Adjustable Infusion Cannula Depth Control
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Solution Overview
Problem
The existing infusion cannula systems for pars plana vitrectomy lack adjustability, making it difficult to ensure correct placement within the vitreous cavity, particularly in cases with undilated pupils, hazy media, or complex retinal detachments, where standard cannula lengths may be inadequate or too long, potentially causing complications.
Innovation Solution
An adjustable infusion cannula system with a port and internal hub that allows for incremental depth control through a threadable mechanism, enabling the infusion cannula to be inserted to any depth between 3 to 7 mm, facilitated by a trocar and pins for precise placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a standard 4 mm cannula is used, then the device is simple and easy to operate, but it cannot accommodate varying eye sizes and pathological conditions requiring different depths
Solution Approach 1:
The cannula system incorporates an adjustable depth mechanism where the internal hub can be rotated to incrementally adjust the insertion depth of the infusion cannula. This dynamic adjustment capability allows the same device to adapt to different eye sizes and pathological conditions (undilated pupils, hazy media, complex retinal detachments) without requiring multiple fixed-length cannulas, thus resolving the contradiction between adaptability and device complexity.
Solution Approach 2:
The port assembly is divided into separable components: an external cylindrical shell, an internal hub with threads, and the infusion cannula. The internal hub can be independently rotated and adjusted relative to the cylindrical shell, allowing the depth of the infusion cannula to be segmented and adjusted in increments. This segmentation enables precise control over the insertion depth while maintaining a relatively simple overall device structure.
2Reliability
If a longer cannula is used for undilated pupils and hazy media, then correct placement is ensured, but the risk of damaging the natural lens in premature babies increases
Solution Approach 1:
The system allows dynamic adjustment of the cannula insertion depth during the surgical procedure. The surgeon can initially insert the cannula to a safer shorter depth and then gradually extend it to the required depth for undilated pupils or hazy media conditions, thereby ensuring reliable placement while minimizing the risk of lens damage in premature babies. The rotatable internal hub enables incremental depth adjustment with controlled precision.
Solution Approach 2:
The system allows preliminary insertion of the cannula at a safer shorter depth before gradually extending it to the final required depth. This preliminary action enables the surgeon to first establish safe placement and then progressively extend the cannula to achieve the necessary depth for reliable infusion, thereby preventing lens damage while ensuring correct placement.
3Measurement precision
If the infusion cannula is inserted to the desired depth visually, then correct placement is achieved, but the surgeon cannot adjust the depth after insertion in standard systems
Solution Approach 1:
The system incorporates a pointer on the internal hub that aligns with calibration indicia on the cylindrical shell to provide visual feedback about the current insertion depth. This feedback mechanism allows the surgeon to precisely control and verify the depth of the infusion cannula during insertion and adjustment, ensuring accurate placement while making the adjustment process straightforward and intuitive.
Solution Approach 2:
The rotatable internal hub acts as an intermediary mechanism between the surgeon's manual input and the infusion cannula's insertion depth. By rotating the internal hub, the surgeon can precisely adjust the cannula depth in controlled increments, with the pointer and calibration indicia providing real-time feedback. This intermediary mechanism bridges the gap between ease of operation and measurement precision.
Data Source
AI summary
The infusion cannula system for pars plana vitrectomy includes a port (100) mounted over a sclerotomy on the patient's eye (200) and an infusion cannula assembly (400) adapted for connection to a vitrectomy machine that maintains pressure in the eye during the procedure. The port (100) includes an external cylindrical shell (10) that is kept stationary and an internal hub (14) having an insertion tube (17) extending therefrom. The internal hub (14) is threadable into the cylindrical shell (10) in increments to control the depth of penetration of the insertion tube (17) through the sclerotomy incision into the vitreous cavity. The infusion cannula (25) is introduced into the eye (200) through the insertion tube (17) to the desired depth. The internal hub (14) may have a pointer (15) that points to calibration indicia on the cylindrical shell (10) corresponding to the depth of insertion of the infusion cannula (25).