Beginning to See the Light
Beginning to See the Light
Endoillumination is now an option in surgery.
Carl C. Awh, MD
The development of modern chandelier illumination for vitreoretinal surgery is a beautiful example of the old saying, "Necessity is the mother of invention."
When 25-gauge vitrectomy was introduced almost a decade ago, the lack of sufficient illumination through a 25-g lightpipe was a significant limitation. The standard light sources of that time were adequate for 20-gauge fibers, but were insufficiently bright enough to deliver much light to the end of a 25-g probe. The appeal of 25-g vitrectomy was obvious to many, and this excitement drove the development of far more powerful light sources, such as the Synergetics (O'Fallon, MO) Photon, one of the first of a new generation of high-output xenon light sources that could deliver a tremendous amount of light through 25-g fiber optic probes.
These brighter light sources made an old idea, that of chandelier illumination, practical. Devices for diffuse scleral-fixated endoillumination were commercially available many years before the advent of 25-g vitrectomy. However, these devices (such as the first-generation MIS, or multi-port illumination system) never gained widespread acceptance because of inadequate illumination, a cumbersome number of necessary fiberoptic cables, or both.
Flash forward to 2010: High-output light sources using xenon, mercury-vapor, or mercury-xenon light sources now allow surgeons to use not only brilliant 25-g lightpipes, but a host of illuminated accessories that enhance our ability to perform effective surgery in all gauges. In this article, I will discuss the indications, devices, and techniques I employ when using chandelier illumination during vitreoretinal surgery. I am a consultant for a number of device manufacturers and am naturally partial to devices that I have had a hand in developing. There are excellent alternatives to the devices and techniques I am about to describe and my intention is not to promote one manufacturer over another, but simply to describe how I use the technology.
First, let's define what I mean by "chandelier" illumination. By this, I refer to a source of diffuse endoillumination separate from a lightpipe held in the surgeon's hand. The chandelier can be a transconjunctival or scleral-sutured device secured in its own sclerotomy or cannula. It can also be an optical fiber that enters the eye through the infusion line.
Although diffuse illumination can be useful in almost every case, a chandelier typically adds cost to the case, and there are many cases for which I don't use one. A handheld diffusion lightpipe provides excellent illumination for simple diabetic hemorrhages, particularly for those eyes that have already had extensive laser photo-coagulation and where scleral depression and peripheral dissection are not anticipated.
The reflections and changes in contrast provided by a focal lightpipe are more useful to me than the diffuse light of a chandelier while peeling the internal limiting membrane or epiretinal membrane from the macula. Therefore, I typically use only a standard focal lightpipe for macular surgery.
It is easy to see specks of dust floating through a sunbeam in an otherwise darkened room. Similarly, clear vitreous is easier to see with focal illumination than with chandelier illumination. Hemorrhage-filled vitreous is easy to see with chandelier illumination, and some surgeons inject triamcinolone or other dyes into the vitreous to make it easier to detect using only diffuse illumination. In cases where I plan to use a chandelier, I typically still use the focal lightpipe provided in the vitrectomy pack to speed the core vitrectomy.
The cases in which I typically use chandelier illumination are those in which I can anticipate the need to perform any of the following intraoperative maneuvers:
• Scleral depression for vitreous dissection, endolaser, or peripheral/anterior membrane peeling.
• Complex membrane dissection.
• Repair of traction retinal detachment.
• Pars plana lensectomy.
• Intraocular foreign body removal, including removal of retained lens material.
The common feature of each of these cases is my preference to operate bimanually, without the need for an illuminated instrument such as an illuminated pick. Using either a contact (my preference) or noncontact widefield viewing system, a chandelier allows me to perform my own scleral depression during vitrectomy, subretinal fluid drainage, or endolaser. Although I have excellent surgical assistants, I have better control over the eye when performing my own scleral depression. This is particularly important when I am removing vitreous next to mobile or atrophic peripheral retina.
