Movable Lens for In-Focus Iris and Scleral Imaging
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Solution Overview
Problem
Eye measurement instruments struggle to capture clear, in-focus images of scleral blood vessels during eye examinations, as they are typically out of focus when the iris is in focus for accurate measurements, and using high f-number lenses compromises light collection efficiency and patient comfort.
Innovation Solution
An optical system with a movable optical element and actuator allows for shifting the focal plane to capture both iris and scleral blood vessel images contemporaneously, using green light for higher contrast and infrared for improved visibility, enabling registration of eye measurement data during subsequent treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical measurement instrument is focused on the iris for accurate measurements, then the measurement precision is improved, but the scleral blood vessels become out of focus
Solution Approach 1:
The patent employs a movable optical element (such as a lens or mirror) that can be dynamically adjusted along the optical axis to shift the focal plane. This dynamic adjustment allows the system to alternately focus on the iris for measurement and on the scleral blood vessels for imaging, resolving the contradiction between measurement precision and imaging focus by making the focal plane adjustable rather than fixed
2Adaptability or versatility
If the depth of focus is increased to encompass both iris and scleral blood vessels, then the adaptability is improved, but the light collection efficiency deteriorates due to large f-number
Solution Approach 1:
Rather than using a large f-number system to achieve extended depth of focus, the patent dynamically adjusts the focal plane position to match the specific measurement or imaging task. This allows the use of a smaller f-number optical system that maintains high light collection efficiency while achieving the necessary focus range through temporal separation of focusing tasks
Solution Approach 2:
The system periodically alternates between focusing on the iris for measurement and focusing on the scleral blood vessels for imaging. This periodic switching of focus targets allows both functions to be performed with high quality using a single optical system with good light collection efficiency
3Reliability
If ink marks are made on the eye for registration, then the reliability of registration is improved, but the ease of operation deteriorates due to added time and discomfort
Solution Approach 1:
The patent extracts and eliminates the need for ink marks by directly imaging the scleral blood vessels, which naturally exist on the eye surface. By using these inherent anatomical features as registration markers, the system achieves reliable registration without requiring additional procedures that would increase patient discomfort or examination time
4Ease of operation
If features on the iris are used for registration, then the ease of operation is improved, but the reliability deteriorates due to pupil dilation during surgery
Solution Approach 1:
The patent uses scleral blood vessels as an intermediary registration feature that remains stable throughout the surgical procedure. Unlike iris features that change with pupil dilation, the scleral vasculature remains relatively unchanged, providing a reliable reference frame that bridges the preoperative measurement phase and the intraoperative treatment phase
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 solution allows for accurate registration of eye measurement data using scleral blood vessels, enhancing the precision of procedures like LASIK and IOL implantation while maintaining patient comfort and efficient light collection.
Implementation Method 1
using green light for higher contrast
Implementation Method 2
infrared for improved visibility
Implementation Method 3
shifting the focal plane to capture both iris and scleral blood vessel images
Data Source
AI summary
An eye measurement instrument includes: an optical measurement subsystem for measuring an optical characteristic of an eye; an imaging system, including: a camera, an optical system including a movable optical element, and an actuator to move the movable optical element. When the movable optical element is moved into a first position outside an optical path between the eye and the camera, then the optical system focuses a first feature of the eye at the camera, and the camera is configured to capture a first image of the eye, and when the movable element is moved in a second position in the optical path then the optical system focuses a second feature of the eye, different from the first feature, at the camera, and the camera captures a second image of the eye.