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Innovation in retina surgery

Technological innovation is crucial to the continued improvement 
of vitreoretinal surgery.

Leigh Spielberg

Posted: Thursday, March 1, 2018

Technological innovation is crucial to the continued improvement of vitreoretinal surgery. This was abundantly apparent during the RetinaTech Bio-Engineering Session during the 17th EURETINA Congress in Barcelona, Spain.

Subtitled “Where Surgery Meets Technology”, it featured a group of 12 highly experienced vitreoretinal surgeons who have dedicated their careers to developing the current and future equipment that we now have or can look forward to in the future.

The session covered a wide range of topics, including 3D visualisation, ultrasonic vitrectomy, IOP control, robotics, informatics and a new type of retinal prosthesis, among others.

A new concept that has garnered a great deal of attention during the past few years is 3D visualisation for vitreoretinal surgery. This provides a remarkable combination of both increased magnification and increased depth of field as compared to viewing through the oculars of a microscope.

Steve Charles MD, Charles Retina Institute, Tennessee, USA, is a great proponent of 3D surgery, but he baulks at the term “heads-up surgery”, which he finds a misleading concept.

“There is no ergonomic benefit,” he says, as operating microscopes have had tilt oculars for decades. Instead, advantages can be found in the much lower endoilluminator levels required, which can be set at an astonishingly low 1-5% for macular surgery. This decrease has been made possible in part by the recent switch to OLED screens and high sensitivity CMOS camera pair.

Pravin U Dugel MD, Managing Partner, Retinal Consultants of Arizona, Phoenix, Arizona and Clinical Professor, University of Southern California, Los Angeles, USA, has also focused on using advanced technology to improve visualisation during vitrectomy.

“Once you digitalise images, you can do anything you want with them,” Dr Dugel, referring to the head-mounted displays used by fighter pilots, which provide information like flight data and video supplied by external cameras.

Three primary concepts are guidance, overlay and enhancement. Guidance refers to digital indicators of an instrument’s intraocular location, helping to avoid inadvertent lens or retina touch. Overlay “makes the preoperative intraoperative”, overlaying preoperative images such as fluorescein angiography over the intraoperative retinal image. Enhancement permits reduced illumination and allows the surgeon to see otherwise invisible features such as the fine details of an epiretinal membrane.

Kirk Packo MD, Rush University, Chicago, USA, continued this line of thought. The combination of dual 3D high-dynamic-range cameras, a high-speed digital graphics processor and a 4K ultra HD OLED display with rapid refresh has the potential to transform the way we see the retina during surgery. Colour tone mapping, by increasing the green channel of the display, can vastly enhance the effect of ICG colouring of the ILM, possibly allowing a lower ICG concentration. Dr Packo showed how red-free images could enhance the visualisation of membranes. Packo added that while these are all available now, it is the future of digital 3D imaging that holds even more excitement. Using the digital domain to visualise what is invisible optically opens up technologies such as overlay fluorescent microscopy, infrared imaging and fluorescent colour tagging of tissues, to name just a few.

A new prototype of a hypersonic vitrector was introduced by Prof Paulo Stanga MD, Manchester Royal Eye Hospital, England. A hypersonic vitrector needle tip’s up-and-down motion at 1.5 million times per minute creates an active zone in front of the needle’s port that “liquefies” the vitreous. This modifies the viscosity of the vitreous before it passes through the port.

“Hypersonic vitrectomy breaks up the collagen fibres so small that it’s almost like blending,” said Dr Stanga.

Further, the vitrector’s port is very close to the tip, which is ideal for aspirating preretinal haemorrhage or initiating a PVD. He reported the results of the first ever study in humans, which was designed to analyse its effectiveness and safety.

Dr Stanga said that he “would consider this an additional tool, and not yet a replacement technology for the current standard guillotine model. This new technology allows for the fabrication of small-gauge hypersonic vitrectors with the efficiency of larger guillotine ones and also offers the potential for the removal of vitreous, silicon oil and soft lens matter, as well as the execution of retinectomies, all using the same needle.”

Tommaso Rossi MD, San Martino Hospital, Genoa, Italy, discussed IOP control systems during vitrectomy. He told delegates that IOP estimation by the vitrectomy machine is of paramount importance in keeping the optic nerve and retina safe and sound and that significant improvements can be made to existing devices. Particularly, IOP spikes due to instantaneous surgical manoeuvres cannot be corrected by feedback mechanisms nor prevented by feed-forward controls, but passive mechanisms such as valve may cut them, he noted.

Carl Awh MD, Tennessee Retina, USA, presented delegates with devices from Katalyst Surgical that use newer manufacturing techniques to lower costs while maintaining, or improving, quality. He showed a vitreoretinal forceps tip in which the internal drive mechanism is manufactured with a 3D printer. This allows more rapid prototyping and modification, more complex internal geometries and substantial cost savings, said Dr Awh. A new endolaser probe utilises a reusable connector and handpiece, available with curved, flexible, or steerable tips, but with disposable, universal gauge optical fibres.

Marc de Smet MD, MIOS, Lausanne, Switzerland, discussed Preceyes, the ophthalmic robotics company of which he is Chief Medical Officer.

“We’re certainly not the first to approach the concept of vitreoretinal robotics, but we were the first to get into the eye,” he commented.

He described the four different robotic concepts in eye surgery: the handheld tool, instrument co-manipulation, instrument telemanipulation and magnetic control. Each varies in the degree to which the robot can filter tremors, scale motion and allow automation. With telemanipulation, the intended goal is to use robotics to enhance existing procedures currently performed, and to allow surgeons to execute manoeuvres not possible with currently available technology.

Steve Charles: scharles@att.net
Pravin Dugel: pdugel@gmail.com
Kirk Packo: kirk_packo@rush.edu
Paulo Stanga: 
p.stanga@retinaspecialist.co.uk
Tommaso Rossi: tommaso.rossi@usa.net
Carl Awh: carlawh@gmail.com
Marc de Smet: mddesmet1@mac.com