Visual Axis Identification via Retinal Image Coincidence
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Solution Overview
Problem
Current methods for determining the visual axis of the eye are inaccurate, particularly for compromised or unusually shaped eyes, leading to suboptimal placement of intraocular lenses and other ophthalmic treatments.
Innovation Solution
A visual axis identification system using a fixation light source with multiple fixation light spots and a camera to capture digital images of the iris plane, allowing for precise determination of the visual axis by aligning the optical center of the camera with the visual axis of the eye.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the visual axis location is approximated to be halfway between the pupil center and the corneal vertex, then the measurement process is simple, but the measurement precision is poor
Solution Approach 1:
The patent changes the measurement parameters from simple geometric approximation (halfway point) to multi-point coordinate detection using digital imaging. The system captures images at multiple positions along the optical axis and uses coordinate analysis to determine the visual axis intersection point, transforming a single-point estimation into a multi-parameter measurement process that significantly improves accuracy.
Solution Approach 2:
The patent introduces digital imaging technology as an intermediary between the eye and the measurement process. By using a camera to capture images of the iris plane and analyzing the coordinates of visual landmarks (pupil center, corneal vertex, etc.), the system creates an intermediate digital representation that enables precise calculation of the visual axis location without direct physical measurement.
2Device complexity
If conventional approximation methods are used for visual axis determination, then the device complexity is low, but the reliability of ophthalmic treatment placement is compromised
Solution Approach 1:
The patent replaces mechanical measurement methods (physical alignment tools, manual landmark identification) with an optical-digital system. A camera captures images of the eye, and software algorithms automatically identify landmarks and calculate the visual axis intersection point, eliminating the need for complex mechanical alignment devices while significantly improving placement reliability.
Solution Approach 2:
The patent creates a digital copy of the eye's optical structures through imaging. By capturing images of the iris plane and extracting coordinate information from these digital copies, the system can perform repeated measurements and calculations without physically touching or disturbing the eye, thereby improving both reliability and patient comfort.
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 accurate and precise identification of the visual axis, improving the efficacy of ophthalmic procedures such as presbyopic treatments and refractive surgeries by ensuring accurate lens alignment and positioning.
Implementation Method 1
directing a fixation light towards the patient's eye, where the fixation light has two or more fixation light spots formed at different positions along an optical axis of a fixation light source that correspond with two or more images formed on or near a retina of the patient's eye
Implementation Method 2
One or more digital images of an iris plane of the patient's eye are captured by a first camera
Data Source
AI summary
The devices and methods described herein provide improved methods for accurately identifying and locating the visual axis of the eye and its intersection with the iris plane. In one embodiment, a visual axis identification system includes a fixation light source, a camera, and a processing system. During operation thereof, the patient focuses their gaze onto two or more fixation light spots provided by the fixation light source upon an optical axis thereof, which creates two or more corresponding images on or near to the patient's retina. The patient's head is then rotated relative while the patient continuously maintains their gaze on the fixation light spots. The patient's visual axis may be located by determining the location of the optical axis of the fixation light source relative to the patient's eye when the centers of the multiple images coincide in the patient's view.