Microscope-Mounted Keratometer for Intraoperative Astigmatism Measurement
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Solution Overview
Problem
Current cataract surgery biometry methods lack accuracy, particularly in intraoperative astigmatism measurement, leading to poor surgical outcomes and the need for post-surgery glasses due to insufficient tools for real-time intraoperative measurements.
Innovation Solution
A detachable keratometer mounted under a surgical microscope, utilizing a Placido ring, video camera, beamsplitter, and processor for real-time refractive characteristic determination and digital image enhancement to guide intraocular lens alignment, with integrated optical coherence tomography for posterior corneal surface curvature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional biometry methods are used for cataract surgery, then the surgical process can be completed, but measurement accuracy is insufficient leading to poor surgical outcomes
Solution Approach 1:
The patent replaces traditional mechanical contact-based keratometry with optical Placido ring reflection methodology. The system uses a series of concentric Placido rings projected onto the cornea, with their reflections captured by a camera to calculate corneal curvature through optical analysis rather than mechanical contact, thereby improving measurement accuracy and reliability
Solution Approach 2:
The patent creates digital copies of corneal surface geometry through Placido ring image capture and processing. The system generates topographic maps and curvature data by analyzing the reflected ring patterns, producing accurate digital representations of corneal shape that can be used for precise IOL power calculation without physical contact
2Loss of time
If pre-surgery biometry is performed two weeks before surgery, then measurements can be obtained, but cyclotorsion causes eye rotation and registration errors that reduce accuracy
Solution Approach 1:
The patent performs keratometry measurements immediately during surgery rather than pre-surgery, eliminating the time gap that allows cyclotorsion to occur. The system is ready and calibrated beforehand, allowing instant measurement at the critical moment when the eye is in its final surgical position, thus preventing registration errors from eye rotation
Solution Approach 2:
The system provides real-time feedback of corneal curvature and astigmatism measurements during surgery. The immediate measurement and display of results allow the surgeon to adjust IOL alignment based on actual intraoperative conditions, creating a closed-loop system that eliminates delays and ensures accuracy
3Measurement precision
If microscope-mounted keratometer is used for intraoperative measurement, then real-time accuracy improves, but device size and complexity increase
Solution Approach 1:
The patent integrates multiple functions into a single microscope-mounted device. The keratometer combines Placido ring projection, image capture, corneal curvature calculation, and topographic mapping capabilities within the existing surgical microscope platform, allowing one device to perform multiple diagnostic and surgical guidance functions
Solution Approach 2:
The system merges the keratometer optics with the surgical microscope optical path. By combining the Placido ring light source, beamsplitter, and camera into the microscope's illumination and imaging system, the patent eliminates separate standalone devices and reduces overall system complexity while maintaining measurement capabilities
4Device complexity
If visual comparison with reticle is used for ring measurement, then the system can be simple, but measurement precision and automation are insufficient
Solution Approach 1:
The patent replaces manual visual comparison with automated digital image processing. The camera captures digital images of the Placido ring reflections, and computer algorithms automatically calculate corneal curvature from the ring patterns, eliminating subjective visual estimation and improving precision through systematic digital analysis
Solution Approach 2:
The system creates digital copies of the Placido ring images and uses image processing algorithms to analyze the reflected patterns. By converting optical information into digital data that can be systematically processed, the system achieves higher measurement precision while maintaining relatively simple hardware
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
Enables precise, real-time intraoperative measurements, reducing errors and improving surgical outcomes by providing accurate astigmatism alignment and IOL placement, thus minimizing post-surgery refractive errors.
Implementation Method 1
When light reflects from human eye there are four reflections, known as Purkinje images 1-4, coming from anterior cornea (Purkinje 1 image), posterior cornea (Purkinje 2 image), anterior lens (Purkinje 3 image) and posterior lens (Purkinje 4 image). Measuring of radii of corneal curvature (Ks) is traditionally based on a well-known Placido keratometry technology
Implementation Method 2
a beamsplitter directing a Purkinje image of the Placido ring to the video camera
Implementation Method 3
a fixation light directing a beam for patient eye fixation, fixation confirmation or creating a red reflex effect to enhance IOL imaging and cataract visualization
Implementation Method 4
a processor configured to determine the refractive characteristics and keratometer parameters of the patient's eye and to execute a digital image enhancement method to outline IOL features to help IOL alignment
Implementation Method 5
a digital display displaying the keratometer parameters and surgical guidance information for a surgeon
Data Source
AI summary
A keratometer for intra-surgery measurements mounted under a surgical microscope includes a Placido ring illuminating a patient's eye; a video camera; a beamsplitter directing a Purkinje image of the Placido ring to the video camera; a fixation light directing a beam for patient eye fixation, fixation confirmation or creating a red reflex effect to enhance IOL imaging and cataract visualization; a processor configured to determine the refractive characteristics and keratometer parameters of the patient's eye and to execute a digital image enhancement method to outline IOL features to help IOL alignment; and a digital display displaying the keratometer parameters and surgical guidance information for a surgeon.