Femtosecond laser flap creation works for patients undergone previous RK

Take-home message: The first case series report of femtosecond laser flap creation for LASIK in eyes that have undergone radial keratotomy showed the technique was successful when novel settings were used. No significant intraoperative or postoperative complications were reported in the 27 eyes in the study, and uncorrected visual acuity improved significantly.

By Nancy Groves; Reviewed by Sloan W. Rush, MD

Amarillo, TX - Femtosecond-assisted LASIK in eyes that had previously undergone radial keratotomy (RK) was successful in all cases at a single-center study.

Although further studies are necessary, the technique for femtosecond laser flap creation appears to be safe and effective in these patients.

None of the 27 eyes (18 patients) had significant intraoperative or postoperative complications; uncorrected visual acuity improved significantly postoperatively (p < 0.0001); and remained stable through the final follow-up, 9 to 12 months later, said Sloan W. Rush, MD, private practice in Amarillo, TX, who performed the procedures

Many patients who underwent RK in the late 1980s and 1990s later developed hyperopic regression and have sought additional refractive treatment. While LASIK performed with mechanical microkeratome techniques and an excimer laser was often successful in post-RK patients, the development and growing use of femtosecond laser technology presented a new set of problems, Dr. Rush said.

This laser creates stromal tissue bridges that have to be cut with a spatula or other instrument, increasing the risk of reopening an old RK incision and traumatizing the flap.

Other problems that have been reported when using standard femtosecond laser setting have included loss of suction during treatment, postoperative interface inflammation, corneal haze, and loss of best spectacle-corrected visual acuity (BSCVA). Performing additional surgery has also been difficult in patients who had undergone both RK and cataract surgery.

Experimenting with settings

Since there was no indication on the femtosecond laser to guide refractive surgeons treating post-RK patients, Dr. Rush experimented with the settings, seeking a way to make a cleaner flap. He and colleagues at the Amarillo clinic adjusted spot sizes and increased the power so that the femtosecond laser would leave a minimal number of tissue bridges, in turn allowing the surgeon to more easily lift the flap.

He then retrospectively reviewed the charts of all post-RK patients who underwent femtosecond-assisted LASIK on the Wavelight FS200 femtosecond laser and the Allegretto Wave Eye-Q 400 Hz excimer laser (both Alcon Laboratories) from September 2013 through February 2014. The laser settings for flap creation were: bed cut energy, 1.4 µJ; bed cut spot separation, 6.0 µm; bed cut line separation, 6.0 µm; side cut energy, 0.8 µJ; side cut spot separation, 5.0 µm; and side cut line separation, 3.0 µm.

All of the flaps were lifted with no complications, there were no cases in which suction was lost, and no RK incisions were reopened. In addition, no subjects lost any lines of BSCVA.

“I believe this is the first report in which someone has described successfully using the femtosecond laser in the setting of previous RK,” Dr. Rush said. “In my center, now that we have figured out settings that work well, we permanently put our microkeratome on the shelf.”

Sloan W. Rush, MD

E: sloan.rush@paneye.com

This article was adapted from Dr. Rush’s presentation during the 2015 meeting of the American Society of Cataract and Refractive Surgery. Dr. Rush did not report any relevant financial relationships.