Transparent Trephine Casing for Parallax-Free Blade Alignment
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Solution Overview
Problem
Existing vacuum trephines in ophthalmic surgery face challenges in accurately setting the zero position of the blade due to the opaque materials used in their construction, leading to parallax errors during alignment.
Innovation Solution
The trephine apparatus features an outer and inner casing made of non-opaque, transparent materials, allowing direct edge-on visualization of the blade and basal elements, enabling precise alignment without parallax errors, and includes a cylindrical trephine blade that can be raised and lowered for accurate cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the casing and inner tube are made of opaque surgical grade stainless steel, then the structural strength and durability are improved, but the ability to accurately set the zero position of the blade is worsened due to parallax errors
Solution Approach 1:
The outer casing is made transparent instead of opaque, fundamentally changing the optical property of the component. This allows the blade and inner tube base to be viewed directly through the casing, eliminating parallax errors in zero position alignment while maintaining structural integrity through proper material selection
Solution Approach 2:
The transparent outer casing acts as an intermediary that allows optical access to the blade and inner tube base without interfering with the mechanical structure. It serves as both a protective enclosure and a visual interface, enabling simultaneous structural and measurement functions
2Reliability
If the blade is retracted insufficiently, then the vacuum seal cannot be obtained, but if the blade is retracted too much, then the cutting depth is reduced
Solution Approach 1:
The spoked wheel mechanism is replaced with a micrometer screw mechanism, substituting a coarse mechanical adjustment system with a precision threaded system. This allows for fine-tuned control of blade retraction distance, enabling the blade to be positioned at the exact correct depth to achieve both reliable vacuum seal and precise cutting depth
Solution Approach 2:
The adjustment mechanism changes from discrete spoked wheel increments to continuous micrometer screw adjustment. This parameter change enables precise control of the blade position, allowing the operator to set the exact retraction distance needed for reliable vacuum seal while maintaining the desired cutting depth
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 design allows for accurate and easy setting of the zero position, reducing the risk of parallax errors and improving the precision of blade alignment, enhancing the overall accuracy and safety of the surgical procedure.
Implementation Method 1
at least the lower end element of the outer casing being made of a non-opaque (i.e., substantially transparent or translucent) material
Implementation Method 2
When a vacuum is applied to the cylindrical space between the outer casing and the inner tube, the casing becomes attached to the epithelium by suction
Implementation Method 3
the casing becomes attached to the epithelium by suction, thereby preventing movement between the casing and the cornea
Data Source
AI summary
Trephine apparatus has an outer casing with means defining a substantially cylindrical passage, or aperture, opening at a substantially circular lower end element, and an inner, substantially cylindrical tube having a bore opening at a substantially circular lower end element, the lower end element of the inner tube being upwardly spaced, or recessed, from the lower end element of the outer casing within the passage. A substantially cylindrical trephine blade is mounted within the bore of the inner tube by means that is so constructed as to enable raising and lowering of the blade relative to the end elements of the outer casing and the inner tube. At least a lower end element of the outer casing, or a base portion including it, is made of a non-opaque material, enabling edge-on viewing of the basal element of the inner tube and the blade, such as by use of a microscope, without parallax between the blade and the basal element of the inner tube. The zero position of the blade can be set easily and highly accurately, in a manner that is not possible with existing vacuum trephine assemblies.