Ophthalmic Alignment Pattern for Crystalline Lens Working Distance
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Solution Overview
Problem
Existing ophthalmic instruments face challenges in aligning with a patient's eye, particularly for examinations behind the iris, leading to issues like dim and/or vignetted images and spurious reflections due to variations in eye structures and distances between the cornea and crystalline lens.
Innovation Solution
An alignment method using optical radiation, such as visible and/or infrared light, forms a predetermined alignment pattern on a target plane, and a reflection pattern is detected to adjust the alignment based on deviations from the predetermined pattern, ensuring accurate positioning of the ophthalmic instrument relative to the eye.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ophthalmic instrument is positioned without precise alignment guidance, then the operation is simple and quick, but the alignment accuracy deteriorates leading to dim/vignetted images and spurious reflections
Solution Approach 1:
The patent implements feedback by projecting an alignment pattern onto the eye and detecting its reflection. The system compares the reflected pattern's position and shape against expected values to determine alignment accuracy, providing real-time feedback to guide the user in adjusting the instrument position until optimal alignment is achieved.
Solution Approach 2:
The alignment pattern serves as an intermediary element between the instrument and the eye. This pattern is projected onto the eye's surface and its reflection is analyzed to indirectly determine alignment status, acting as a mediator that translates complex optical alignment requirements into observable pattern deviations.
2Measurement precision
If the alignment pattern is projected to determine precise alignment, then the alignment accuracy is improved, but the examination time increases due to additional alignment steps
Solution Approach 1:
The alignment pattern is projected onto the eye before the actual examination begins. This preliminary action establishes the correct instrument position and optical axis alignment in advance, ensuring that subsequent imaging is performed from the optimal position without requiring time-consuming adjustments during the examination.
Solution Approach 2:
The patent replaces manual trial-and-error mechanical positioning with an optical measurement system. Instead of physically adjusting the instrument based on visual inspection, the system uses optical pattern projection and reflection analysis to automatically determine alignment, substituting mechanical adjustment with optical feedback.
3Adaptability or versatility
If the instrument is aligned for patients with varying eye structures, then the adaptability is improved, but the difficulty of detecting and measuring alignment increases due to individual variations
Solution Approach 1:
The alignment pattern and detection method are designed to be universal and applicable to all patients regardless of their individual eye structures. The same pattern projection and reflection analysis technique works for diverse anatomical variations, eliminating the need for patient-specific calibration or multiple alignment methods.
Solution Approach 2:
The system accounts for individual eye structure variations by monitoring changes in the reflected alignment pattern's parameters (position, shape, orientation). These parameter changes in the reflection provide information about the specific patient's anatomy, allowing the system to adapt the alignment determination to individual variations while using the same fundamental method.
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 method enhances alignment accuracy, minimizing image artifacts and reflections, allowing for clear and focused imaging of the eye's interior, particularly the fundus, by guiding the user to adjust the instrument's position for optimal working distance.
Implementation Method 1
an alignment method using optical radiation, such as visible and/or infrared light, forms a predetermined alignment pattern on a target plane, and a reflection pattern is detected
Data Source
AI summary
An ophthalmic apparatus comprises an alignment arrangement, which outputs rays of alignment light of a first alignment pattern in a converging manner toward a first target plane, forms a predetermined reflection pattern of the first alignment pattern on said first target plane based on the convergence, causes the rays of the alignment light to have an alignment light waist zone that includes the first target plane based on the convergence, causes a reflection pattern of the first alignment pattern outside the first target plane to deviate from the predetermined reflection pattern based on the convergence. A communication interface of the ophthalmic apparatus outputs information on the reflection pattern of the first alignment pattern reflected from said a posterior surface of the crystalline lens of the eye when the ophthalmic apparatus is directed toward the eye for guiding and/or controlling a user based on the reflection pattern of the first alignment pattern that is varying with the position of the posterior surface of the crystalline lens on said posterior surface to find the working distance from the eye where the predetermined shape of the first alignment pattern is on said posterior surface.