There are many ways to effectively address complex vitreoretinal surgical pathology. In this article I present my preferred devices for treating a diabetic traction retinal detachment (TRD). I am a consultant for a number of device manufacturers and am partial to devices that I have had a hand in developing. There may be excellent alternatives to the devices and techniques I describe below; of that I am certain. This article is simply a description of the way I currently choose to operate in these cases.

The battle plan for surgery begins in the office. Most diabetic TRDs are amenable to repair with 25-gauge instrumentation, which is my preferred approach. However, if there is a high probability that a lensectomy will be necessary (a rare event), or if there are unusually thick membranes that cannot be readily severed with a 25-gauge vitreous cutter, I will plan to use 20-gauge instruments.

20-GAUGE CASES
I perform most 20-gauge cases with the One-Step sutureless cannula system from Synergetics (O'Fallon, MO). The trocar of this system has a “razor-edge” blade (Figure 1) that creates a linear incision as the trocar-cannula unit is inserted. The preloaded cannula is made of the same polyamide material used in most 25-gauge trocar- cannula systems, and it deforms just enough to allow the trocar to be withdrawn after insertion. This creates a snug fit for the cannula. If the wound is properly constructed (with a flat angle of entry while the sclera is “flattened”), it is reliably watertight at the conclusion of the case (Figure 2).

A fragmatome can be used through these cannulas, as can most 20-gauge instruments. Large curved scissors will not fit through the cannulas, however. If I need large horizontal scissors, I simply remove one of the cannulas. In most cases the wound remains self-sealing even if this is done.

25-GAUGE CASES
As mentioned above, I prefer a 25-gauge approach for most diabetic TRDs. The newer 25-gauge high-speed pneumatic cutters remove blood and vitreous with excellent flow. The smaller diameter of the cutter makes it an excellent tool for membrane dissection and delamination, and the smaller cannulas minimize fluid loss and pressure fluctuations during instrument exchanges.

I always use chandelier illumination for complex diabetic cases. The diffuse illumination of the chandelier provides an important overview of the pathology during the vitrectomy and allows me to be more aggressive while stripping the posterior hyaloid. I am often able to safely strip large areas of fibrovascular tissue along with the hyaloid. Diffuse illumination allows me to more thoroughly identify areas of remote traction during this maneuver, thereby reducing the chance of creating an iatrogenic retinal break.

Regardless of the type of chandelier used, it is important that the fiber be aimed posteriorly. Autoclavable metal vascular clips are an excellent way to secure the fiber in the desired direction (Figure 4).

One of the major advantages of chandelier illumination is the improved ability it provides to perform bimanual dissection. I typically use a serrated pick together with the 25-gauge vitreous cutter to attack broad sheets of fibrovascular tissue (Figure 5). The pick allows me to provide counter-traction and to more easily introduce the cutter into tight spaces. Other combinations include pick-forceps or forceps-scissors. The chandelier allows me to use my favorite instruments, not just illuminated ones.

Chandelier illumination also allows me to perform my own scleral depression. I simply plug one cannula and use my free hand to manipulate and depress the globe. I find this to be quicker and safer for removing peripheral vitreous and blood than scleral depression performed by a surgical assistant. In phakic eyes I temporarily move the infusion line to one of the superior cannulas to allow access to the inferior periphery with less risk to the crystalline lens.

One disadvantage of chandelier illumination, compared with a conventional light pipe, is a diminished ability to see clear vitreous or to distinguish transparent epiretinal membranes. These are not relevant challenges in most diabetic vitrectomies, but I occasionally open a conventional light pipe to better identify the internal limiting membrane, which I typically peel from the macula if there is obvious macular distortion or edema.

With the advent of preoperative off-label injection of vascular endothelial growth factor inhibitors, uncontrolled bleeding has become much less an issue. However, bleeding is much more easily managed with chandelier illumination, which allows me to use the cutter or an extrusion needle in one hand and an autoclavable intraocular cautery (Bausch + Lomb, Rochester, NY) in the other. This is a less expensive and more effective way of controlling bleeding than using a disposable aspirating bipolar cautery.

LASER
After the membranes are stripped and bleeding is controlled, it is usually time for laser application. I typically use a 25-gauge Synergetics Directional Laser Probe, which utilizes a curved “memory metal” fiberoptic sleeve within a straight metal outer sleeve. When the curved sleeve is constrained within the outer sleeve, the straight probe can be inserted through the 25-gauge cannula. When the outer sleeve is withdrawn or the inner sleeve is advanced (both actuating mechanisms are available), the tip of the probe can be curved more than 90°. This allows thorough laser treatment of the peripheral retina even in phakic eyes. There is also an illuminated version of the directional laser probe, which can be used as a conventional light pipe as well as an illuminated laser probe.

In some cases, breaks in the retina (whether pre-existing or iatrogenic) necessitate fluid-air exchange prior to laser treatment. The glare of the 25-gauge chandelier can be quite bothersome in an air-filled eye, particularly when one is trying to laser in the region of the chandelier. I sometimes find it necessary to temporarily dim the illumination of the chandelier. This is a situation in which the One-Step chandelier can be truly helpful. The outer 25-gauge needle can be advanced to partially shield the 27-gauge fiber. This virtually eliminates glare while still providing useful diffuse illumination. Having said that, I still prefer the larger fiber of the 25-gauge chandelier; the real challenge is in the membrane dissection, not in the laser treatment, and I prefer to have more light.

FINAL THOUGHTS
Finally, a disclaimer. I have described the way I address most diabetic TRDs, but for the true “nightmare” cases I typically operate with 20-gauge instruments, without cannulas. All cannulas, in any gauge, will not occasionally pull out of the eye at an inopportune time, and the desire to avoid sutures is insignificant in the face of truly challenging surgical pathology.

In such cases, I create small conjunctival peritomies. I use a 25-gauge chandelier or a sewn-in 20-gauge illuminated infusion line. I make flattened sclerotomies, parallel to the corneal limbus, with a microvitreoretinal blade–the same wound architecture as with the 20-gauge One-Step cannulas. The longer sclerotomies act as natural valves and usually eliminate the need for scleral plugs.

Carl C. Awh, MD, practices at Tennessee Retina in Nashville, TN. Dr. Awh states that he is a paid consultant to Synergetics, and a paid consultant to Bausch + Lomb. He may be reached at +1 615 983 6000; e-mail: cawh@aol.com.