Semiautomated intraocular laser surgery using handheld instruments

Abstract

Background and Objective-In laser retinal photocoagulation, hundreds of dot-like burns are applied. We introduce a robot-assisted technique to enhance the accuracy and reduce the tedium of the procedure.Materials and Methods-Laser burn locations are overlaid on preoperative retinal images using common patterns such as grids. A stereo camera/monitor setup registers and displays the planned burn locations overlaid on real-time video. Using an active handheld micromanipulator, a 7×7 grid of burns spaced 650 μm apart is applied to both paper slides and porcine retina in vitro using 30 ms laser pulses at 532 nm. Two scenarios were tested: unaided, in which the micromanipulator is inert and the laser fires at a fixed frequency, and aided, in which the micromanipulator actively targets burn locations and the laser fires automatically upon target acquisition. Error is defined as the distance from the center of the observed burn mark to the preoperatively selected target location.Results-An experienced retinal surgeon performed trials with and without robotic assistance, on both paper slides and porcine retina in vitro. In the paper slide experiments at an unaided laser repeat rate of 0.5 Hz, error was 125±62 μm with robotic assistance and 149±76 μm without (p < 0.005), and trial duration was 70±8 s with robotic assistance and 97±7 s without (p < 0.005). At a repeat rate of 1.0 Hz, error was 129±69 μm with robotic assistance and 166±91 μm without (p < 0.005), and trial duration was 26±4 s with robotic assistance and 47±1 s without (p < 0.005). At a repeat rate of 2.0 Hz on porcine retinal tissue, error was 123±69 μm with robotic assistance and 203±104 μm without (p < 0.005).Conclusion-Robotic assistance can increase the accuracy of laser photocoagulation while reducing the duration of the operation.

Conic-Spiraleur: A Miniature Distal Scanner for Confocal Microlaparoscope

“…With manual sweeping, it is difficult to obtain the precision required for an actual tissue scan. An assistive handheld instrument is presented for micropositioning for intraocular laser surgery [13], but it is large to be used in minimally invasive surgery and not intended for a few minutes long manipulation typical for a scan. The motorized surgical microscope presented in [14] enables the surgeon to control the movement of the microscope by index finger movements with a remote controller.…”

Epipolar Geometry for Vision-guided Laser Surgery

“…In (Becker et al, 2010) the authors have developed a semiautomated laser intraocular surgery. Their setup included a laser probe attached to a micromanipulator, a stereo camera working at 30 kHz, a 3D sensor running at 2 kHz and a control system running at 1 kHz.…”

State estimation and feedforward tremor suppression for a handheld micromanipulator with a Kalman filter

“…By actuating these motors, the instrument tip is able to move with respect to the handle in a 2x2x1 mm range of motion to cancel tremor, snap to virtual fixtures [8], apply grids of laser burns [9], or perform other intelligent behaviors [10]. High-rate positioning information is achieved with low-latency optical tracking hardware named ASAP [14].…”

“…While the focus of this paper is not on how to best select the set point, it can be generated by a tremor-compensation filter [7], virtual fixtures [8], or other behaviors [9,10]. Once the set point has been generated by a higher-level control system, the low-level control system attempts to track the set point with the tip of instrument.…”