Abstract
Purpose:
Traditional vitreoretinal surgery is a three-port system with one port dedicated to the infusion, one for illumination, and one for a surgical tool and is largely a uni-manual surgical technique. Currently available illumination devices, which allow for bimanual vitreoretinal provide inadequate illumination. We sought to create an endo-illuminator that provides direct illumination by automatically tracking and directing and internal light source to the surgical field thereby allowing for improved illumination during bimanual surgery.
Methods:
An auto-tracking flexible endo-illuminator was created which was composed of: an image recognition and processing module that tracks the tip of a surgical instrument, an intra-ocular actuation system that bends the flexible end of our proposed endo-illuminator towards the instrument tip, and a holder that secures the rigid end of the endo-illuminator in a fixed orientation during surgery. Actuation of the endo-illuminator was achieved by constructing and endo-illuminator with a flexible distal tip that is embedded with three symmetrically arranged shape memory alloy wire (SMA) loops, which constrict when heated. Instrument tip localization was achieved by using image processing filters to localize the tip based on the video feed from the operating microscope and transmit a signal to redirect the flexible endo-illuminator.
Results:
A 10 time scale-up model of the endo-illuminator was successfully fabricated and tested in saline solution to simulate intraocular conditions. When current was applied to the SMA wires the maximum tip deflection reached 80 degrees with a response time of less than one second. An image recognition and processing algorithm was developed to successfully demonstrate the tracking of an instrument tip. A to-scale holder was fabricated and demonstrated sufficient stability when attached to a dummy head for typical vitreoretinal procedures. The total set-up time for holder assembly was less than one minute.
Conclusions:
We have constructed a novel method of endo-illumination which facilitates bimanual surgery. Because of the high force-to-weight ratio, fast reaction time, large deformation range, ease of manufacture, and low cost, SMA wires provide and ideal actuation solution which can be housed entirely within the eye. Miniaturization to 25-gauge system followed by ex vivo and in vivo testing are necessary to validate this novel robotic endo-illuminator.
Keywords: 762 vitreoretinal surgery