Binocular Refraction Measurement Using Pinhole Convergence Targets
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Solution Overview
Problem
Conventional ophthalmologic apparatuses face difficulties in accurately measuring convergence accommodation during binocular viewing due to simultaneous adjustments in focus and convergence.
Innovation Solution
An ophthalmologic apparatus with a visual-target presenting portion and an objective measurement optical system that allows for the presentation of visual targets to each eye separately, using pinhole plates at conjugate positions with the pupils, enabling accurate measurement of convergence accommodation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ophthalmologic apparatuses measure ocular information during binocular viewing with common fixation targets, then the measurement process is simplified, but the convergence accommodation cannot be properly measured due to simultaneous focus adjustment based on distance
Solution Approach 1:
The patent divides the measurement process into separate components: the visual target presenting portion that controls convergence position and the objective measurement optical system that measures refractive values. This segmentation allows independent control of convergence stimulation and measurement, enabling accurate convergence accommodation measurement without interference from distance-based focus adjustments.
Solution Approach 2:
The patent introduces pinhole plates as an intermediary element positioned at locations conjugate with the subject's pupils. These pinhole plates create artificial convergence conditions by limiting the entrance pupil, thereby stimulating convergence accommodation without requiring actual binocular viewing of distant targets. This intermediary mechanism isolates the convergence stimulus from distance-based accommodation cues.
2Measurement precision
If the apparatus uses pinhole plates at positions conjugate with pupils to adjust convergence position, then convergence accommodation can be accurately measured, but the device complexity increases
Solution Approach 1:
The visual target presenting portion is designed to perform multiple functions: it presents visual targets for normal refraction measurement and simultaneously acts as a convergence stimulus device by positioning pinhole plates at specific locations. This multi-functionality allows the same optical system to conduct both standard refraction measurements and convergence accommodation measurements without requiring entirely separate apparatuses.
Solution Approach 2:
The patent uses optical conjugation to create a virtual copy of the pinhole plate effect at the pupil plane. By positioning the pinhole plates at locations conjugate with the subject's pupils, the system creates an optical equivalent that stimulates convergence without requiring physical manipulation of the subject's eyes or complex mechanical adjustment mechanisms.
3Measurement precision
If visual targets are presented while changing convergence position, then convergence accommodation is stimulated, but the measurement becomes difficult without isolating convergence from distance-based focus adjustment
Solution Approach 1:
The patent applies local quality by positioning pinhole plates at specific locations within the optical system that are conjugate with the subject's pupils. This localized placement creates a specific optical effect at the pupil plane that stimulates convergence accommodation without affecting other parts of the measurement system. The pinhole plates act locally to modify the entrance pupil characteristics, thereby isolating the convergence stimulus from distance-based accommodation cues.
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 measurement of convergence accommodation by maintaining focus adjustments separate from convergence-induced changes, thereby accurately determining refractive values.
Implementation Method 1
with pinhole plates respectively disposed at positions conjugate with pupils of the left and right subject eyes
Implementation Method 2
pinhole plates respectively disposed at positions conjugate with pupils of the left and right subject eyes
Data Source
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AI summary
An ophthalmologic apparatus includes a visual-target presenting portion (41) that is configured to present visual targets (8) to left and right subject eyes (EL, ER), respectively; and an objective measurement optical system (6, 7) that is configured to objectively measure eye characteristics of the left and right subject eyes (EL, ER), respectively. The visual-target presenting portion (41) is configured to present the visual targets (8) while changing a convergence position (R, R1, R2), where two lines of sight (SL1, SR1, SL2, SR2) from positions of the left and right subject eyes (EL, ER) intersect, with pinhole plates (50) respectively disposed at positions conjugate with pupils of the left and right subject eyes (EL, ER). The objective measurement optical system (6, 7) is configured to obtain the objective refractive values of the left and right subject eyes (EL, ER), respectively, under a condition where the pinhole plates (50) are respectively disposed by the visual-target presenting portion (41) and the visual targets (8) presented at the convergence position (R, R1, R2) are binocularly fused.