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Twenty-five-gauge sutureless vitrectomy is has gained a respectable niche among retinal surgeons, with a dramatic increase in use over the previous 4 years.
During a recent presentation, Dr. Awh reflected on a question posed to him in 2003 at the annual meeting of the American Academy of Ophthalmology: "Is transconjunctival sutureless 25-gauge vitrectomy the wave of the future or a passing fad?" Five years and thousands of cases later, he and other retina surgeons have demonstrated that 25-gauge vitrectomy indeed has fulfilled much of its early promise. The technique should remain a valuable surgical tool for the foreseeable future because it facilitates the simplest wound construction, is less expensive than 23-gauge vitrectomy, and can address most pathologies, he said. Dr. Awh is president of Tennessee Retina, Nashville, TN.
In 2003, when Dr. Awh predicted that "twenty-five-gauge vitrectomy has a promising future," the American Society of Retina Specialists Preferences and Trends (ASRS PAT) survey found that 70% of retina surgeons had never tried the technique, 18% had tried it but did not own the instrumentation, 7% owned the instrumentation but used it infrequently, and 6% owned and used it frequently, he said. In contrast, the 2006 ASRS PAT survey reported that the majority of surgeons performed 25-gauge vitrectomy for at least some of their cases and that 46.2% performed 25-gauge vitrectomy "frequently."
Although Kaiser and colleagues have reported the rate of endophthalmitis, which is a concern with any sutureless IOP, to be seven cases in 3,100 (0.23%), ten separate published retrospective series on 25-gauge vitrectomy had no cases of endophthalmitis develop reported among 700 surgeries. The University of California, Los Angeles, reported similar results in more than 1,000 surgeries with no cases of endophthalmitis. Dr. Awh reported that in his practice, in which he has performed more than 1,100 surgeries using 25-gauge instrumentation, one case of endophthalmitis developed, for an incidence of 0.09%.
Although the actual risk of the development of endophthalmitis is unknown, Dr. Awh acknowledges that all types of sutureless vitrectomy might reasonably be expected to have a slightly higher risk of endophthalmitis. He emphasized that certain simple precautions can be taken to minimize risk. The use of topical povidone-iodine 5% sterile ophthalmic prep solution applied preoperatively to the conjunctiva is one such precaution. Careful wound construction, with conjunctival displacement, may reduce risk. He also recommends the injection of subconjunctival antibiotic adjacent to the sclerotomies to further separate the conjunctival wound from the scleral wound at the conclusion of surgery.
When to use 25 gauge
Dr. Awh said that although he prefers to perform 25-gauge vitrectomy in about 90% of cases, there are situations in which he opts for other techniques. "There are surgical problems that are not effectively or practically treated with 25-gauge technology," he said, citing that instruments of a larger gauge are needed to remove dense scar tissue, organized hemorrhages, and large foreign bodies.
When confronted with these cases, Dr. Awh said he prefers to use 20-gauge instruments, which are the largest typically available. "For the most complex cases, avoiding sutures is a non-issue. Twenty-gauge instruments and the systems required to use them remain the most versatile, economical, and durable of our treatment options," he said.
Technological improvements in 25-gauge vitrectomy have changed the nature of the procedure from what it was just a few years ago, according to Dr. Awh.
One such improvement is the 25-gauge third-generation vitreous cutter, he said. The latest generation of cutters have dramatically improved flow and increased tip stiffness and allows vitrectomies to be performed more rapidly with reduced vitreous traction. The new cutters have tips that are smaller in diameter, making dissection and delamination of epiretinal membranes easier. Minimal flex is associated with the stiffer cutters. Dr. Awh reports that he is able to remove significant amounts of cortical and nuclear lens material with the newer generation 25-gauge vitreous cutter. The ability to address this complication of cataract surgery without sutures or induced astigmatism, while causing minimal trauma to the ocular surface, is a benefit to the patient and is appreciated by the referring ophthalmologist.
Other improvements have occurred in trocar-cannula systems and illumination sources since 25-gauge vitrectomy first was introduced.
25-gauge or otherwise
When faced with the choice of instrumentation-25-, 23-, or 20-gauge-the choice should be made on a per-case basis, Dr. Awh said. Some surgeons view 23-gauge as "the perfect compromise" between the small 25-gauge instruments and the robust 20-gauge systems, he added.
"To me, 23-gauge seems to be an 'incomplete compromise,'" he said. "Concerns about 25-gauge wound integrity are magnified with the larger 23-gauge wounds, and avoidance of hypotony is more technique-dependent with current 23-gauge systems. At the other end of the spectrum, there are certain cases for which 23-gauge instruments aren't adequate, such as those requiring a fragmatome or large foreign-body forceps. For these cases, 20-gauge systems are superior. In fact, methods to perform 20-gauge sutureless vitrectomy with cannulas also exist and will no doubt be refined in coming years. For less complex cases, I predict that improvements in 25-gauge instrument stiffness and functionality will continue, allowing an increasingly larger percentage of cases to be performed effectively and efficiently with 25-gauge devices." Dr. Awh also mentioned efforts by some surgeons to develop an even smaller 27-gauge vitrectomy system.
Continued surgical goals are to reduce patient discomfort, achieve more rapid visual improvement, increase efficiency, and control costs, Dr. Awh added.
While Dr. Awh acknowledges that the "ideal gauge" does not yet exist, the 25-gauge system remains his preference because it has the simplest wound construction, has proven and improving technology with the ability to address most pathology, currently less expensive than 23-gauge vitrectomy.