- Event Horizon
- Innovations in AMD Management
- Symptomatic Vitreomacular Adhesion and Ocriplasmin: Patient Selection and Management
- The Role of 27-Gauge Surgery in Modern Retina Practice
- When the Mind's Eye Goes Dry
- A Strategic Partner in Product Development
- Advances in Drug Delivery
- Dropless Procedure Redefines Cataract Surgery
- The Next Generation of Drug Delivery
- State of the Union: Contact Lenses in 2015
- Update on Soft Contact Lenses
- Pearls for Success With Multifocal Contact Lenses
- Moran Minute: The Art of Contact Lens Fitting
- Daily Disposables: Technology Sells Itself
- Exploring the Lifestyle Benefits of Orthokeratology
- Extended Range of Silicone Hydrogel Lenses to Address High Ametropias
- Making the Switch From One EHR System to Another
- Tips for Effective Eye Care Practice Blogging
- Employment With Visual Disability
- The Drug Development Path
It is my distinct pleasure to announce the first installment of “Modern Retina.” Our mission for this column is to update our readers on current concepts and developments in retinal care as it relates to everyday practice issues for both specialists and primary eye care doctors. This year we will focus on age-related macular degeneration (AMD) in terms of current paradigms for treating the wet form of the disease, new pipeline molecules to treat both dry and wet AMD, as well as the role of nutriceuticals. In addition, we will present the multiple new treatments for diabetic macular edema, as well as agents for preproliferative and proliferative diabetic eye disease. We will pursue concepts that relate to vitreomacular traction, including diagnostic aids as well as pharmacologic and surgical treatment. Finally, we will report on new advances in retinal surgery and visualization in terms of what to expect from the retinal operating suite of the future and what benefits patients will receive from these changes. Whenever possible, we will pursue a multimedia approach with links to video and or audio presentations. Our first article looks at 27-gauge surgery and how small-gauge procedures help minimize invasiveness and still achieve excellent results. We look forward to reporting these important advances.
As vitreous surgery has evolved, procedures have become safer and more efficient, permitting better surgical outcomes and broadening the range of surgical pathologies that can be successfully treated. The minimally invasive nature and precision of small-gauge, high-flow vitrectomy instrumentation represent critical advances in our ability to achieve better outcomes. The development of 27-gauge vitrectomy surgical platforms is the most recent advance in the general trend toward smaller, more precise instrumentation. To see videos of the systems discussed, go to eyetube.net/?v=epipo and
THE ROAD TO 27 GAUGE
The original vitrectomy system, introduced by Machemer in 1971, employed 17-gauge instruments that measured 1.5 mm in diameter and were placed through 2.3-mm sclerotomies.1 The initial cut rate was 60 cuts per minute (cpm). About 3 years, 20-gauge vitrectomy surgery was developed, and this instrumentation remained the mainstay of vitreous surgery from the mid-1970s until about 10 years ago. Sclerotomies that measured approximately 1.2 mm and accommodated 0.89-mm–diameter instruments were employed for 20-gauge surgery.
In 2002, 25-gauge vitrectomy was introduced by Fujii et al.2 The early 25-gauge instruments were relatively flexible, which limited their use in complex cases or cases with peripheral pathology.2,3 In the next several years, instrument rigidity and ergonomics were significantly improved, permitting a wider variety of surgical pathology to be successfully addressed. In addition, Eckhart et al developed a 23-gauge surgical platform that permitted greater instrument stability and made possible faster core vitreous removal.4 The sclerotomy sizes for 23-gauge and 25-gauge surgical platforms are 0.72 mm and 0.55 mm, respectively.
Figure 1. Comparison of vitrectomy handpiece size and design. The 27-gauge vitrectomy handpiece is less than 50% of the size of the 20-gauge handpiece. Port diameter of the 27-gauge instrument is 60% of that of the 20-gauge probe, enhancing the fluidics of the smaller probe when combined with improved duty cycle and flow rates. The distance from the port to the tip of the vitrectomy handpiece is shortened with 25- and 27-gauge instruments to permit more precise removal of preretinal tissue.
Figure 2. Alcon 27-gauge Constellation surgical platform. Alcon has produced a robust 27-gauge surgical platform with a variety of vitrectomy instruments. These instruments include vitrectomy handpiece, valved trocars, soft tip aspiration probe, light source, backflush brush, forceps, scissors, laser, and diathermy.
Figure 3. Key features of the Dutch Ophthalmic 27-gauge twin duty cycle vitrectomy instrument. The dual cutting action of the instrument permits efficient removal of vitreous while minimizing preretinal traction. Aspiration flow rate can be increased two- to threefold with reduced surge turbulence near the port.
