Vision system enables easy transition to coaxial MICS

September 1, 2008

A prospective evaluation of the first 50 cases of coaxial microincision cataract surgery performed with a vision enhancement system (Stellaris, Bausch & Lomb) shows that the platform facilitates adoption of this new surgical technique and allows surgery to be performed with higher levels of vacuum, less dependence on ultrasound, and excellent anterior chamber stability.

Key Points

Chicago-Initial experience using a vision enhancement system (Stellaris, Bausch & Lomb) to perform coaxial microincision cataract surgery (C-MICS) shows that this platform enables safe and efficient phacoemulsification for surgeons who are transitioning to this new microincision technique, said Dominique Monnet, MD, at the annual meeting of the American Society of Cataract and Refractive Surgery.

Dr. Monnet and Antoine Brézin, MD, collected prospective data for the first 50 C-MICS cases they performed using the system with its optional high-vacuum, surge-resistant tubing (StableChamber). Procedures were performed through a 1.8-mm clear corneal incision with patients under topical anesthesia. One surgeon used a stop-and-chop technique and the other performed divide-and-conquer technique. Neither had experience with C-MICS. Eyes received an IOL (MI60 Akreos, Bausch & Lomb) through an unenlarged incision.

The study showed a safe and minimal learning curve for C-MICS. The platform's fluidics allowed higher vacuum levels with excellent anterior chamber stability and less dependence on ultrasound.

"Although there was some difficulty introducing the handpiece while keeping the sleeve well-positioned around the tip and not outside the eye, the stability of the anterior chamber, followability, and efficiency were particularly impressive," Dr. Monnet said.

In addition to the use of the new phaco system, two other changes were introduced in the surgical technique. These changes involved use of a trapezoidal knife and a new capsulorhexis forceps.

Dr. Monnet reported that no intraoperative complications were encountered. Incision competency was considered excellent with no leakage after stromal hydration or evidence of thermal corneal thermal injury.

There was a learning curve for implanting the lens through the 1.8-mm incision, but it was easily surmounted.

"The countertraction technique is helpful for inserting the IOL through this small incision, but toward the end of this study we found it was not required," Dr. Monnet said.

In two eyes, the lens became caught in the incision during implantation, but it still could be inserted with the forceps. One eye developed an inflammatory reaction at 1 month after surgery, accompanied by retraction of the capsular bag. A haptic outside of the bag was noted as the cause. The IOL was replaced in good position in a secondary procedure, and the patient recovered his initial postop visual acuity of 20/25.

Parameters

The surgeons also recorded the phaco parameters during each case and reviewed changes between the first five cases and last 10 that were made to optimize the surgery. The results showed an increase in vacuum during both sculpting (100 to 150 mm Hg) and lens removal (400 to 550 mm Hg), with a decrease in ultrasound percent during both phases (25% to 20%) and a shift from pulse/burst to continuous mode. Bottle height was raised slightly during lens removal (110 to 120 cm), and no change was made to the irrigation/aspiration parameters.

"Using this machine with its [surge]-resistant tubing, chamber stability is excellent," Dr. Monnet said. "This allowed us to increase vacuum and use ultrasound in a continuous mode that appeared more efficient and allowed a decrease in mean power."

The effect of these changes on optimizing surgery was demonstrated through a graph plotting effective phaco time (EPT) for each case performed by each surgeon. The results showed a progressive decrease in EPT over the course of the series, with statistically significant reductions between the first and last cases.

"Interestingly, EPT for the surgeon using the divide-and-conquer technique was greater than for the surgeon performing the stop-and-chop [technique]," Dr. Monnet concluded.