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Surgeon: Oblique incision preferred in transconjunctival sutureless surgery
An oblique incision with 23- and 25-gauge systems helps maintain cannula stability in the eye.
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RIO GRANDE, Puerto Rico – Regardless of which vitrectomy system a retinal surgeon prefers, using an oblique incision instead of a straight incision will help the cannula remain in place, said Frank H.J. Koch, MD. He presented his observations using the II 4000 high-resolution gradient index solid rod endoscope on the Accurus (Alcon), Millennium (Bausch & Lomb), Associate 2500 (Dutch Ophthalmic) and Vit Enhancer (MID Labs) vitrectomy systems.
“All systems have to be handled differently to have an optimized profit from each of them,” he told attendees of the Masters of the American Society of Retina Specialists meeting.
Straight vitrectomy systems — such as the Accurus and Millennium — should be inserted obliquely, Dr. Koch said.
“If you insert the cannula a little obliquely, it will stay in the eye nicely; that’s something I’ve learned from using more and more of these different systems,” Dr. Koch said.
“Don’t forget to displace the conjunctiva,” he said, warning that neglecting to do so could increase the risk of infection.
Once the incision is made, the surgeon must determine how much port rotation is necessary to safely insert the ports into the eye wall, he said. He recommends the least amount of rotation possible but no more than 20° to 25°. The amount of rotation necessary depends on the system used, the rigidity of the eye wall and IOP.
In an interview, Dr. Koch told Ocular Surgery News that his experiences with the new micro-vitrectomy systems include more than 200 cases with 25-gauge systems and 20 cases with the 23-gauge system.
Surgeons should carefully select their cases suitable for sutureless small gauge vitrectomy, consider using oblique insertions of ports rather than straight, cleaning ports and entry sites, and should not apply external pressure during explantation to achieve successful and safe surgery, he said.
| Dr. Koch performs his technique for an oblique incision with a straight, 25-gauge vitrectomy system. According to Dr. Koch, even with a straight vitrectomy system, the incision should be created obliquely. Images: Koch FHJ | |
Incarceration difficult to avoid
Even when using an oblique incision, the amount of incarceration that will occur during insertion of the cannulas is an ever-present concern and is almost impossible to avoid, according to Dr. Koch.
“Using an oblique angle is advantageous,” he said. “But when does incarceration happen? How much do we need? How much can we tolerate?”
Once the surgeon pulls back the trocar, in most cases, vitreous will be incarcerated in the cannula, he said.
“The size of the cannula doesn’t matter,” he said. “Independent of the 25-gauge, 23- or 20-gauge systems, you will have a lot of vitreous that will be incarcerated into the cannula right at the moment when you pull out the trocar in each of the systems.”
He urged surgeons to clean the ports at the start and end of surgery.
“Use an oblique insertion, clean the entry port, and don’t apply external pressure to the eye during and after explantation,” he said.
Contraindications
In some cases, excessive bleeding occurs during or after explantation of the cannulas, Dr. Koch told Ocular Surgery News.
He pointed out that the sutureless architecture and especially the elongation of the wound in an oblique incision may increase the amount of bleeding in patients already prone to excessive bleeding. For this reason, the gold standard of 20-gauge may be the safer strategy in these patients instrumentation.
“In diabetic cases, it may cause more bleeding if you do the incision in an oblique fashion, because you pass through the eye wall in a longer distance, and the eye wall in a diabetic case is ready to bleed very easily whatever you do,” Dr. Koch explained.
With the high costs of small gauge vitrectomy systems, he said that situations like these might force ophthalmologists to choose which cases they can do if they are unable to afford the cost of maintaining both a small gauge system and a 20-gauge system.
“If you have enough money and you can keep [both systems] working and running, then you can select the cases,” he said.
“In short, different mini-gauge approaches afford different strategies to perform a successful pars plana vitrectomy,” he said.
For more information:
- Frank H.J. Koch, MD, can be reached at University Eye Clinic, Haus 7C Theodor Stern Kai 7, Frankfurt 60590, Germany; 49-69-6301-5649; fax: 49-69-6301-56; e-mail: fkoch7@compuserve.com.
- Michelle Dalton is an OSN Correspondent who covers all aspects of ophthalmology.
- Jared Schultz is an OSN Staff Writer who covers all aspects of ophthalmology. He focuses geographically on Europe and the Asia-Pacific region.