Towards vision-based control of a handheld micromanipulator for retinal cannulation in an eyeball phantom

Injecting thrombolytic drugs such as t-PA into tiny retinal vessels thinner than a human hair is a challenging procedure, especially since the vessels lie directly on top of the delicate and easily-damaged retina. Various robotic aids have been proposed with the goal of increasing safety by removing tremor and increasing precision with motion scaling. We have developed a fully handheld micromanipulator, Micron, that has demonstrated reduced tremor when cannulating porcine retinal veins in excised retina, unenclosed by the eyeball. In this paper, we present work toward more realistic handheld robotic cannulation methods using vision-based virtual fixtures to guide the tip of the cannula to the vessel. Using a realistic eyeball phantom, we address sclerotomy constraints, eye movement, and non-planar retina. Preliminary results indicate that a handheld robot aided by visual control is a promising approach to retinal vessel occlusion.