Microincision pushes new frontiers in vitreoretinal surgery

Yusuke Oshima, MD, advocates a 27-gauge approach to achieve an uncomplicated, self-sealing wound. Image: Oshima Y

Along with medicine in general, ophthalmology is evolving toward increasingly less invasive techniques. Cataract surgery has led the way, and at the beginning of the new millennium, vitrectomy has followed with a series of innovations, allowing for smaller, sutureless incisions.

The transconjunctival 25-gauge approach was the first to be introduced, in 2002 by Eugene De Juan, MD. The trocar was inserted through the conjunctiva directly into the sclera, allowing for a reduction of incision size from 1.1 mm to 0.5 mm.

“This approach held the advantage of easy entry, with minimal trauma to the conjunctiva, sclera and pars plana,” said Manish Nagpal, MS, DO, FRCS, an OSN Asia-Pacific Edition Editorial Board Member. “All the instruments passed through the sleeve of the cannula, minimizing tissue manipulation and the trauma of repeated insertion and removal. The operating time was potentially shorter compared to conventional 20-gauge vitrectomy. The absence of sutures increased patient comfort, and recovery time was faster, because smaller, self-sealing sutures reduced postoperative inflammation.”

However, the first 25-gauge systems forced surgeons to accept a compromise. Smaller-gauge vitreous cutters had reduced vitreous-cutting ability, reduced caliber instruments were too flexible and fluidics were suboptimal.

“Most importantly, the incisions made by the old trocar and cannula systems were chevron-shaped and tended to leak, leading to potential complications such as postoperative hypotony and endophthalmitis,” Dr. Nagpal said.

Manish Nagpal

With these concerns in mind, industry refined the instruments. The Bausch + Lomb Millennium and Stellaris systems, the Oertli OS3 and the Alcon Constellation and Accurus systems now provide state-of-the-art equipment for 25-gauge microincision vitrectomy, with higher-speed vitreous cutters and more efficient endoillumination probes. The design, geometry and sharpness of microincision vitrectomy instruments have also improved.

Techniques have evolved as well. Conjunctival displacement creates a misaligned wound between the conjunctiva and sclera, and, once the conjunctiva moves back, provides a natural protection over the wound. Oblique, beveled rather than straight trocar insertion leads to better wound closure and prevents vitreous incarceration.

A new, balanced approach

In the meantime, a new, 23-gauge approach was developed and rapidly gained consensus, offering a good balance between 25-gauge and 20-gauge surgery.

“The instruments are stronger, cutting speed and fluidics are better. I use 25-gauge for simpler surgery, like macular hole and macular pucker. For more complex surgery, where more manipulation is required, I prefer 23-gauge,” Dr. Nagpal said.

In his opinion, 90% of vitreoretinal procedures can be performed with the 23-gauge approach.

“In our setting, we still use 20-gauge for about 60% of the procedures, because we have a fellowship program and want our trainees to learn the basic principles of standard, conventional 20-gauge vitrectomy approach before they start on [microincision vitrectomy]. We use 23-gauge in approximately 30% of the cases and 25-gauge in the remaining 10%. However, the proportions of 20- and 23-gauge would be at least reversed if we did not have to train new surgeons,” he noted.

Jong Jian Lee, MD, FRCS, retinal consultant at Raffles Hospital in Singapore, was one of the first surgeons who pioneered the 23-gauge minimally invasive retinal eye surgery in Asia.

“I started nearly 5 years ago, and I use it now in 90% of my patients. I hardly ever use 25-gauge because it is limited in scope. The instruments are too delicate to handle complex retinal conditions. The 20-gauge approach is great for instrumentation, but since it requires a significantly longer time to get into the eye and a longer recovery time, I use it in a small number of patients, mainly complicated ocular trauma cases,” Dr. Lee said.

Dr. Lee has treated many patients with the 23-gauge approach, using the Alcon Accurus system. He said that surgery with this system is fast and safe. The trocar system protects the vitreous base from the entrance and exit of the instruments.

“It prevents them from causing trauma to the vitreous base, reducing the incidence of retinal tear,” Dr. Lee said.

Also, other complications are rare. Sclerotomies are small and seal well, so leakage, hypotony and infection are not an issue.

