Micro Machines

Much like the Borg in Star Trek, resisting the advance of robots into the operating theater is futile. Their superiority is patent. When operated by a surgeon, they have a number of practical advantages: surgeons no longer need to operate at a surgical microscope – or even in the same room as the patient, dramatically improving ergonomics for them. The robots can filter tremor from the surgeon’s hands – adding years to their effective lifespan as a surgeon. They hold the promise of automating parts of procedures, too – like suturing – saving time and speeding workflow, and they can do things no human can do, like hold a needle in place without movement for extended periods (as required with subretinal stem cell delivery), or scale movement to achieve more precision than a human hand ever could. In fact, we recently reported on the first use of a robotic assistant in man, when Robert MacLaren used Preceyes’ R2D2 robot assistant during retinal surgery to help perform an internal limiting membrane peel (1).

Now there’s another robot on the scene: Cambridge Consultants’ Axsis robot (Figure 1), built to assist surgeons in performing cataract surgery. Chris Wagner, roboticist at Cambridge Consultants in the UK hopes Axsis will demonstrate what’s possible in the next generation of surgical robotics.

Here’s what he had to say…

What inspired you to develop the Axsis robot for cataract surgery?

Surgical robots are designed to overcome the complications of surgery through features such as motion scaling, tremor reduction, minimally invasive access and critical structure avoidance through image guidance. We noticed that cataract surgery could benefit from all of these. However, building a robot that can work on the size scale of the lens (<10 mm) is difficult. We took on the technical challenge by asking: “Is there anything stopping us from building a robot on this size scale?” So far, the answer is no. We’ve been able to construct articulating end effectors that are the same size as current cataract surgical tools (1.8 mm) – much smaller than current surgical robot tools.

And does it work?

We’ve been able to show our high performance articulating tool moves at speeds mimicking that of a surgeon’s hands, and we’re showing this can be achieved with a small robot, which is critical for easily integrating the technology into the operating room environment.

What have been the challenges so far?

The biggest was finding the correct combination of materials, manufacturing processes, and assembly techniques to let us build mechanisms at this small size scale – for example, finding an actuation cable approximately the same diameter as a human hair, then threading that cable through holes 150 µm wide in has been difficult. We’ve relied on precision micromachining – along with a healthy dose of steady hands – to assemble this system.

What impact do you think your robot can have?

We’re trying to show the potential for reducing the size of these systems, and our goal is to expand the range of procedures that should be considered candidates for robotic technology. In the case of cataract surgery, although we’re not intending our current system in itself to be a medical device, we’re showing there’s nothing in the physics or mechanism design that limits the introduction of a surgical robot into this procedure. So, one day, we might be able to deliver the precision benefits that laser cataract surgery promises, but without the additional workflow steps.