Gaining Control With the New MIVS Technique
With a 25-gauge torpedo light, surgeons can use this bimanual approach in the most complicated cases.
BY ATHANASIOS NIKOLAKOPOULOS, MD
One of the most important aspects of vitreoretinal surgery is control. The more control the surgeon has over the necessary maneuvers, the fewer the difficulties and complications that can occur. While transconjunctival sutureless microincision vitrectomy surgery (MIVS) offers benefits for our patients, it can present challenges for surgeons. When physicians perform MIVS in the standard manner, complete peripheral vitrectomy and peripheral laser can be difficult, while sometimes illumination can be less than ideal. Furthermore, the surgeon has to grasp and cut tissue and perform other active maneuvers with only one hand. Removing membranes and traction on the retina are complicated maneuvers to perform with one hand and can lead to iatrogenic retinal breaks. Breaks and other serious complications also can occur when surgeons pull mobile detached retina too close to the cutting probe.
To overcome the limitations of single-handed MIVS so surgeons can perform a small-gauge procedure in all cases, my colleagues and I developed a technique that we call controlled bimanual vitrectomy (CO BI VI).
The main difference between CO BI VI and other surgical techniques is the use of a 25-g torpedo light source that is guided by an assistant. After infusion is placed into the eye at 20 mmHg of pressure, a 25-g needle is inserted at 12 o'clock. The conjunctiva is stretched in order to exchange the needle and the torpedo light, which is switched off to avoid glare. The light is secured to the patient's forehead with a Steri-Strip. A Steri-Strip made into a loop is attached around the light pipe at the entrance (Figure 1). This allows an assistant to move the light exactly where the surgeon needs it throughout the procedure. It gives the light mobility and ensures it will not accidentally come out of the eye.
Figure 1. A Steri-Strip made into a loop is attached around a 25-g torpedo-guided light pipe in a controlled bimanual vitrectomy (CO BI VI) procedure.
Another very important aspect of CO BI VI is the use of a vitreoretinal surgery system that uses vented gas forced infusion technology. This is crucial because we need to be able to safely work with high speeds and vacuum settings. Currently, I use the Alcon ACCURUS® vitrectomy system. I use high cutting speeds (usually more than 1000 cpm), high vacuum settings and higher-than-usual infusion pressures to take advantage of the vented gas forced infusion technology. I can control the pressure up to 120 mmHg, and the system allows fast and precise changes between static and dynamic infusion pressures.
Usually for 25-g surgery my settings are 60 mmHg and 20 mmHg. When I am using 600 mmHg of vacuum, the infusion is at 60 mmHg. When I stop the vitrectomy or lower the vacuum, I switch to 20 mmHg. I can take advantage of the different infusion settings for silicone oil injection or for air-fluid exchange when I use 70 mmHg for air infusion while removing subretinal fluid. At times, for 23-g silicone oil removal, the infusion is set up to 100 mmHg.
Benefits of CO BI VI
For retinal detachment surgery, I can perform scleral depression myself if I have an assistant guiding the torpedo light, and if I use high magnification and a wide-angle viewing system. This allows me to bring the periphery to the center for better access. I can perform peripheral vitrectomy and laser. Depressing the sclera myself, I also can stabilize the mobile detached retina and use the cutting probe to remove all traction from the tear sight while using sufficient vacuum. I can lift membranes with one hand to view the exact plane between the retina and the membrane and cut with the other hand, limiting the possibility of iatrogenic tears and cutting through the retina.
I have very good control and never lose sight of the tear. The technique is gentle to the eye. It is especially well-suited for small-gauge surgery because the instruments create less of a shadow than larger-gauge instruments and do not block my view as much. Furthermore, unlike single-handed surgery, where the light pipe often is used to facilitate maneuvers, in CO BI VI, the guided light is far away from the macula and light toxicity is not possible.
Following the removal of traction and a complete vitrectomy, including the peripheral vitreous, I infuse air at a pressure of 100 mmHg, while simultaneously removing the subretinal fluid with a soft-tipped flute needle. (In a trocar system, the infusion site can be changed to gain access for temporal vitrectomy.) When the retina is flat, I can apply laser. Using laser and not cryotherapy makes the procedure less traumatic with less inflammation.
At the end of the procedure, I set the infusion to 20 mmHg. When the eye is firm, I turn off the infusion and slowly remove one trocar, applying light pressure at the wound with a cotton tip. I do the same with the next trocar. After waiting a short time, I turn the infusion back on to 20 mmHg. If there is no wound leakage, I turn off the infusion and slowly remove the infusion line.
To date, we have performed more than 200 retinal detachment surgeries using CO BI VI. Our reattachment rate has been similar to 5–8 years ago with 20-g surgery (86%–88%), and the procedure takes approximately one-third of the time. We have had no cases of endophthalmitis.
The technique can be used in complicated cases. For lens dislocation, for example, we have the advantage of using 2 25-g forceps to hold and lift the lens back into the anterior chamber. Guided illumination and controlling infusion as needed for the various steps make this possible. I also have removed dropped lenses and nuclear fragments without using endophacofragmentation. In one hand, I use the 23-g vitrectomy probe on 600 mmHg of suction and a 1500 cpm rate. Then, I have the other hand to use another 23-g instrument. I guide the fragments to the port with one hand and use the other to mechanically crush, divide and conquer all the fragments. I also have used CO BI VI in cases of dropped lenses in the presence of proliferative vitreoretinopathy and in diabetes cases with traction detachment.
With CO BI VI, we can achieve the same results as 20-g surgery, but much more comfortably for our patients. Five of my patients who had CO BI VI in one eye and conventional retinal detachment surgery in the other could not believe they had the same kind of surgical treatment.
Athanasios Nikolakopoulos, MD, is chairman of the ophthalmology department at Papanikolaou Hospital in Thessaloniki, Greece.