“I haven’t had a single case of endophthalmitis in all these years,” he said.

Iatrogenic cataract may be caused by the cannula touching the lens, but it can be avoided through careful maneuvers.

“Point down vertically toward the posterior pole with your cannula. A wrong angulation may result in contact with the lens, resulting in cataract formation,” Dr. Lee said.

One of the advantages of the 23-gauge vs. 25-gauge approach is the possibility of removing more vitreous. The instruments are stronger, rotate better and can reach further in the periphery. The 23-gauge cutter also has a higher cutting speed. According to Dr. Lee, about 90% of the vitreous can be removed.

Incision making is key

Incision making is the key feature for successful sutureless vitrectomy, Dr. Nagpal said.

“We have experimented with several techniques. We have finally adopted a two-step biplanar approach, entering the sclera in an oblique fashion and then continuing perpendicularly. This angulated approach allows the wound to seal better, preventing wound leakage and wound-related complications,” he said.

The present EdgePlus design of Alcon trocars has made a lot of difference to wound integrity, he noted. Linear incisions performed with EdgePlus are very similar to the 20-gauge but are smaller, do not need sutures and close much better.

“However, if at the end of surgery we have concerns about the incision, we suture it. It happens very rarely, but I would recommend any surgeon who is going through a learning curve not to promise their patients that surgery will be sutureless. It is better to be on the safe side. Incision is the most important step in small-gauge. Essentially all other steps are the same, apart from having smaller instruments.”

Dr. Nagpal uses an ASICO Trocar Fixation Plate while making the incision. This instrument has an incorporated caliper to measure distance from the limbus and serrations on the undersurfaces, allowing a good hold on the conjunctiva for misalignment over the proposed scleral entry.

Dr. Lee uses the Eckardt pressure plate (DORC) to displace the conjunctiva 1 to 2 mm laterally. He then holds it firmly against the sclera while inserting the trocar.

“I do an angulated entry, going in tangentially, 30° to 40° from the surface, about 3.5 mm posterior and parallel to the limbus, followed by a vertical entry. This approach allows the wound to seal better,” he said.

Particularly in elderly patients who need gas tamponade and face-down posturing, Dr. Lee said he prefers to put in a temporary suture, “to be on the safe side.”

“It takes a couple more minutes, but it’s something to consider in order to prevent wound leakage due to pressure on the eyeball when posturing in a face-down position. The sutures will spontaneously reabsorb in a few weeks,” he said.

Present and future of vitrectomy machines

“The advent of small-gauge instrumentation, which started with basic features and now encompasses almost the entire range of features that are available with larger-gauge systems, has definitely made a lot of difference both in terms of meeting surgeons’ requirements and patient expectations, without compromising surgical results,” Pramod S. Bhende, MD, senior consultant at the Medical Research Foundation’s Sankara Nethralaya eye hospital in Chennai, India, said.

Pramod S. Bhende

Dr. Bhende uses Alcon and Bausch + Lomb systems equally often and finds both equally comfortable.

“The modular system in Bausch + Lomb, where modules can be added or replaced without disturbing the entire system, is definitely an advantage. I had the chance to see the Stellaris prototype last year. I hope it proves to be a sturdy machine with all the sophistication that is promised, including the 5,000-cpm pneumatic cutter, dual illumination with xenon and mercury vapor sources, viscous fluid injectors, venturi pump, cordless foot pedal with possibility of remote software updates and preventive maintenance,” he said.

Dr. Bhende works in a setting that involves multiple users of a single machine and a huge variety of surgical cases. For him, his colleagues and his maintenance staff, versatility and durability are essential features.

Dr. Nagpal is a longtime Alcon user and is satisfied with the performance of Alcon instruments.

“Currently we use the new Alcon Constellation system and the Accurus in some cases. The Constellation has been built for small-gauge specifically and has faster fluidics and more accurate infusion pressure. The vitreous cutter works at a speed of 5,000 cpm. It is extremely safe and allows us to go very close to the retina,” Dr. Nagpal said.

The issues of cost and availability remain crucial for the popularization of small-gauge surgery in the future, according to Dr. Bhende.

