Defocus Curve Measuring Apparatus for Multifocal IOLs
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Solution Overview
Problem
Current methods for measuring the defocus curve of multifocal intraocular lenses are cumbersome, inaccurate, and cannot be applied directly to patients, as they require repeated visual acuity measurements and cannot account for the refractive errors and multiple focuses of diffractive intraocular lenses.
Innovation Solution
A defocus curve measuring apparatus that uses a light source, a first lens to refract light to infinity, a beam splitter for polarization, an intraocular lens module to refract light, and a camera to capture s-polarized light reflected from the retina, allowing for objective measurement of the defocus curve from outside the eye.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If repeated visual acuity measurements using the fogging method are performed, then the defocus curve can be obtained, but the measurement process becomes cumbersome and time-consuming for patients and examiners
Solution Approach 1:
The patent replaces the manual fogging method with an automated optical measurement system using a Badal optometer. The system uses optical components (lenses, mirrors, light sources) to automatically vary defocus and measure visual acuity across multiple distances, eliminating the need for manual lens insertion and repeated subjective patient responses. This mechanical-to-optical substitution achieves both speed and objectivity.
Solution Approach 2:
The system enables objective measurement without requiring continuous patient feedback. By using optical detection methods (such as detecting light reflection from the retina or using contrast sensitivity measurements), the apparatus can automatically determine visual acuity at each defocus level without relying on patient subjectivity, thereby reducing measurement time and improving consistency.
2Object-affected harmful factors
If infrared rays are used for patient safety in autorefractometry, then patient safety is improved, but diffractive intraocular lenses designed for visible light cannot be measured accurately
Solution Approach 1:
The patent changes the wavelength parameter of the light source from infrared to visible light range. By using visible light (such as LED or laser sources in the 400-700nm range), the system matches the design wavelength of diffractive intraocular lenses, enabling accurate measurement of their optical properties while still maintaining patient safety through controlled exposure levels.
Solution Approach 2:
The system uses visible light as an intermediary that interacts with the diffractive IOL's optical structure. The light passes through the IOL, and the diffractive patterns are detected by the measurement system, allowing accurate characterization of the lens's multiple focal points without requiring the patient to subjectively report vision quality.
3Measurement precision
If the optical bench test method is used to obtain the defocus curve, then objective measurement is achieved, but the method cannot be applied to patients because the camera cannot be placed inside the eye behind the intraocular lens
Solution Approach 1:
Instead of placing the camera inside the eye behind the IOL, the patent inverts the measurement approach by placing the camera outside the eye and using optical components (such as a retroreflector or mirror system) to capture light that has passed through the IOL. This external measurement configuration maintains objectivity while enabling patient applicability.
Solution Approach 2:
The system introduces an optical intermediary (such as a retroreflector, mirror, or relay lens system) that allows light to travel from the external camera, through the IOL, and back to the camera. This intermediary enables the capture of optical information from behind the IOL without requiring physical access to the intraocular space, thereby maintaining both objectivity and patient compatibility.
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 automatic and objective measurement of the defocus curve for multifocal intraocular lenses, overcoming the limitations of existing methods by providing a non-invasive and accurate assessment.
Implementation Method 1
a first lens that infinitely refracts the focus as the light source passes through it
Implementation Method 2
a beam splitter having a polarization function that passes p-polarized light of the light source that has passed through the first lens and reflects s-polarized light
Implementation Method 3
an intraocular lens module that refracts the light source that has passed through the beam splitter as it passes, thereby determining the focus
Implementation Method 4
a camera that captures an image of s-polarized light reflected by the beam splitter after the light source reflected from a retina passes through the intraocular lens module
Data Source
AI summary
Disclosed is a defocus curve measuring apparatus for a multifocal intraocular lens capable of automatically measuring an objective defocus curve. A defocus curve measuring apparatus for a multifocal intraocular lens according to an aspect of the present invention may include a light source passed through a target image for focusing; a first lens that infinitely refracts the focus as the light source passes through it; a beam splitter having a polarization function that passes p-polarized light of the light source that has passed through the first lens and reflects s-polarized light; an intraocular lens module that refracts the light source that has passed through the beam splitter as it passes, thereby determining the focus; and a camera that captures an image of s-polarized light reflected by the beam splitter after the light source reflected from a retina passes through the intraocular lens module.