Vitreoretinal surgery has evolved considerably from the first days of vitrectomy. The first cutters described by Robert Machemer were 17-gauge and needed a 2.8-mm sclerotomy for placement. After the initial surgeries, Machemer and his colleagues separated the infusion from the cutter to create the modern 3-port pars plana vitrectomy.
Today, retinal surgeons have access to a wide variety of microincision vitrectomy surgery (MIVS) instrumentation in their toolbox, from ultra-small-gauge cutters to different illumination mechanisms. It may sometimes seem daunting to become familiar with the intricacies associated with the different tools. However, knowing the peculiarities and possible uses of different instruments increases the chances of having excellent outcomes in a wide array of pathologies. In this article we will discuss different instruments available in the retinal surgery toolbox.
The most important part of any surgery is visualization. Without an outstanding view, the simplest parts of the surgery can become extremely challenging. It is therefore critical to familiarize yourself with the most common platforms used.
Most surgeons in the United States currently use noncontact visualization systems such as the BIOM (Oculus Surgical) and Resight 700 (Carl Zeiss Meditec) for widefield viewing. The biggest advantage of using noncontact systems is the ability to operate without an assistant. They also allow excellent theoretical 130 degrees of visualization and the capability to work in the far retinal periphery without prisms. Furthermore, this technology allows quick exchange from anterior-segment surgery to posterior-segment visualization.
The noncontact visualization platforms also allow quick exchange of lenses to perform high-magnification macula work. However, one drawback is that the lenses may fog easily and do not provide with the widest or most magnified views. Furthermore, noncontact wide-angle viewing of the periphery requires much greater ocular rotation and instrument flex, which is a concern when using smaller-gauge instruments.
The Resight 700 system can magnify and focus with the microscope pedal. This allows quick visualization in the retinal periphery, in the macula, and when complex pathology is present.
Victor M. Villegas, MD, is Assistant Professor of Clinical Ophthalmology in the Department of Ophthalmology at the Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida and at the Department of Ophthalmology, University of Puerto Rico, San Juan, Puerto Rico. Timothy G. Murray, MD, is the founder of Murray Ocular Oncology and Retina in Miami, Florida. Dr. Villegas reports no related disclosures. Dr. Murray reports research activity with Regeneron, personal fees from Alcon, and fees from the National Cancer Institute. Reach Dr. Villegas at email@example.com.
Various contact lenses are currently available from different manufacturers. Wide-angle contact lenses allow the widest angle of visualization and the sharpest image. Because they are touching the eye, a contact lens allows correction of corneal aberrations and therefore provides unparalleled visibility. Furthermore, due to the shortest possible working distance, true 130 degrees of visualization is possible. We currently use wide-angle contact lenses for primary repair of giant retinal tears and pediatric vitreoretinal surgery.
Several companies have disposable contact lenses with stabilizing legs that allow for magnified 25 to 36 degrees of visualization. In certain situations, one or more of the stabilizing legs may be trimmed off for a perfectly customized fit. Magnification ranges from 0.8 times to 1.5 times.
Aspheric contact high-resolution vitrectomy ACS Lenses (Volk Optical) deliver the highest resolution direct image of the central retina due to the use of high-index glass. These lenses are suited for repeated steam sterilization with no material degradation and can be used with or without suture rings. High-resolution contact lenses can be useful for membrane peeling, transvitreal choroidal biopsies of the posterior pole, macular hole surgery, posterior hyaloid stripping in pediatric cases, and complete fluid-air exchange when complex pathology is present.
Microincision vitrectomy systems (23-, 25-, and 27-gauge) have evolved significantly over the last decade (Figure 1). The advantages of these microincision systems include improved safety by reducing iatrogenic breaks due to peripheral traction during insertion and removal of instrumentation through the trans-scleral cannula system. The most commonly used systems in the US market are the Constellation (Alcon), EVA (Dutch Ophthalmic), and the Stellaris PC/Elite (Bausch + Lomb). All of them offer phacoemulsification and vitreoretinal capabilities, and they are equipped with a 532-nm laser.