“Though the basic vitrectomy packs of Alcon and Bausch + Lomb [microincision vitrectomy] systems have comparable prices, the overall cost is still high compared to 20-gauge instruments,” he said.

“In a real-world situation, even in a developed country, cost is a crucial factor for the patient who needs to pay for the surgery, for the surgeon or the institute that buys the equipment, and for the insurance companies or governments who reimburse the costs,” he said. “Special instruments need to be available more easily without the need to wait for long periods of time for procurement.”

Advantages of a 27-gauge approach

According to Yusuke Oshima, MD, associate professor at Osaka University Graduate School of Medicine, a truly self-sealing wound for uncomplicated and yet effective microincision vitrectomy can be obtained with an even smaller, 27-gauge approach.

“We have been using 27-gauge needles for many years in post-vitrectomy treatments, such as performing transconjunctival fluid-fluid or fluid-air exchange. No wound-related complications have been reported. Therefore, 27-gauge may be the maximum size for achieving perfect and easy self-sealing wounds,” he said.

A unique set of 27-gauge instruments, developed in collaboration with DORC, was used in a pilot study. A total of 31 eyes of 31 patients with a variety of retinal diseases, including epiretinal membrane proliferation, idiopathic macular hole, diabetic macular edema and nonclearing vitreous opacity, were successfully treated.

“Outside the study, I have personally treated about 100 patients with not only macular diseases but more challenging conditions like rhegmatogenous retinal detachment and diabetic traction retinal detachment,” Dr. Oshima said.

“Complex techniques for creating a self-sealing wound, such as angled insertion, are no longer needed. Even the trocar-cannula system, although available, is not required in simple cases. You simply go through the conjunctiva and sclera with a 27-gauge needle, inserting it vertically. The incision seals completely after the procedure. I have had no case of hypotony, wound leakage or vitreous incarceration,” he said.

Powerful light sources, such as xenon and mercury vapor light, have enabled the use of 27-gauge optic fiber for endoillumination. According to Dr. Oshima, many stiffer 27-gauge instruments have also been developed for intraocular manipulations.

The only disadvantage is cutting efficiency, he said. The 27-gauge vitreous cutter has about 80% of the efficiency of 25-gauge cutters. However, even with this limited performance, he was able to carry out vitrectomy effectively and accurately. The average operating time was 30 minutes.

“Some surgeons might find that the instruments are fragile and not easy to handle. I don’t think this should be a problem in expert hands. With the wide-angle viewing system, you don’t need to move the eye a lot, and you only need small, controlled movements with your instruments,” he noted.

With a few refinements, the technique might gain popularity in the near future, Dr. Oshima said.

“Highly efficient 27-gauge cutters may not be just a dream. New-generation machines with a dual-actuation technology allow for ultra-high cutting rate with duty cycle control. If this technology was applied to 27-gauge, we would be able to achieve a much higher performance in the future,” Dr. Oshima said. – by Michela Cimberle

Is the risk of endophthalmitis too high in sutureless transconjunctival vitrectomy?

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• Pramod S. Bhende, MD, can be reached at Department of Vitreoretinal Surgery, Sankara Nethralaya, Medical Research Foundation, 18 College Road, Nungambakkam, Chennai 600006, Tamil Nadu, India; +91-44-28271616; e-mail: pramod1999@yahoo.com.
• Jong Jian Lee, MD, FRCS, can be reached at Raffles Hospital, 585 N. Bridge Road, Singapore 188770; e-mail: jongjian@hotmail.com.
• Manish Nagpal, MS, DO, FRCS, can be reached at the Retina Foundation, Near Shahibaug Underbridge, Rajbhavan Road, Ahmedabad 380004, Gujarat, India; +91-79-22865537; fax: +91-79-22866381; e-mail: drmanishnagpal@yahoo.com.
• Yusuke Oshima, MD, PhD, can be reached at Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka Suita, Osaka 565-0871, Japan; +81-66-8793456; fax: +81-66-8793458; e-mail: oshima@ ophthal.med.osaka-u.ac.jp. Dr. Oshima has no financial interests directly related to the products mentioned in the article but has received lecture fees and travel support from DORC.