Perform LASIK on one eye before proceeding to next

London-A time-analysis study in a small group of patients showed that the optimum approach to LASIK when using the femtosecond laser (IntraLase, Advanced Medical Optics/IntraLase Corp.) to create the flap and an excimer laser to make the correction is to complete the entire procedure on one eye before starting the next.

Louis Probst, MD, showed that what he calls the "flap/zap, flap/zap" technique was slightly faster than the "flap/flap, zap/zap" approach in which both flaps are cut first. He spoke at the XXIV Congress of the European Society of Cataract and Refractive Surgeons in London.

Some surgeons have suggested that using the flap/zap approach would take too long because of patient rotations between lasers and necessary adjustments to the equipment. To address this question, Dr. Probst, who is regional medical director, TLC Vision, Chicago, conducted a study of 10 patients (20 eyes) randomly assigned into two groups of five each to undergo surgery with either the flap/flap or flap/zap method. Both groups had similar moderate levels of myopia, mean of –2.55 ± 1.53 D for the flap/flap group (group 1) and –2.73 ± 2.06 D for the flap/zap group (group 2).

"What I showed was that it actually took slightly less time to do the flap/laser, flap/laser technique as opposed to the flap/flap technique. It certainly didn't take more time," he said. For the flap/zap group, the average total treatment time was 7.46 minutes ± 29 seconds versus 8.23 minutes ± 31 seconds for the flap/flap group.

Because the study involved a slight difference in technique, no difference in visual acuity outcomes was expected, and Dr. Probst did not present visual acuity or safety data during his presentation.

The traditional method of performing LASIK with the femtosecond laser is to cut both flaps and then to perform the excimer laser treatment. This method developed in the days of lower-powered femtosecond lasers, when physicians often kept their femtosecond laser in a different room from their excimer laser, Dr. Probst explained. It was more convenient to use the same equipment on both eyes and then transfer the patient to the other room for the remainder of the procedure.

In addition, no adjustments of the laser bed were needed between flap creation for both eyes, and the opaque bubble layer (OBL) had time to become absorbed during the 10 to 15 minutes that patients waited between the femtosecond laser and excimer laser portions of surgery.

The flap/flap, zap/zap method has its drawbacks, however, Dr. Probst said. From the patient's perspective, the approach could be less than ideal because work is constantly switching from eye to eye and there is more stress at the start of the procedure.

Further, an extra drop of anesthetic is required, and safety concerns exist. Dr. Probst explained that if a problem were to occur during lifting of the right flap, the left eye already would have been touched and surgery would have to proceed.

"You're always in the middle of treatments of both eyes," he added. "There's always the risk that if there was some sort of challenge you didn't anticipate with lifting the flap to the right eye, then you'd be in an awkward situation because you've also created a flap in the left eye. This can be avoided by treating one eye at a time."

With a newer femtosecond laser such as the 60-kHz model, the flaps can be created very quickly, and there is less OBL. Thus, Dr. Probst decided it was an opportune time to study which technique was more efficient.

He noted that the flap/zap approach could be very efficient if the femtosecond laser and the excimer laser are in the same room, because the bed can be rotated between the two lasers.