VR surgery innovations

The tradition of innovation in vitreoretinal surgery which began with Robert Machemer MD is continuing, according to David Steel MD. Speaking at the 16th EURETINA Congress in Copenhagen, Denmark, he told colleagues about three innovations they should be using now and three that are on the horizon. “These are exciting times with a lot to look forward to,” said Dr Steel, a consultant at Sunderland Eye Infirmary, UK. He listed transconjunctival narrow-gauge vitrectomy, the highest available cut rate when removing vitreous, and tissue specific stains for epiretinal membrane (ERM) and internal limiting membrane (ILM) peels as the things vitreoretinal surgeons should be using now. The advantages of transconjunctival narrow-gauge vitrectomy include reduced entry site breaks and trauma. Most importantly, however, smaller gauge instrumentation brings greater precision with reduced likelihood of damaging collateral tissues, said Dr Steel. The reason for using the highest possible cut rate is that it enables safe attainment of an acceptable flow rate when operating with narrower-gauge instrumentation. Dr Steel explained that achieving a surgically acceptable flow rate through a narrower tube is not just an engineering challenge, but fundamentally a law of physics problem. Although flow rate can be increased by increasing vacuum (itself limited by atmospheric pressure), use of higher vacuum at a set flow and cut rate leads to higher vitreous acceleration and more traction on the retina. “Using a high cut rate partly ameliorates that problem. And because traction continues to decrease as cut rate increases well beyond current speeds, we need to be cutting faster than we are currently,” said Dr Steel. However with mechanical guillotine cutter systems, higher cut rates are associated with increased resistance to flow because of reduced port open time. Dual pneumatic drives partially addressed that problem for cut rates that are currently used, but now, dual action cutters are allowing even higher cut rates with reduced hydraulic resistance, higher achievable flow and lower vacuum. By enhancing visualisation, the use of ERM/ILM-specific stains allows for more complete membrane removal and for faster surgery that reduces retina exposure to toxic light.

Because traction continues to decrease as cut rate increases well beyond current speeds, we need to be cutting faster than we are currently

FUTURE ADVANCES Dr Steel named stereoscopic heads-up surgery, intraoperative optical coherence tomography (OCT), and modalities that will eliminate the need for tamponade as three things that will be ready for mass adoption with some additional ‘tweaking’. Heads-up surgery has an obvious benefit of improving surgeon ergonomics, but Dr Steel said its main advantages relate to enhanced visualisation and intelligent application opportunities. Intra-op OCT will also bring a new dimension to visualisation by providing surgeons with a ‘street view’. David Steel: david.steel@ncl.ac.uk