Abstract:
Retinal surgery procedures like epiretinal membrane peeling and retinal vein cannulation require surgeons to manipulate very delicate structures in the eye with little room for error. Many robotic surgery systems have been developed to help surgeons and enforce safeguards during these demanding procedures. One essential piece of information that is required to create and enforce such safeguards is the distance of the surgical tooltip from the retinal surface. For example, this knowledge can help us implement virtual fixtures that prevent the tool from penetrating beyond a certain predetermined limit below the surface. However, estimating the position of the retinal surface is a hard problem due to the lack of features in microscope imagery and a complex light path.

In this talk, we propose to use the area of a laser aiming beam attached to the surgical tool to determine the distance of the tool from the retina. We first map the laser area to the tool height at a few selected angles. We then fit a simple polynomial function to this data and combine it with a Kalman filter to determine the laser height as a function of the tool angle and the laser area. Using this simple method, we then predict the height of the tool from the surface at random angles and magnifications with an accuracy of tens of microns. We also demonstrate the effectiveness of this method by predicting retinal touches during freehand motion.

Committee:
Dr. Cameron Riviere, Chair
Dr. John Galeotti
Dr. Zeynep Temel
Shohin Mukherjee