Figure 4. Evolution of trends in vitrectomy surgery. Both US and international surgeon respondents typically have transitioned away from 20-gauge sutured surgical approaches to 23- and 25-gauge smaller-incision surgery. Among
US surgeons there is a slightly higher preference for 25-gauge surgery relative to non-US surgeons.
Although 23- and 25-gauge systems are less invasive than 20 gauge, there have been reports of increased postoperative endophthalmitis and hypotony rates with these types of instruments.5 Air tamponade and two-step trocar placement have helped to diminish these rates, but there appears to be an unmet need for true sutureless vitrectomy surgery that can be employed under all conditions including use of fluids and heavy liquids.
Advances in instrumentation for 23- and 25-gauge microincision vitrectomy surgery (MIVS) paved the way to permit even smaller, less invasive surgical options. As the lumen of these instruments decreased, more efficient fluidics and vitreous removal were developed, with higher flow rates, higher vitrectomy cutter speeds, and improved duty cycles. Light sources have also been improved, with the development of widefield light pipe sources and small-lumen chandelier light sources. Improved hydraulics now permit relatively facile placement and removal of heavy liquids. Finally, improved materials science has increased instrument shaft stiffness to permit easier placement and better accessibility to address peripheral retinal pathology.
Based on these advances and the potential of less invasive and true sutureless vitrectomy surgery, a 27-gauge surgical platform was described in 2010. That first report described 31 cases, including eyes with epiretinal membrane, macular hole, vitreous opacity, diabetic vitreous hemorrhage, and traction detachment.6 The diameter of the 27-gauge sclerotomies was designed to be 0.4 mm so that sclerotomies required no suture closure. No postoperative hypotony was reported. Anatomic success was achieved in all eyes without the need for sclerotomy enlargement, and mean case time was 34 minutes (range 10-88 minutes).
Early encouraging data prompted further development of this ultrasmall MIVS 27-gauge system to further refine instrumentation and permit another option for vitrectomy surgery. Two companies now offer full 27-gauge vitrectomy platforms.
Because Poiseuille’s law states that flow rate is related to the radius to the forth power, there was concern that reduction in the lumen diameter for 27-gauge instrumentation might adversely affect infusion and aspiration. The initial infusion and aspiration rates of the Alcon 27-gauge system, measured with balanced salt solution, were 61% and 81%, respectively, of the rates with the company’s 25-gauge system.
Adjustments were made to the 27-gauge Alcon instrumentation to achieve improved fluidics that were more comparable to 25-gauge surgical parameters. These included increase in port size area, increase in vitreous cutting rate, higher duty cycle, and improved aspiration (Figure 1).
Currently, the 27+ Constellation (Alcon) vitrectomy probe operates at a cut rate of 7,500 cpm, significantly higher than the initial cut rate of 2,500 cpm, producing a duty cycle of 50% and approximating the infusion and aspiration efficiency of modern 25-gauge surgical technology. The flow rate in balanced saline solution is further enhanced by the device’s ability to increase aspiration to 650 mm Hg.
Clinically, the 27-gauge vitrectomy instrument is marginally slower for core vitreous removal than larger-gauge systems, but modifications have allowed effective release of adherent vitreomacular adhesions. Similar to the Dutch Ophthalmic platform (described later), the faster cutting rate permits reduced vitreous traction, thereby likely lowering the risk of intraoperative retinal tears. The Constellation system has refined many of these modifications and developed a 27-gauge surgical platform to address a wide variety of surgical pathologies with similar characteristics to those of second generation 25-gauge surgical technologies (Figure 2).
DUTCH OPHTHALMIC PLATFORM
The Dutch Ophthalmic EVA 27-gauge system uses a one-step microvitreoretinal blade cannula system to lower the impact of trocar placement by 50% compared with previous design models. A new removable closure valve is also easier to visualize when inserting instruments.
The Dutch Ophthalmic 27-gauge vitrectomy instrument uses a twin-duty cycle cutter to improve the safety and efficiency of vitreous removal. More vitreous can be removed because a larger rectangular aperture has been incorporated in the inner tube of the vitreous cutter. In addition, cutting speed is doubled with the use of two sharp edges, reducing traction on surrounding tissue and allowing increased aspiration flow up to three times the normal rate while reducing “surge” turbulence (Figure 3). Results in a small prospective consecutive case series showed that the 27-gauge instrumentation using the Bright Star Xenon Illumination System (Dutch Ophthalmic) achieved good anatomic and visual outcomes in all patients with short term follow up.7
Retina specialists have progressively shifted away from 20-gauge vitrectomy toward the use of smaller-gauge sutureless systems that reduce surgical trauma and average surgical duration, leading to statistically significantly better and faster postoperative recovery, as well as increased patient comfort and satisfaction.