I was trained as a fellow to operate bimanually, usually with automated scissors (the MPC) together with an illuminated tissue manipulator or lighted pick. Now, with a chandelier and the current generation of high-speed, small-diameter vitreous cutters, I find the combination of a serrated pick and the vitreous cutter sufficient to tackle all but the most difficult membrane dissections. For thick and tenacious membrane dissections, I often use a pick or forceps in one hand to provide countertraction while grasping and stripping membranes with forceps in the other. The countertraction provides significant protection against retinal breaks. The ability to use whatever forceps, pick or scissors I prefer is a distinct advantage over using a disposable illuminated instrument.
Chandelier illumination allows me to understand better the remote effects of my actions during surgery. For instance, during vitrectomy for diabetic traction retinal detachment, the diffuse illumination of the entire retinal surface helps me recognize areas of tightly adherent vitreous and taut retina. This awareness can prevent iatrogenic retinal breaks during what might seem to be the easiest part of the case — the initial core vitrectomy. Understanding the overall relationship between the vitreous and the detached retina allows me to identify the best places to attack the pathology, and attention to the movement of the retina allows me to decrease traction or vacuum just enough to prevent a retinal break.
A chandelier is useful for pars plana lensectomy for two reasons. First, the transillumination of the lens makes it easier to see the location of the fragmatome relative to the lens capsule. Second, it's not uncommon for me to lose a fragment or two of the lens during pars plana lensectomy (see below). Although I don't perform combined phacoemulsification and vitrectomy like many of my colleagues, I would guess that transillumination of the lens would also be helpful during conventional cataract surgery.
Finally, during removal of foreign bodies (including dropped lens nucleus, dislocated intraocular lenses, and IOFB due to penetrating trauma) it is useful to have two working instruments in the eye. For dislocated nuclei, I will sometimes impale the nucleus with a pick and then use the cutter or fragmatome to "eat the lollipop." A second forceps is tremendously helpful for manipulating a dropped IOL or other graspable foreign body.
There are a variety of chandelier options now available. For cases in which I anticipate a need to dissect bimanually, I typically use the Synergetics 25-g "Awh Chandelier," coupled to the Photon II light source or, more recently, to the new Bausch+Lomb (Rochester, NY) StellarisPC, which has dual xenon and mercury-xenon light sources and which accepts third-party illuminated disposables. I prefer this device because it has the largest optical fiber of the chandeliers available to me (25-g) and, therefore, provides the brightest diffuse illumination. It's useful to mention that macular phototoxicity risk from chandelier illumination is virtually nonexistent due to the relatively large distance from the fiber tip to the macula and to the diffuse illumination pattern.
Although the 25-g Awh Chandelier provides great illumination, it has a few imperfections. For instance, it is designed to be inserted through a transconjuctival 25-g needle puncture and this can be challenging. Also, it cannot be moved from one location to another during surgery. The bare optical fiber creates uncomfortable glare in an air-filled eye.
In previously unoperated eyes, I always insert the 25-g chandelier before inserting cannulas or an infusion line. The vitreous-filled eye is firm enough to maintain its pressure and shape during chandelier insertion. If the eye has had a prior vitrectomy, I will insert one cannula and attach the infusion line before inserting the chandelier. Otherwise, the 25-g needle puncture can lead to rapid "deflation" of the eye before the chandelier is even inserted. I know from experience and from the comments of colleagues that this chandelier can be tricky to insert. I've developed an effective technique, which I will describe next in some detail. Although the number of steps may seem daunting, the entire process takes only around 30 seconds.
Here are my steps for inserting the 25-g Awh Chandelier (for this example, I describe my technique for a patient's right eye):
1. Grasp the chandelier neck with a heavy blunt forceps, positioned for the left hand (for right eyes, I insert the chandelier in the inferonasal quadrant with my left hand). My assistant takes the forceps from me and holds it in a manner that will allow her to hand it to me without losing grasp of the chandelier. The light should be turned off until after the chandelier is inserted.
2. Rotate the eye upward and outward by pressing a cotton-tipped applicator into the superior fornix. Friction will hold this in place (Figure 1).
Figure 1. Use a cotton-tipped applicator to rotate the eye outward.
3. Using the right hand, press down on the conjunctiva with the Horseshoe Scleral Marker (Synergetics) an instrument I designed specifically for this application. Marks on the surface of the horseshoe-shaped plate indicate distance from the limbus (Figure 2).