The Constellation (23-, 25-, and 27-gauge) provides the ability to control duty cycle and flow vacuum independently. It also boats a bright Xenon light source. The widespread availability of this system is arguably the most important feature since the majority of US-trained surgeons have had experience with this platform.
The EVA (23-, 25-, and 27-gauge) system has recently gained traction in the US retina community mainly due to the revolutionary fluid control system that uses valve timing intelligence. This technology eliminates the risk of unwanted pulsation or unwanted flow seen in peristaltic pumps. The vacuum and flow modes coupled with a 2-dimensional cutter gives the surgeon a new level of control. The LED illumination in this system will last longer than other systems, and color tinting options allow the surgeon variable tissue contrast for enhanced visualization. However, some surgeons may still prefer the xenon lighting system due to warmer color tones.
The Stellaris PC (23- and 25-gauge) is the only vitreoretinal surgical system that comes with a dual light source (xenon and mercury) and surgeon-selected color filters that allow for differentiated viewing designed to enhance the surgeon’s ability to see ocular tissue better under various surgical conditions. However, this platform is not available with 27-gauge trocar-cannula systems. The newest Stellaris Elite is available with 27-gauge trocar-cannula systems and a variety of cutters. The Sterallis Elite is also the only system with a hypersonic vitrectomy probe.
The advent of valved trocars has improved the fluidics of vitrectomy by preventing aqueous reflux through the open cannula. The surgeon may experience difficulty introducing instruments, such as the soft-tipped extrusion cannula, through the valved cannula. Techniques to overcome this difficulty include the push-pull technique or displacement of the valved leaflets. The stabilization of the fluid dynamics during surgery outweighs any difficulties, especially when complex pathology is present. The Constellation, Stellaris PC/Elite, EVA systems offer valved cannulas; however, only with the EVA system can the surgeon quickly remove/place the valves during surgery.
Valved systems also help to stabilize IOP during surgery, minimizing the risks of intraoperative and postoperative maculopathy, choroidal detachment, and choroidal hemorrhage. Patients who have undergone refractive cataract surgery with loss of lenticular material may benefit from the minimal refractive changes and enhanced visual rehabilitation following surgery with small-gauge trocar systems.
One of the most important tools in the vitreoretinal surgery toolbox is the vitreous cutter. It allows safe and effective dissection of the hyaloid near the retina, membrane peeling, core vitrectomy, and vitreous biopsy. Several factors have been identified that affect tractional forces in retina surgery, including cutting speed, distance from the retina, aspiration rate, and duty cycle.
The Constellation’s newest cutter stands out because it performs 10,000 independent cuts per minute and has multiple gauge options. The increased cutter speeds minimize turbulence and may decrease peripheral traction and iatrogenic breaks. The latest cutter for this platform, the Ultravit, has also been designed with a bevelled tip and a larger cutting port opening, which facilitate higher aspiration rates and easier dissection of epiretinal membranes or when cutting close to the retina.
Recently, DORC International developed a new 2-dimensional cutter that allows up to 16,000 cuts per minute. This 2-dimensional cutting maximizes efficiency, and the reduced turbulence increases shaving safety. This technology is available in multiple gauges (23-, 25-, and 27-gauge). This cutter, coupled with valve timing intelligence, enhances safety and control while shaving close to the retina.
The Stellaris PC system’s cutter cuts 5,000 times per minute and is available in 23- and 25-gauge. This may represent a disadvantage when cutting close to the retinal surface. The new Steralis Elite cutter has a cut rate of 7,500 cuts per minute, which effectively becomes 15,000 cuts per minute while using a 2-dimensional cutting system.
The most novel instrument regarding vitreous cutters is the new 23-gauge hypersonic vitrectomy probe exclusively compatible with the Stellaris Elite (Figure 2). This probe liquefies the vitreous instead of cutting it. This may provide a number of advantages compared with conventional pneumatic guillotine cutters because of its unique design features and mechanism of action. The technology utilizes a disposable handpiece and single-lumen probe that provides a 100% open port, allowing for constant flow. This technology may change the way we approach retinal surgery, especially in complex cases with a highly adherent vitreous, such as in pediatric patients.
