Objective Phoropter System Wavefront Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing combination optical refraction measurement systems face challenges such as increased laser reflection from phoropter elements, degrading the laser beam mode, and difficulty in accurately measuring residual aberrations, especially with higher order aberrations, due to subjective phoropter measurements and superfluous reflections.
Innovation Solution
A system combining phoropter measurements with wavefront analysis using a Shack-Hartmann array, where the wavefront analyzer measures residual aberrations after initial phoropter correction, with adjustments to prevent corneal reflections from overwhelming retinal reflections, and includes features like lateral pupil distance adjustment, angular tilt mechanisms, and automatic pupil distance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the laser illumination source is deflected into the measurement beam path through the phoropter elements, then the wavefront analysis can be performed, but the laser reflection from phoropter elements increases and degrades the laser beam mode
Solution Approach 1:
The system separates the illumination function from the measurement function by using two distinct beam paths. The illumination beam enters the eye through one path while the measurement beam enters through a different path, avoiding interference between the two functions and preventing laser reflection from phoropter elements
Solution Approach 2:
A beam splitter is introduced as an intermediary component to direct the illumination beam into the eye without passing it through the phoropter elements. The beam splitter enables the illumination path to be independent from the measurement path, eliminating the harmful reflections while maintaining measurement capability
2Ease of operation
If subjective phoropter measurement is used to correct refractive errors, then initial correction can be achieved, but accurate measurement of residual aberrations is difficult due to subjective response limitations
Solution Approach 1:
The system uses objective wavefront measurement as feedback to verify and refine the subjective phoropter measurement. The wavefront analyzer provides quantitative data on residual aberrations, allowing the system to objectively assess whether the subjective correction is adequate and make precise adjustments
Solution Approach 2:
The system uses the patient's own eye as the measurement target for wavefront analysis, eliminating the need for external calibration standards. The eye itself provides the reference for measuring residual aberrations after phoropter correction
3Adaptability or versatility
If the phoropter and wavefront analyzer are combined in a single system, then both measurements can be performed, but the system complexity increases and alignment becomes more difficult
Solution Approach 1:
The combined system is designed with separate, independent optical paths for illumination and measurement that diverge early in the beam trajectory. This segmentation allows each subsystem to be optimized independently while maintaining overall system integration, reducing alignment complexity
Solution Approach 2:
The system uses spatial separation in different dimensions to resolve path interference. By directing beams at different angles and using separate entry points to the eye, the system accommodates multiple measurement functions without requiring precise co-alignment of all optical components
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 more accurate and objective determination of refractive errors, reducing the need for precise subjective phoropter measurements and enabling better correction of higher order aberrations, while minimizing reflections and optimizing beam alignment for improved measurement accuracy.
Implementation Method 1
The difference between the aberrated wavefront emitted from the eye and a planar undistorted wavefront is measured using a wavefront analysis system, such as that based on a Shack-Hartmann array
Implementation Method 2
The output of such an instrument is a map of the refractive properties across the eye, which can be used to determine the form and strength of spectacle lenses for correction of the aberration measured
Implementation Method 3
part of the incident laser light may be reflected back towards the Shack-Hartmann detection array, and the intensity of this reflected light may be substantially larger than that of the weak reflection from the retina
Data Source
Figure 1
Figure 2~5
Figure 6
AI summary
Systems for performing combined phoropter and refractive measurements to ascertain the aberrations present in the eye of a subject. The systems use a pair of phoropter wheel assemblies, one for each eye, each assembly comprising a number of lens wheels incorporating the series of lenses and wedges required to compensate for a range of refractive vision aberrations. The vision of each eye is corrected by a combination of a subjective phoropter measurement, iteratively performed with an objective wavefront analysis measurement to determine the residual aberrations existing after the initial phoropter correction. The system is able to automatically align the axes of each wavefront analyzer with is corresponding eye, by means of centering the pupil image in the wavefront analyzer camera, and to determine the pupil distance. By changing the focusing point on the wavefront analyzer of the light reflected from the eye, the corneal profile can be measured.