An opening closer to the tip. A firmer instrument. Better fluidics. A larger shaft. Every vitreoretinal surgeon knows what I am talking about. In case you’ve been under a rock for the last 6 months, of course you would know by now that Alcon Surgical has finally launched their much anticipated 23-gauge pars plana vitrectomy system to add to their posterior segment surgical arsenal on the Accurus system.
Long the workhouse of the nearly 10 year-old Accurus system, 20-gauge (standard) vitrectomy has been supplanted by the small gauge 25-gauge instrumentation over the last few years. Vitreoretinal surgeons were initially hesitant to adopt to the 25-gauge vitrectomy platform until they witnessed the smiles on their patient’s faces on post-op day number one (POD#1). Some patients undergoing 25-gauge vitrectomy for repair of epiretinal membranes (ERMs) or macular holes (MHs) barely looked like they underwent any eye surgery. Despite a significantly reduced internal diameter of the vitrectomy probe, simple posterior segment cases like ERMs, MHs, or straightforward vitreous hemorrhage cases could be carried out with minimal additional vitrectomy time. As an added bonus, no sutures were needed to place the infusion line or to close the self-sealing sclerotomy wounds at the end of the case. So, while some time may be lost due to slower vitrectomy times, the time saved by not closing sclera and conjunctiva are a plus. In addition, the re-introduction of trocars made passing instruments more facile. In my experience and that of others, patients truly do “recover” from the surgical intervention much faster compared with 20-gauge vitrectomy.
So, what’s not to like about 25-gauge vitrectomy? Plenty. For one, many of the so-called self-sealing sclera wounds were not entirely closed at the end of the case and a not insignificant number of patients either required scleral sutures at the end of the case of came in on POD#1 with hypotony, conjunctival bleb, and/or choroidal effusions. Theoretically the patency of these wounds could lead to ingress of periocular fluids into the eye and result in infectious endophthalmitis. In reality, several reports of this have indeed come to light from various centers, but this has not been the rule. Initially, lack of 25-gauge instrumentation was a problem, but this problem has been largely solved.
Of course, 25-gauge vitrectomy is not appropriate for all posterior segment cases. For example, I believe the instruments are too flexible for a safe vitrectomy with intraocular lens exchange and a difficult diabetic traction retinal detachment repair. Even for simple MH or ERM cases, it can be agonizingly difficult to get the hyaloid up. I know many people who like to use 25-gauge for primary vitrectomy for repair of retinal detachment, but I am not one of them.
One of the most common complaints about 25-gauge vitrectomy products are their extreme flexibility. It is difficult to rotate the eye in the X-Y axis and to rotate the instruments anteroposteriorly without causing the instruments to bend severely. Advocates claim that all you have to do is “choke up” on the instruments to help with this problem, but I find this to be a rather inelegant solution to a real problem. This type of advice places the problem-solving burden on the surgeon instead of on the manufacturer, where the onus really lies.
Having said all of this, I personally love the 25-gauge vitrectomy system from Alcon. I am willing to put up with all these shortcomings for the sake of a smoother surgery with a happier patient in the postoperative period. That’s what I used to think…until I had the opportunity to get several 23-gauge vitrectomy (Alcon) cases under my belt.
As your Alcon Surgical rep can echo, there are several advantages to the new 23-gauge system. The larger bore vitrectomy needle allows for faster vitreous removal and increased vacuum power to better engage the posterior hyaloid or vitreoretinal membranes. In addition, the vitrectomy aperture is 50% closer to the tip, which allows for easier surface dissection with the vitrectomy handpiece. Faster cut rates (up to 2500 cuts per minute) also allow for safer and meticulous shaving of the peripheral retina near the vitreous base or even posteriorly.
Initially, I did not like the new 23-gauge trocars, but I have come to love them. They seem to be sharper than the 25-gauge trocars, but I am told both are equally sharp. The trocars are preloaded so the technician does not have to “eye the needle” in the OR, but still has to make sure not to turn them upside down when passing them off to the surgeon or else the trocar will fall off the sharp. The latest iteration of these trocars have marked bevels that inform the surgeon when it’s time to redirect the instruments after the initial tangential sclera approach. Although a true “shelved incision” is not the result of this maneuver, the “angled incisional approach” does provide a significant degree of wound self-closure. The trocar insertion maneuver does leave them looking cock-eyed after insertion, but this aesthetic departure aside, I have found them to be less prone to dislocate spontaneously than the 25-gauge trocars. These new trocars are also metallic and have a firmer feel than their plastic 25-gauge counterparts (kind of like the door closing on a BMW).
Because the trocars are larger and the incisional approach is more complex, one drawback of the new system is that the patients actually look like they underwent eye surgery when you see them on POD#1. In addition, at a posterior infusion rate of 40 mmHg, you frequently will have a geyser effect through one of your trocars when it is not plugged with an instrument. This can be annoying if it gets the back of your BIOM lens wet. Speaking of plugs, the plugs for the 23-gauge trocars are annoyingly difficult to place even under moderate infusion pressures.
It is much easier to pass instruments through these trocars, although instrument choice is limited to end-grasping forceps, ILM forceps, a curved scissor, a soft-tipped extrusion cannula, a fluted soft-tipped extrusion cannula, and an endolaser probe. Outside of Alcon Surgical, additional instrumentation for their 23-gauge system like a Tano Diamond Dusted Membrane Scraper is available from other vendors.
I also feel that the 23-gauge vitrectomy system has expanded the spectrum of cases that I am willing to do via a small gauge vitrectomy approach. I am much more willing to do a primary or secondary repair of a retinal detachment with 23-gauge vitrectomy—in fact, I prefer it to 20-gauge instrumentation because of easier tissue manipulation with the aperture closer to the tip. In addition, I would not hesitate to use 23-gauge instrumentation for an IOL exchange or in cases with anterior pathology. The new instruments are stiff enough to allow for peripheral manipulation without pathologic bending.
So, if you ask me, size does matter and Alcon has stepped up to the plate to solve the shortcomings associated with 25-gauge vitrectomy. I still will do a few macular hole or ERM cases with the 25-gauge system, especially if I want the outside of the eye to look “as pretty” as the inside does on POD#1, but mainly I’ll do it for old time’s sake.
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