Retina Society 2018: AMD Part I (Including First-Time Presentation of Genentech's Bispecific Anti-VEGF/Ang2 Agent for Neovascular AMD)
The downsizing from 20-gauge (G) to 25G and 23G was a paradigm shift that changed the way we operate. Smaller gauges meant slower flow and flimsier instruments, but the improvements in instrumentation, cut rates, and viewing systems, have made small-gauge vitrectomy the platforms of choice for most VR surgeons to allow efficient, safe, and elegant surgery. Now comes along 27G. The instruments are even flimsier and some of our favorite scissors and pics are not available in this needle-like platform. We were doing just fine with 23- and 25G systems. Is there a role for an even smaller system? We all have different opinions and preferences, but I personally vote yes - I think that 27G systems can play a role in our surgical armamentarium. In a series of posts, I'd like to provide quick overviews of what I think 27G allows. For this first post, we'll go over some of the theoretical benefits of using 27G. There are no robust studies confirming these ideas, so this is based on anecdotal experience. In future posts of this series, I'd like to provide a list of indications where I think 27G is useful, how to overcome some of the perceived limitations, and how 27G vitrectomy can be a great way to train fellows. Superior wound construction The 27G sclerotomies are fantastic. Suturing is almost never required, and the patients are amazed at how comfortable their eyes are after surgery. The image below shows an eye postop week 1 after 27G vitrectomy, and the circle is showing where the sclerotomy is located. Less postop hypotony, less postop bleeding, and great gas fills Because the wounds are so secure, the risk for post-op hypotony is close to zero in my experience, and the gas fill is fantastic for retinal detachment and macular hole surgeries. Since even a momentary decrease in IOP (even when suturing the last sclerotomy at the end of the case) can cause bleeding, especially in diabetic cases. I love using 27G for diabetic vitrectomies, which are prone to postop oozing. One of the most satisfying moments of 27G surgery is the removal of the cannulas (below), when there is often zero leakage. Dissecting into tighter planes The 27G cutter can sneak into tighter surgical planes that we may not be able to with larger gauges. This is especially useful in diabetic dissections. Bimanual dissections with pics, forceps, etc. are my favorite techniques, but with the 27G cutter, I rarely need multiple instruments. That being said, I personally still use larger gauges for the really tight plaques, or employ hybrid 25/27 or 23/27G vitrectomy that we described previously, where we start a case with larger gauge cannulas and use the 27G cutter through the larger valved cannulas. Multi-functional tool As alluded to above, the 27G cutter can function like a Swiss army knife with multiple functions: like a pic by sliding into tighter planes and hooking onto tissues, like forceps by being able to get closer to the retinal surface with aspiration, and like scissors with its precise cutting mechanisms. Thanks for reading and entertaining some of these thoughts. One of the best aspects of VR surgery is that there are so many different approaches to the same problems, and these are just my personal preferences. Please stay tuned for future installations of the 27G series, but next week, we will be providing exciting daily coverage of the ASRS annual meeting in Boston. Yoshihiro Yonekawa, M.D.