Ophthalmic Microscope Confocal Refractometer Astigmatism Measurement
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Solution Overview
Problem
Current ophthalmic surgical microscopes with confocal refractometers cannot measure astigmatism and its axis position, limiting their suitability for intraoperative checks of toric intraocular lens orientation and being sensitive to stray light due to the absence of wavefront sensors.
Innovation Solution
An ophthalmic surgical microscope with an integrated confocal refractometer that measures spherical equivalent, astigmatism, and axis position without a wavefront sensor, using an adaptive optical module with adjustable cylindrical lenses to compensate for astigmatism and spherical equivalent, and an optical fiber for confocal imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a confocal refractometer without wavefront sensor is used, then stray light sensitivity is reduced and costs are lowered, but measurement capability is limited to spherical equivalent only
Solution Approach 1:
The measurement function is segmented into two independent modules: a confocal refractometer for spherical equivalent measurement and a separate astigmatism measurement device using cylindrical lenses. This segmentation allows each module to be optimized independently - the confocal module maintains low stray light sensitivity while the astigmatism module adds measurement capability without interfering with the confocal principle.
Solution Approach 2:
The surgical microscope is designed with multi-functionality by integrating both confocal refractometry and astigmatism measurement capabilities into a single system. The measurement beam path can be configured to perform either spherical equivalent measurement or astigmatism measurement, making the system versatile while maintaining the benefits of confocal design.
2Device complexity
If a confocal refractometer without wavefront sensor is used, then device complexity is reduced, but measurement precision is insufficient for astigmatism and axis position
Solution Approach 1:
Cylindrical lenses are introduced as intermediary optical elements in the measurement beam path to enable astigmatism measurement. These lenses mediate between the simple confocal refractometer design and the requirement for astigmatism measurement precision, adding the necessary optical functionality without requiring complex wavefront sensing technology.
3Adaptability or versatility
If cylindrical lenses are added to measure astigmatism, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The astigmatism measurement functionality using cylindrical lenses is merged with the existing confocal refractometer system by integrating them into a shared measurement beam path. This combining approach allows both measurement capabilities to coexist in a unified system rather than requiring separate independent devices, thereby managing complexity while maintaining versatility.
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 accurate measurement of astigmatism and axis position, reducing stray light sensitivity and costs, and facilitating intraoperative checks of toric intraocular lens orientation.
Implementation Method 1
an optical system (40), in particular a confocal optical system, which is configured as a refractometer for determining the refraction of an eye (12) of a patient
Implementation Method 2
measuring module (54), in particular including a light detector (56), which is configured to measure an intensity of measurement light (48) reflected back by the retina (16)
Implementation Method 3
an adaptive optical module (74, 76), which is adjustable to compensate the spherical equivalent of the ametropia of the eye (12) in the wavefront of a measurement light beam path (42) and to at least partly compensate an astigmatism with any axis position in the wavefront of the measurement light beam path (42)
Data Source
AI summary
An ophthalmic surgical microscope includes a main objective lens, through which an observation beam path passes, and a confocal optical system configured as a refractometer to determine the refraction of an eye. The optical system includes a measurement light source to generate a measurement light beam, a light detector to measure an intensity of measurement light and an optical unit to direct the measurement light beam onto the retina of the eye and to return measurement light reflected back at the retina to the light detector. The optical system includes an adaptive optical module (AOM) to modify a wavefront of the measurement beam path such that an intensity of the back-reflected measurement light changes. A spherical equivalent (SE) of the ametropia of the eye is determined based on a setting of the AOM, at which the measured intensity of the back-reflected measurement light has a maximum.