Retractable Cannula Assembly for Ophthalmic Surgery
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Solution Overview
Problem
Soft-tipped cannulas used in ophthalmic surgical procedures are insufficiently rigid to effectively open valved cannulas without applying undue pressure, which can lead to buckling or shearing of the tip during insertion, potentially causing trauma to the eye.
Innovation Solution
A retractable cannula assembly with a soft-tipped inner tube that can be retracted into an outer tube for easier insertion through a working cannula, eliminating the need for excessive pressure and preventing tip damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a soft-tipped cannula is used to prevent damage to eye tissue, then tissue safety is improved, but the cannula becomes insufficiently rigid to effectively open the valved cannula without applying undue pressure
Solution Approach 1:
The soft-tipped cannula is nested within a more rigid outer cannula structure. The inner soft-tipped cannula can be advanced through the outer cannula, allowing the rigid outer structure to provide structural support for opening the valved cannula while the soft tip remains protected and ready for safe ocular engagement.
Solution Approach 2:
The cannula system is divided into separate functional segments: a rigid outer cannula portion for structural support and valve opening, and a soft-tipped inner cannula portion for safe tissue interaction. This segmentation allows each component to perform its optimal function without compromise.
2Ease of operation
If pressure is applied to make the soft-tipped cannula rigid enough to open the valved cannula, then ease of insertion is improved, but the soft tip may buckle or become stuck requiring multiple trials
Solution Approach 1:
The nested structure allows the rigid outer cannula to bear the insertion force while the soft-tipped inner cannula passes through passively, eliminating buckling and sticking issues that occur when pressure is applied directly to the soft tip.
Solution Approach 2:
The rigid outer cannula acts as an intermediary structure that transmits insertion forces without causing the soft tip to buckle or stick, mediating between the operator's insertion action and the soft-tipped cannula's passage through the valved cannula.
3Ease of operation
If excessive pressure is applied to insert the soft-tipped cannula, then ease of opening the valved cannula is improved, but the soft tip could be sheared off and fall into the eye
Solution Approach 1:
The soft-tipped cannula is nested within the rigid outer cannula, which absorbs and distributes insertion forces. This prevents excessive localized pressure on the soft tip that could cause shearing, while still enabling effective opening of the valved cannula.
Solution Approach 2:
The rigid outer cannula structure provides beforehand cushioning and protection to the soft tip during insertion, preventing the tip from experiencing damaging forces before it even engages with the valved cannula or eye tissue.
4Productivity
If the cannula tip is extended during insertion, then functionality for fluid aspiration is improved, but the risk of trauma to the eye from the rigid tip is increased
Solution Approach 1:
The cannula system transitions from a static extended tip design to a dynamic configuration where the soft tip can be retracted into the outer cannula during insertion and then extended after safe positioning, allowing the system to adapt its properties based on the operational phase.
Solution Approach 2:
The soft tip is retracted in advance during the insertion phase to prevent trauma, and then extended afterward when the cannula is safely positioned and functional fluid aspiration is required, sequencing the activation of different properties.
Data Source
AI summary
Disclosed herein are surgical instruments used in ophthalmic surgical procedures and associated methods. Particular embodiments relate to a cannula assembly having a cannula tip that is retractable. The cannula assembly may comprise a cannula hub. The cannula assembly may further comprise an outer tube that extends from a distal end the cannula hub. The cannula assembly may further comprise an inner tube that extends from the distal end of the cannula hub and is disposed in the outer tube, wherein the inner tube has a cannula tip that extends from the outer tube and is retractable into the outer tube.