The 2013 Preferences and Trends survey of the American Society of Retina Specialists showed that, of both US and international respondents, more than 90% of retina specialists most often use 23- or 25-gauge systems for vitrectomy surgery. Approximately 40% of retina specialists in the United States most often use 25-gauge vitrectomy as their preferred gauge approach, while more than 10% of international specialists and 5% of US retina specialists said that they have tried 27-gauge vitrectomy (Figure 4).
Some believe that the transition to 27-gauge surgery is a natural evolution because surgeons prefer small, self-sealing incisions with better wound construction to permit faster recovery with similar or better patient outcomes that those observed with larger-gauge approaches. This enthusiasm, however, must be balanced against the learning curve that is required for the adoption of 27-gauge surgery because of the more flexible instruments that aspirate marginally less effectively.
Early experience indicates that the outcomes, both anatomic and functional, using 27-gauge pars plana vitrectomy instrumentation, have been excellent, and we now have employed 27-gauge surgery to repair epiretinal membranes, macular hole, vitreomacular traction, and proliferative diabetic retinopathy, with or without scleral buckle and heavy liquids. Patients have minimal to no perception that they have undergone a procedure even in the first few days following 27-gauge vitrectomy for macular pucker.
With careful case selection and after navigating the learning curve for 27-gauge surgery, the benefits include enhanced wound sealing, improved cutting efficiency, reduced surgical trauma, and faster postoperative recovery. All of this results in an overall improvement in surgical efficacy and efficiency, even in challenging vitreoretinal disorders. Moreover, the current instrumentation for smaller gauge surgery achieves higher flow rates, therefore offering greater options for surgeons because of optimal fluidic stability during surgery.
There is a role for each gauge in vitrectomy surgery, but some indications and pathologies are more applicable to 27-gauge surgery. We expect that further innovations and advances in materials design, handling properties, and lighting will over time allow 27-gauge surgery to perform similarly to the current generation of 25-gauge instrumentation, which will likely lead to increased migration toward and better outcomes with the smaller-gauge vitrectomy.
Although 27-gauge MIVS is here to stay, it is not the size alone that matters, it is the clinical outcomes achieved. n
1. Machemer R, Buettner H, Norton EW, Parel JM. Vitrectomy: a pars plana approach. Trans Am Acad Ophthalmol Otolaryngol. 1971;7:813-820.
2. Fujii GY, de Juan E Jr, Humayun MS, et al. A new 25-gauge instrument system for transconjunctival sutureless vitrectomy surgery. Ophthalmology. 2002;109:1807-1812.
3. Lakhanpal RR, Humayun MS, de Juan E Jr, et al. Outcomes of 140 consecutive cases of 25-gauge transconjunctival surgery for posterior disease. Ophthalmology. 2005;112:817-824.
4. Eckhart C. Transconjunctival sutureless 23-gauge vitrectomy. Retina. 2005;25:208-211.
5. Kellner L, Wimpissinger B, Stolba U, Brannath W, Binder S. 25-Gauge vs 20-gauge system for pars plana vitrectomy: a prospective randomised clinical trial. Br J Ophthalmol. 2007; 91:945–948.
6. Oshima Y, Wakabayashi T, Sato T, et al. A 27-gauge instrument system for transconjunctival sutureless microincision vitrectomy surgery. Ophthalmology. 2010;117(1):93-102.
7. Teixeira A, Rezende F, Salaroli C, et al. 27-gauge system for primary vitrectomy to treat rhegmatogenous retinal detachment. Paper presented at: The Association for Research in Vision and Ophthalmology (ARVO) Annual Meeting, 2014; May 5, 2014; Orlando, FL.
Section Editor Derek N. Cunningham, OD
- Director of optometry and research at Dell Laser Consultants in Austin, Texas
- Founding member and chair of the American Society of Cataract and Refractive Surgery’s Integrated Ophthalmic Managed Eyecare Delivery Task Force
- Chief medical editor of Advanced Ocular Care
- Acknowledged no relevant financial interest
Medical Editor Alan Franklin, MD, PhD
- Practices at the Retina Specialty Institute in Mobile, Alabama
- Acknowledged no relevant financial interest