Dynamic Video Fixation Target for Accurate Aberrometer Measurements
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Solution Overview
Problem
Current methods for correcting corneal distortions, such as those caused by keratoconus, are inadequate as they cannot accurately measure and stabilize contact lenses on the eye, leading to sub-optimal vision correction.
Innovation Solution
The development of an instrument, NextWave™, that uses wavefront sensors to measure aberrations and guide the customization of contact lenses, ensuring accurate fitting and dynamic wavefront sensor measurements through a trial contact lens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional wavefront sensors are used with fixed fixation targets, then the measurement system is simple, but the patient cannot maintain stable fixation during measurement, leading to measurement errors
Solution Approach 1:
The fixation target is changed from a static image to a dynamic video display that can change content, size, and position. The video target can dynamically adjust to match the patient's pupil size and can be repositioned to maintain fixation stability, thereby improving measurement accuracy without requiring overly complex mechanical adjustment mechanisms
Solution Approach 2:
The fixation target parameters (size, luminance, position, content) are made variable and可调 through video display technology. The target can be enlarged or reduced, moved to different locations, and its luminance can be adjusted to optimize patient fixation stability and accommodate different pupil sizes, directly improving measurement precision
2Stability of the object's composition
If the fixation target is made larger to improve patient fixation stability, then fixation stability improves, but the target may extend beyond the pupil aperture and cause measurement errors
Solution Approach 1:
The video fixation target can dynamically change its size during the measurement process. It can be enlarged to improve fixation stability, then reduced to fit within the pupil aperture before wavefront measurement, and potentially enlarged again for subsequent measurements. This dynamic adjustment allows the system to optimize for both fixation stability and measurement accuracy at different stages
Solution Approach 2:
The fixation target size can be periodically adjusted between larger (for fixation stability) and smaller (for measurement accuracy) states. This periodic adjustment allows the patient to maintain stable fixation on a larger target while ensuring the target remains within the optical measurement aperture when actual wavefront data is collected
3Stability of the object's composition
If the video target is enlarged to improve fixation stability, then fixation stability improves, but diffraction effects increase and reduce image quality
Solution Approach 1:
The video target size is dynamically adjusted based on the measurement phase. During fixation acquisition, the target is enlarged to improve stability. During actual wavefront measurement, the target is reduced to a size that minimizes diffraction effects while maintaining adequate fixation stability, thereby balancing fixation requirements with optical quality requirements
4Device complexity
If a single video target is used for all measurements, then the system is simple, but it cannot accommodate different pupil sizes and measurement conditions
Solution Approach 1:
The video fixation target parameters (size, luminance, position) are made variable to accommodate different measurement conditions. The target size can be adjusted to match different pupil sizes, luminance can be modified for different lighting conditions, and position can be changed to optimize fixation. This parameter variability provides adaptability without requiring multiple physical targets
Solution Approach 2:
A single video display device serves multiple functions: it can display different target sizes, different luminance levels, different target positions, and different target content. This multi-functionality allows the system to adapt to various pupil sizes and measurement conditions using one versatile component rather than requiring multiple specialized targets
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 allows for the reduction of RMS aberrations, improving visual acuity and image quality by providing a customized contact lens that accurately corrects higher-order aberrations.
Implementation Method 1
A small spot of light is projected onto the retina and the scattered light is collected by the lens and cornea and imaged onto a wavefront sensor
Implementation Method 2
The fixation target is replaced with a video target that displays an image to the patient
Data Source
AI summary
This invention relates to methods and devices for designing customized contact lenses, by initially making dynamic wavefront sensor measurements through a trial contact lens that is fitted on an eye, and then calculating a WaveFront Guided (WFG) correction to be applied to the trial contact lens that reduces the RMS level of aberrations as much as practically possible. The output of the wavefront correction program is a customized lathe file that the manufacturer can use to make customized contact lenses on a lathe. The method works best for soft contact lenses and scleral lenses.