Figure 2. The marks on the surface of this horseshoe-shaped plate indicate distance from the limbus.
4. Keeping the horseshoe marker in place, create a 25-g transconjunctival puncture with the left hand. Remove the needle from the eye, but do not look away from the puncture wound!
5. Keeping the puncture wound in sight while applying gentle pressure with the horseshoe marker to prevent the conjunctiva from ballooning, take the blunt forceps (in which the chandelier is already grasped) from the assistant.
6. Without looking away from the puncture site, insert the conical tip of the chandelier through the conjunctival opening and seat it in the barely visible scleral wound (Figure 3).
Figure 3. The tip of the chandelier is now seated in the scleral wound.
7. Before fully inserting the chandelier, withdraw the horseshoe marker. The open end of the "horseshoe" allows the marker to be withdrawn without moving the chandelier.
8. Hand off the horseshoe marker and grasp the cotton-tip applicator with the right hand. Apply gentle pressure to stabilize the eye with the right hand, and with the left hand, press the chandelier firmly toward the center of the eye. The chandelier will pop into place (Figure 4).
Figure 4. The chandelier is now in place.
9. Adjust the chandelier fiber so it points toward the center of the eye. I prefer to use an autoclavable metal vascular clip to secure the fiber to the surgical drape (Figure 5 — the Awh Chandelier in position).
Figure 5. The Awh chandelier in position.
Several years ago, in an attempt to simplify the insertion process, we developed a "One-Step" Chandelier. This device incorporates a 27-g optical fiber within a retractable 25-g needle sheath. To insert the One-Step chandelier, the needle is advanced to cover the optical fiber. The needle is then inserted transconjunctivally, in the same way that 25-g transconjunctival cannulas are placed. After insertion, the needle sheath is withdrawn to expose the fiber tip.
This chandelier is not only easier to insert, but the ability to variably expose the fiber allows dramatic reduction of glare in an air-filled eye while maintaining a useful amount of illumination. The only reason I don't use this device more often is that the smaller 27-g optical fiber provides a bit less light than the original 25-g chandelier. This is not an issue for simpler cases, such as primary retinal detachment repair, but I prefer the maximum amount of light for more complicated cases. Dr. Yusuke Oshima has developed 27-g version of this chandelier (Figure 6), which contains 29-gauge fiber!
Figure 6. A 27-gauge version of the chandelier (A) is also available, including a 29-gauge fiber (B).
Another option for diffuse light is an illuminated infusion line. These devices, in which an optical fiber runs parallel to and finally enters the lumen of the infusion line, are available from Synergetics in 25-, 23-, and 20-gauge. The 25- and 23-g illuminated infusion lines require a special transconjunctival cannula (a component of the device), because the silicone infusion line has to be placed over the cannula in order to provide a large enough inner diameter for the optical fiber without limiting infusion flow. The 20-g illuminated infusion line comes in two versions: one, which looks like a conventional sew-in infusion line, and a second, which works with the 20-g "one-step" sutureless cannula system. Illuminated infusion lines eliminate some of the clutter of the separate entry wound and fiberoptic cable of independent chandeliers. The fibers are somewhat shielded by the infusion cannula, so glare is less in an air-filled eye. However, the optical fibers are small diameter and provide less illumination than the 25-g chandelier.
As I mentioned earlier, excellent alternatives are available from other manufacturers. The Tornambe Torpedo (Insight Instruments, Stuart, FL) is a 25-g single-fiber chandelier compatible with multiple light sources. Dutch Ophthalmic (Exeter, NH) produces both a single-fiber chandelier and a "Twinlight" device that requires inserting two separate fibers, but which may provide more uniform spread of illumination.
Improvements in chandelier and light source design have made hands-free diffuse illumination an easily integrated tool for the modern vitreoretinal surgeon. I predict that continued evolution of these devices will make them user-friendlier, more cost-effective, and even more widely accepted. RP
|Carl C. Awh, MD, is an ophthalmologist in practice with Retina-Vitreous Associates, PC, of Nashville, TN. He reports significant financial interest in Synergetics and moderate financial interest in Bausch+Lomb. Dr. Awh can be reached via e-mail at email@example.com.|
Retinal Physician, Issue: November 2010