The field of medical robotics seeks to pair physician and machine in order to achieve more than either can alone. That mission inspires Wilmer ophthalmologist Peter Gehlbach, M.D., Ph.D., who, for the past decade, has been working with Russell Taylor, Ph.D., considered the father of medical robotics, and Iulian Iordachita, Ph.D. Taylor is the John C. Malone Professor and Iordachita is an associate professor of engineering, both at the Johns Hopkins Whiting School of Engineering.

During surgery on the retina—classified as “microsurgery”—the forces are so small that a human cannot feel them. “The entire surgical procedure is performed using only information that can be seen,” says Gehlbach. Because of this, one project between Wilmer and Whiting has focused on creating the sensation of “touch” for the surgeon during a microsurgical procedure through a technique known as sensory substitution.

“We have equipped tools with force sensors able to detect exceedingly small forces. The information acquired by these sensors is relayed to a computer, which sends the interpreted information to an actuator,” says Gehlbach. “An example of such an actuator in this case is a device that produces a sound—a soft tone for a soft force and a louder tone for a larger force. So even though we still can’t feel these tiny forces, we can now hear them and use that information.” The result is that one sense—hearing—is substituted for another—touch—to communicate previously undetectable, but very useful information.

Today retinal surgeons perform eye surgery with “a high level of success and excellent levels of safety,” and at a “reasonable cost,” says Gehlbach. “So, what is the potential value of what we are doing robotically?” he asks.

Gehlbach notes that as gene therapy, nanomedicine and stem cell transplantation surgery develop into a reality, they will demand a highly precise means by which to deliver the fragile materials involved in these treatments, which robotic surgical tools could provide. Robotic surgery also could aid the cannulation of tiny retinal structures, which involves inserting a thin tube into a vein to draw blood or administer medication, says Gehlbach. Other applications could include the automation of surgical maneuvers that humans cannot perform and employing tissue-imaging devices humans currently cannot use because of hand tremors.

“We are at the very limit of what humans can do based on their ability to see and resolve targets, to sense forces and to control their normal human tremor,” says Gehlbach. “However, we are only at the very beginning of what a machine can do. The exciting question that remains is, where can the machines we build take microsurgery?”