Force-sensing microneedle for assisted retinal vein cannulation

Abstract

Retinal vein cannulation (RVC) is a challenging procedure proposed for drug delivery into the very small retinal veins. The available glass cannulas for this procedure are both hard to visualize and fragile thereby limiting the feasibility of both robot-assisted and manual RVC approaches. In this study, we develop and test a new force-sensing RVC instrument that can be easily integrated with the existing manual and robotic devices. The tool enables (1) the measurement of the forces required for puncturing retinal veins in vivo and (2) an assistive method to inform the operator of the needle piercing the vessel wall. The fiber Bragg grating based sensor can be inserted into the eye through a small (∅ 0.9 mm) opening and provides a quantitative assessment at the tool tip with a resolution smaller than 0.25 mN. Assessment of forces during vessel penetration in the chorioallantoic membranes of chicken embryos have revealed a consistent sharp drop in tool tip force upon vessel puncture that has been used as a signature to provide auditory feedback to the user to stop needle advancement and begin drug delivery.

Robot-assisted retinal vein cannulation with force-based puncture detection: Micron vs. the steady-hand eye robot

“…A detailed performance assessment on Micron trials was reported earlier in [26,27]. In this study, the focus is on evaluation of the SHER system and comparison of its performance with our earlier findings on Micron.…”

“…In our previous work [26], we developed a motorized force-sensing cannulation tool that has a sharp beveled (15°) and bent (45° relative to the tool shaft) microneedle at its tip with an outer diameter of 70 μm (Fig. 1b).…”

“…This makes detecting venous puncture almost imperceptible without the feedback of a proper force-sensor continually monitoring tool-to-tissue interaction forces. To provide such force feedback in retinal microsurgery, our team has developed force-sensing instruments using fiber Bragg grating (FBG) strain sensors [22–26], which have been shown to accurately measure the micro-forces directly at the tool tip without significant degradation due to varying ambient temperature or the forces at the sclerotomy port.…”

Demonstration of Subretinal Injection Using Common-Path Swept Source OCT Guided Microinjector

“…In bench cell biology, accurate injection of foreign materials such as DNA, RNAi, protein, and drug compounds is fundamental to achieve successful expression of desired properties [5][6][7][8][9]. Wang et al developed a computer vision-based microinjection system and successfully performed zebrafish embryo injection with a 99% success rate [5].…”

“…However, the solution does not address the limited visualization of the target through the microscope and additional supportive information is required. An example of relevant additional information may be provided by a force-sensing method [9] to assist retinal microinjection, but it is still not sufficient for precise depth control.…”