Ophthalmic Apparatus Pupil Diameter Correction
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Solution Overview
Problem
Ophthalmic apparatuses face inaccuracies in measuring visual function responses due to varying pupil diameters, which affect the amount of light energy entering the eye, leading to incorrect measurement results when stimulus light is emitted under a constant background light.
Innovation Solution
An ophthalmic apparatus that computes sensitivity values by using a memory database to correct virtual sensitivity values based on pupil diameter measurements, adjusting the stimulus light intensity according to a standard pupil diameter, and employing a shape parameter rate to ensure accurate measurement results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stimulus light of predetermined energy is emitted under constant background light, then measurement can be performed, but measurement precision deteriorates due to varying pupil diameters affecting actual light energy entering the eye
Solution Approach 1:
The system performs preliminary measurement of the pupil diameter before the sensitivity test, and pre-calculates the appropriate stimulus light energy based on the measured pupil size. This preliminary action ensures that the actual light energy entering the eye is corrected according to the individual's pupil characteristics, thereby maintaining measurement precision while enabling the test to proceed.
Solution Approach 2:
The system changes the stimulus light energy parameter dynamically based on the measured pupil diameter. Instead of using fixed predetermined energy, the stimulus energy is adjusted according to the ratio between the measured pupil area and standard pupil area, compensating for individual variations in pupil size and ensuring accurate sensitivity measurements.
2Device complexity
If sensitivity is computed only by area rate to standard pupil diameter, then computation is simplified, but measurement precision deteriorates when background light is present
Solution Approach 1:
The system introduces an intermediary correction factor based on the measured pupil diameter to bridge the simplified area rate computation and the actual light energy required. This intermediary parameter allows the system to maintain computational simplicity while achieving precise sensitivity measurements by adjusting the stimulus energy according to individual pupil characteristics.
Data Source
AI summary
A virtual sensitivity value which is obtained, variously changing a pupil diameter is measured in advance for many examinees, and volume of correction which is necessary at the time when the sensitivity value is corrected into one in a standard pupil diameter is stored as correction volume database. An apparatus has measurement means for measuring the pupil diameter of the eye to be examined, computing means for computing a shape parameter rate of the measured pupil diameter to the standard pupil diameter, and judgment means for computing volume of correction by referring to the correction volume database from the shape parameter rate and correcting the virtual sensitivity value obtained by measurement of the eye to be examined and for judging a sensitivity step of the eye to be examined.