A major technical hurdle has been the development of a fragmatome compatible with 23-gauge and smaller cannula systems. The most widely available fragmatome is still 20-gauge, and many surgeons prefer to open a 20-gauge sclerotomy with the vitreoretinal blade to use the fragmatome.
However, we have found that a perpendicular 23-gauge trocar incision allows for the placement of a 20-gauge fragmatome in most cases. If difficulty is experienced during fragmatome introduction, opening the incision site with either the trocar blade or a 20-gauge vitreoretinal blade can be considered.
A variety of infusion cannula tips is currently available. In pseudophakic adults, we routinely use the 4-mm infusion tip. However, in phakic patients, especially in the pediatric population, we routinely use 2.5-mm infusion cannula tips. 6.0-mm infusion cannula tips are available and may be preferred in aphakic patients.
A wide array of surgical forceps choices are commercially available for different surgical needs.
Internal limiting membrane (ILM) forceps have a small platform at the tip to peel fine membrane and/or the ILM. They can be used to perform the pinch-peel technique or can be coupled with a diamond-dusted membrane scrapers or loop. Most ILM forceps on the market today are asymmetrical and therefore the tip angle conforms to the retina only at the most distal area for better visualization while grasping tissue.
Serrated forceps are designed to manipulate heavy membranes. They are the most widely used forceps in complex cases of PVR or diabetic retinopathy. When maximum grip is needed, serrated forceps are an easy choice.
Micro-textured grasping forceps (Figure 3), a variation of the serrated forceps, allow secure grasping of fibrous or adherent membranes while minimizing trauma to tissues. They have become our forceps of choice in complex cases of diabetic retinopathy.
Horizontal scissors are commonly used to cut retinal bands and tractional components close to the retinal surface. Angled scissors most commonly follow the contour of the eye to minimize retinal trauma during vitreoretinal interface manipulation. Currently, some manufacturers have illuminated horizontal scissors that are particularly useful during bimanual surgery. Scissor illumination minimizes the need for chandelier placement.
Vertical scissors are commonly used in the most complex proliferative cases with multiplane tractional bands. Vertical scissors may have a sharp anterior edge to optimize close dissection, tissue segmentation, and delamination techniques.
DIAMOND-DUSTED MEMBRANE SCRAPERS
One of the more challenging maneuvers associated with removal of the epiretinal membrane (ERM) and the ILM is safely creating an edge to lift the membrane prior to peeling. Whether you use a pick, forceps, or a diamond-dusted membrane scraper, the goal is the same: to consistently produce a precise edge for rapid, complete peeling.
The nitinol flex loop (Alcon) is effective in providing optimal scraping force and minimizing retinal trauma while creating ILM traction (Figure 4). This loop can be fully or partially retracted to adjust the force applied to the retina as needed. It is also compatible with valved and nonvalved cannulas. At our institution, we have used the loop for ILM removal, ERM dissection, posterior hyaloid separation during retinal detachment repair, and to hold dislocated lenses in the posterior segment.
Bausch + Lomb has also developed multiple membrane scrapers including the Tano, Stiff Tano, Retractable Tano, and Adjustable Tano with Pick. DORC International has the Extendible Diamond Dusted Sweeper, which is similar to the Bausch + Lomb scrapers. These stiffer membrane scrapers can be particularly useful for thick epiretinal memebranes. However, with very delicate surgery, the nitinol flex loop is preferable.
Endoilluminators have evolved significantly during the last 10 years. Different light sources are also available: xenon, mercury vapor, and LED light. These allow brighter illumination using smaller gauges. Light filters can also be used to improve safety and possibly enhance tissue visualization.
Currently, the most widely available endoilluminators provide focal illumination. Newer endoilluminators allow widefield illumination, which facilitates visualization especially in the retinal periphery. A drawback of the wider endoilluminators is that during fluid-air exchange, they can cause significant glare. With focal endoilluminators, using indirect illumination can minimize glare, especially when working under air.
