Ophthalmological measurement apparatus and measurement method
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Solution Overview
Problem
Conventional ophthalmological measurement apparatuses for determining the axial length of the eye require differently dimensioned optical acquisition systems for interferometric measurements, leading to increased hardware complexity and difficulty in distinguishing between intraocular distances such as anterior chamber depth and lens thickness, and are prone to errors due to eye movements.
Innovation Solution
An ophthalmological measurement apparatus combining an optical interferometric system for determining the retina's relative position and a non-interferometric system for determining the cornea's relative position, allowing for simultaneous and unique determination of the axial eye length without the need for differently dimensioned optical acquisition systems, and enabling the measurement of anterior chamber depth and lens thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interferometric measurement systems are used to determine both cornea and retina positions, then measurement precision is improved, but device complexity increases due to requiring differently dimensioned optical acquisition systems
Solution Approach 1:
The measurement system is segmented into two independent subsystems: an interferometric measurement system for retina position determination and a non-interferometric measurement system for cornea position determination. This segmentation allows each subsystem to be optimized for its specific function without requiring complex differently dimensioned optical acquisition systems, thereby reducing overall device complexity while maintaining measurement precision.
Solution Approach 2:
A beam splitter is introduced as an intermediary component to separate the light paths for cornea and retina measurements. The beam splitter directs light reflected from the cornea to the non-interferometric measurement system and light reflected from the retina to the interferometric measurement system, enabling simultaneous measurements without requiring complex integrated optical systems.
2Measurement precision
If interferometric measurement is used for both cornea and retina, then relative position determination is improved, but the ability to distinguish unique intraocular distances deteriorates when more than two optical interfaces are present
Solution Approach 1:
The measurement function is segmented between interferometric and non-interferometric systems based on the specific measurement requirements. The interferometric system provides precise relative position determination for the retina, while the non-interferometric system provides absolute position determination for the cornea. This segmentation enables unique identification of intraocular distances by combining relative and absolute position information from different measurement principles.
Solution Approach 2:
The measurement approach changes from purely interferometric to a hybrid approach combining interferometric and non-interferometric measurement parameters. By utilizing both relative position (interferometric) and absolute position (non-interferometric) parameters, the system can uniquely determine multiple intraocular distances including anterior chamber depth and lens thickness without the ambiguities that arise when using only interferometric measurement.
3Reliability
If simultaneous acquisition of cornea and retina is implemented, then reliability against eye movement errors is improved, but hardware outlay increases due to requiring two differently dimensioned optical systems
Solution Approach 1:
The optical acquisition system is segmented into two specialized subsystems with different dimensional characteristics optimized for their respective measurement targets. The interferometric measurement system is configured for retina detection while the non-interferometric measurement system is configured for cornea detection. This segmentation enables simultaneous acquisition without requiring a single complex system to handle both measurement types, thereby reducing overall hardware complexity while maintaining reliability.
4Adaptability or versatility
If differently dimensioned optical acquisition systems are used for cornea and retina, then measurement coverage is improved, but manufacturing cost and hardware outlay increase
Solution Approach 1:
The measurement system is divided into two independent measurement chains that can be manufactured and calibrated separately. The interferometric measurement system for retina and the non-interferometric measurement system for cornea are designed as modular components with standardized interfaces. This segmentation simplifies manufacturing processes and reduces costs compared to developing a single complex differently dimensioned optical system, while maintaining comprehensive measurement coverage.
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 simplifies hardware requirements, reduces measurement errors from eye movements, and allows for precise determination of axial eye length, anterior chamber depth, and lens thickness, while providing cost advantages over complex interferometric systems.
Implementation Method 1
conventional apparatuses for the interferometric measurement of the axial eye length, in which laser beams having a parallel beam profile converging on the retina are radiated onto the eye
Implementation Method 2
the light reflected by the cornea is reflected divergently through the cornea
Data Source
AI summary
An ophthalmological measurement apparatus (10) for determining the axial length (LA) of an eye (4) includes an optical interferometric first measurement system (1) for determining a relative position (A) of the retina (41) of the eye (4), a non-interferometric second measurement system (2) for determining a relative position (B) of the cornea (42) of the eye (4), and processing means (3) for determining the axial length (LA) of the eye (4) on the basis of the relative position (A) of the retina (41) and of the relative position (B) of the cornea (42). The design of the ophthalmological measurement apparatus (10) with an interferometric and a non-interferometric measurement system for a different measuring range in each case on a measurement axis (z) enables the substantially simultaneous determination of the relative positions (A, B) both of the cornea (42) and of the retina (41) without this requiring differently dimensioned optical acquisition systems for determining interference patterns of light reflected at the retina (41) and at the cornea (42).