Windowless Cannula Assembly With Undercut Hub and Concave Septum
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Solution Overview
Problem
Existing cannula assemblies for ophthalmic surgery face challenges such as high insertion forces due to thick distal ends and flat valve septums, which can lead to leakage and difficulty in instrument insertion, especially when intraocular pressure exceeds ambient pressure.
Innovation Solution
A windowless cannula assembly with a hub featuring an undercut and relief cutouts, a thin-wall section, and a concave septum, allowing for press-fitting and easier instrument insertion, while maintaining a secure seal and reducing material instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the distal end of the cannula has a thick wall structure, then the cannula provides structural strength, but it requires undesirably high insertion force to pass through the micro-incision
Solution Approach 1:
The cannula is divided into distinct sections with different wall thicknesses: a thicker proximal section for structural strength and a thinner distal section for easy insertion. This segmentation allows each part to fulfill its specific functional requirement without compromise.
Solution Approach 2:
The cannula features non-uniform wall thickness distribution, with the thinnest wall located at the distal tip where insertion is most difficult. This local quality optimization ensures that material is concentrated where needed for strength while minimizing resistance at the insertion point.
2Device complexity
If the valve septum has a flat top face that is flush with the hub, then the assembly is compact, but it resists instrument insertion and may leak when intraocular pressure exceeds ambient pressure
Solution Approach 1:
The valve septum top face is changed from flat to convex (curved outward). This curvature creates a rounded surface that facilitates instrument insertion by reducing contact area and pressure concentration, while the convex shape also helps seal better against pressure differentials.
Solution Approach 2:
The valve septum is positioned at a different height level than the hub top face, creating a stepped configuration. This dimensional change provides a distinct insertion surface that is easier to access and insert instruments into, while maintaining the sealing function.
3Illumination intensity
If the valve septum is translucent, then the appearance is aesthetic, but it makes it difficult to guide instruments to the center of the valve septum
Solution Approach 1:
The valve septum incorporates a visual indicator (such as a colored ring or marking) that contrasts with the translucent material. This color change provides a clear visual target for instrument alignment while maintaining the aesthetic translucent appearance of the overall component.
Solution Approach 2:
A specific asymmetric marking or feature is added to the otherwise symmetric translucent valve septum. This asymmetric element creates a unique visual reference point that guides instrument insertion to the correct location, breaking the symmetry that would otherwise make alignment difficult.
4Reliability
If the hub and cannula require precise clocking alignment during assembly, then the connection is secure, but the assembly process becomes difficult
Solution Approach 1:
The hub and cannula incorporate asymmetric alignment features such as keys, slots, or shaped interfaces that automatically guide proper orientation during assembly. This asymmetric design ensures secure, precisely aligned connections while eliminating the need for manual clocking operations.
Solution Approach 2:
The hub and cannula are designed with self-aligning features that automatically position the components correctly during assembly without requiring external alignment tools or procedures. The geometry of the mating surfaces provides self-guidance that ensures proper orientation and secure connection.
Data Source
AI summary
Certain embodiments herein disclose a cannula assembly. The cannula assembly comprises a cannula, having a proximal end and a distal end. The cannula comprises a head at the proximal end, the head having one or more wings. The cannula also comprises a hollow rod extending from the head to the distal end. The cannula assembly also comprises a hub couplable to the head and having a housing with an inner wall. The inner wall comprises an undercut, and one or more distal ends of the corresponding one or more wings are configured to fit into the undercut and couple the hub to the head upon insertion of the head into the hub.