Alcon, DORC International, and Bausch + Lomb offer a wide variety of endoilluminators that span from focal to wide angle. Newer fiber optic illuminators from all major manufacturers minimize glare while optimizing visualization. Wide-angle fiberoptic illuminators may be the preferred choice during peripheral dissection.
Chandeliers (Figure 5) are now available in a trocar-cannula system (23-, 25-, 27-gauge) from all major manufacturers. They allow bimanual surgery when complex pathology is present. They are particularly useful during complex tractional retinal detachment repair or when performing direct perfluorocarbon to silicone oil exchange. They may become less useful during vitrectomy as other instruments (scissors and forceps) become available with illumination. The smallest chandelier available is the Oshima Dual 29-gauge chandelier (Bausch + Lomb).
Chandeliers can also be used to perform a primary buckle procedure without vitrectomy. The technique allows easy visualization of the break with the surgical microscope during placement of the primary buckle. The trocar-cannula system also allows using an illuminated endolaser to treat the tear after external drainage without having to perform another sclerotomy. This can be performed in all systems. A variation of this technique involves using the Shielded TotalView Endoillumination Probe, an illuminated scleral depressor (DORC International), to localize the tear.
A new variation of the chandelier is the illuminated infusion cannula available from both Alcon and Bausch + Lomb. This dual-purpose instrument improves visualization and is especially useful in bimanual surgery and peripheral dissection. DORC International offers a combined 23-gauge Eckardt Multi-Fiber Endoillumination Probe that works as chandelier and as an endoilluminator. These multifunctional illumination devices minimize the expense of having to use 2 different instruments while expanding the visualization capabilities and improving surgical outcomes.
SOFT TIP AND BACKFLUSH
Soft-tip extrusion cannulas are valuable to the retina surgeon in numerous situations. They have become a mainstay for management of retinal detachment. Smaller gauge soft-tip cannulas (27-gauge) are extremely useful to decrease the size of the retinotomy during retinal detachment repair. Soft-tip cannulas also minimize the possibility of traumatic optic neuropathy during complete fluid-air exchange. Newer soft-tip cannulas are available with retractable tips to avoid the difficulty associated with inserting through a valved cannula.
The backflush cannula is similar to the soft-tip cannula, but it allows for a backflush if retinal incarceration is present at the tip. The backflush mechanism may also be used to disperse fluids resting on the macula, such as blood or medications. It is our tool of choice to perform passive aspiration of subretinal fluid and perform fluid-air exchange.
Scleral buckling has fallen out of use mainly due to the increased efficiency of vitrectomy systems. However, scleral buckling is a valuable tool in many situations. The most commonly used bands are the 240 (2.5 mm wide), 241 (3.5 mm wide), and 242 (4.0 mm wide) bands. Multiple encircling elements are available depending on the extent and the location of the area to be imbricated. Wider bands are difficult to tunnel through the sclera and are typically sutured. Thinner bands may be tunnelled or sutured. We routinely perform primary scleral bucking with or without vitrectomy in inferior rhegmatogenous retinal detachments, giant retinal tears, and pediatric retinal detachments.
Endolasers are a key element in modern vitreoretinal surgery. They are mostly used to treat retinal defects; however, they can also be used to cauterize bleeding vessels, ablate retinal and choroidal tumors, and perform endophotocyclocoagulation. Initially, endolasers were straight throughout. However, newer endolasers have a curved tip to allow better access to the far periphery.
Articulating endolasers (Alcon) allow continuously adjustable articulation up to 45 degrees, providing broader access than conventional laser probes (Figure 6). This may improve the ability to laser the retinal periphery. The semi-rigid nature of this probe minimizes the difficulties encountered when inserting through valved cannulas.
Similarly, Bausch + Lomb have also developed an illuminated directional laser probe that facilitates insertion through valved cannulas in the straight position. Once in the eye, the fiber extends and arcs up to 90 degrees to provide easy access to the far periphery. A disadvantage of retractable and articulating probes is the increased range of motion that may limit stability in certain situations. Some surgeons may still prefer the older curved illuminated laser, which is available in all the major platforms.
