.g., different thickness on different sides). This breaks the perfect symmetry of equally spaced rings, enabling the system to distinguish individual rings and their orientations in the reflected pattern, thereby preventing loss of identification information
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
Enhances the ability to accurately identify and map corneal surface anomalies by simplifying pattern analysis, improving the precision of corneal topography determination.
Implementation Method 1
The anterior surface of the cornea reflects the Placido pattern
Data Source
AI summary
In certain embodiments, an ophthalmic system for determining the topography of the anterior surface of the cornea of an eye comprises an illuminator, a camera, and a computer. The illuminator illuminates the anterior surface of the cornea of the eye with a Placido pattern. The Placido pattern comprises a plurality of rings. A ring of the plurality of rings has a distinguishing feature that distinguishes the ring from an adjacent ring. The anterior surface of the cornea reflects the Placido pattern. The camera captures an image of the reflected Placido pattern. The computer: analyzes the image to detect a distortion of the ring that indicates an anomaly of the anterior surface of the cornea; identifies the ring of the plurality of rings according to the distinguishing feature of the ring; and generates the topography of the surface of the cornea that includes the anomaly.