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Engineers in ophthalmology

Today’s technological marvels are products of large-scale collaboration.

Howard Larkin

Posted: Friday, December 7, 2018


Steve Charles accepts the 2018 Charles D Kelman Innovator’s Award from ASCRS Annual Meeting Programme Chair 
Edward J Holland and Anne Kelman
Ridley, Binkhorst, Kelman, Barraquer – the names of the great innovators in ophthalmology are well known and celebrated with, among other things, named lectures at clinical meetings around the world. But without the concerted efforts of thousands of engineers and surgeons, the highly integrated, efficient and ergonomic instruments ophthalmic surgeons rely on today would not be possible, Steve Charles MD told the American Society of Cataract and Refractive Surgery in the 2018 Charles D Kelman Innovators Lecture.
First trained as an electrical and mechanical engineer, from his days as a medical student at Bascom Palmer, Dr Charles always intended to do both microsurgery and engineer better medical technology.
“Techniques don’t work without technology; you can’t do phaco without surgical technologies,” said Dr Charles, of the University of Tennessee and founder of the Charles Retina Institute, Memphis, Tennessee, USA. He emphasised the evolutionary and iterative nature of technology development.
Fame and vanity patents mean nothing on their own, Dr Charles said. “If multiple surgeons and multiple engineers collaborate and we keep the patient and patient outcomes in mind,” however, “then good things happen.”
COMPLEXITY AND TEAMWORK
Very few devices are the invention of a single person, and as complexity goes up, so does the need for large teams in improving technology, Dr Charles said. The first vitrectomy machine was the invention of one man, Jean-Marie Parel for Robert Machemer MD, Dr Charles noted. But modern vitrectomy systems like the Alcon Constellation, for which Dr Charles is the principal architect, are the work of more than 100 engineers.
“[There are] 650,000 lines of code, 14 processors, so you need mechanical, electrical, regulatory compliance, EMI/RFI, all sorts of manufacturing engineering and software engineering,” he said.
The key is that the original machine introduced a workable system of surgery, not just an instrument, and that system has been continuously refined, Dr Charles said. Tracing the evolution of vitrectomy as an example, Dr Charles noted that the next big evolution was invention of the three-port 20-gauge axial system by Conor O’Malley MD and engineer Ralph Heinz. Castigated initially, it was a major step forward, making the procedure more flexible by allowing infusion without the cutter in the eye. It is the basis of systems used today.
Developing lighter, disposable, self-sharpening and dual-action cutters were a series of major innovations that increased cutting speed from about 400 to more than 10,000 per second today. Another critical element is aspiration fluidics, a technology that Dr Charles has helped develop for years. The first Machemer machine used a manual syringe operated by an assistant.
“That’s like driving a car and having your next-door neighbour who had too many beers operate the gas pedal,” Dr Charles said.
This was followed by a rack and pinion syringe drive and then foot pedal-controlled aspiration that gave the surgeon direct control.
More recently, faster processor response time, faster responding, auto-emptying aspiration chambers, foot pedals that allowed aspiration with or without cutting and chambers with multiple control valves and optically controlled fluid levels have made vitrectomy systems ever more stable and responsive, allowing surgeons to focus on the patient, rather than running the machine.
“We went from two- or three-second response times to 100 milliseconds,” he said.
SYSTEM INTEGRATION
Today’s systems are the product of integration, with all functions, including lasers, built into a single device controlled through a single interface, another approach Dr Charles helped pioneer. These now allow the surgeon to do with one piece of equipment what once took a room full of separate boxes run by at least one assistant.
Each advance addressed issues with existing technology, Dr Charles said.
“It isn’t about taking credit or getting your name on it or making money; it is about what was wrong with the last step and how do you go to the next step.”

Steve Charles: scharles@att.net