Recently, Bausch + Lomb introduced the Soft-Tip Aspirating Laser Probe, a straight laser probe that allows endolaser and both active and passive aspiration. This instrument allows easy fluid-air exchange, subretinal fluid drainage, and laser of tears during vitrectomy for retinal detachment repair without the need to perform instrument exchange. This minimizes peripheral traction and decreases the total surgical time. Similarly, Alcon’s new dual-function aspirating laser probe, the Chang Soft Curved Aspirating Laser Probe, is curved to facilitate laser ablation of the retinal periphery.
TWO-PORT SURGERY AND MULTIFUNCTIONAL INSTRUMENTATION
A new generation of multifunctional instruments is available that minimizes instrument exchange during surgery and decreases surgical time. For example, illuminated picks (available from Alcon, Bausch + Lomb, and DORC International) facilitate dissection of difficult membranes without sacrificing direct visibility. The Ryan Illuminated Visco Injector (Alcon) may be particularly useful in complex diabetic tractional retinal detachments. Illuminated bipolar cautery (Alcon, Bausch + Lomb) is extremely useful when performing extensive retinectomies. The 3-function Tissue Manipulator (Alcon) allows illumination, aspiration, and coagulation and may be a great advantage during rhegmatogenous retinal detachment repair. In select complex trauma cases, Bausch + Lomb’s distinctive 20-gauge microfiber illuminated vitrector/sleeve may help visualize peripheral pathology. Irrigating endoilluminators (Alcon, Bausch + Lomb) effectively create a 2-port vitrectomy and may be an ideal setup for macular surgery, endophthalmitis cases, and vitreous biopsies.
Currrently, Bausch + Lomb offers the largest variety of illuminated instruments, which include a membrane rake, end gripping forceps, horizontal scissors, microforceps, microserrated end gripping forceps, and horizontal small curved scissors. The variety of instrumentation may be an important consideration when assessing a vitreosurgical platform.
The advent of multifunctional instruments, in particular illuminating other instruments (forceps, scissors, vitrector, rake, aspiration tip, and infusion) and adding infusion to the endoilluminator, will revolutionize vitreoretinal surgery. 2-port MIVS and multifunctional instrumentation may decrease morbidity by decreasing surgical time and instrument exchanges. Furthermore, decreasing the amount of instrumentation and time per surgery may increase surgical volume in some surgical centers that could provide the financial incentive to invest in the next generation of vitreoretinal systems.
Intraoperative OCT (iOCT) is currently one of the most high-end tools any retinal surgeon can have in the operating room (Figure 7). iOCT is most valuable when the macula cannot be visualized prior to surgery, such as when a vitreous hemorrhage is present. However, it also improves the ability of the surgeon to complete visualize tractional components during membrane peeling. This commercially available technology (Zeiss Rescan 700 and Leica EnFocus), similar to the revolution in medical retina, will dramatically improve our decision-making during MIVS.
The latest visualization system (Ngenuity; Alcon) developed for vitreoretinal surgery has been centered on computer technology. The image is processed to enhance stereopsis and magnification via a heads-up display and filtered to enhance color and contrast. This technology effectively creates a superior image that facilitates the surgical craft and improves teaching. The interplay between light sources, filters, dyes, and image computer processing is currently receiving greater attention due to the availability of this technology. Current research studies are evaluating the potential for improved outcomes.
MIVS instrumentation has changed dramatically since the initial days of vitrectomy. Improvements in visualization have made intimidating tasks routine. Small gauges and better instrumentation have allowed faster visual rehabilitation, patient comfort, increased surgical safety, and superior outcomes. At our institution, rhegmatogenous retinal detachments repair is achieved in over 90% of primary surgeries. Our ability to achieve excellent outcomes is directly related to the capacity to adapt different surgical techniques at different times. We highly recommend becoming acquainted with the vitreoretinal instruments in your surgical toolbox to improve anatomical and visual outcomes. RP