Long-term outcomes favorable for femtosecond lenticule extraction

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Data from a series of 56 eyes examined at 5 years after femtosecond lenticule extraction (FLEx, Carl Zeiss Meditec) show good safety and long-term stability of the refractive and functional results.

By Cheryl Guttman Krader

Mumbai, India-Data from examined eyes with 5 years of follow-up support the conclusion that femtosecond lenticule extraction (FLEx, Carl Zeiss Meditec)-performed using a proprietary femtosecond laser (VisuMax, Carl Zeiss Meditec)-is a safe, effective, and predictable treatment for myopia and myopic astigmatism with good long-term stability, reported Rupal S. Shah, MD.

Dr. Shah said she first began performing the all-femtosecond laser procedure in August 2008, and had reported 1-month results for the first 85 eyes she treated. The long-term analysis she presented included data for two-thirds (56 eyes) of the eyes in her initial cohort.

A comparison of the outcomes achieved after 1 month and at 5 years showed that the long-term changes were in a positive direction towards higher efficacy and predictability.

“This study is a work in progress, but I believe that femtosecond lenticule extraction will truly lead to a paradigm shift in refractive surgery,” said Dr. Shah, clinical director, New Vision Laser Centers-Centre for Sight, Mumbai, India.

Exploring the study

Baseline data for the first 85 eyes showed they had a mean spherical equivalent of -3.90 D, with a mean sphere of -3.56 D (range -0.50 to -9) and mean cylinder of 0.69 D (range 0 to 3 D). The eyes that were available for follow-up at 5 years represented a slightly narrower range of correction with baseline sphere of up to -8 D and cylinder up to 2.25 D.

In all eyes, the extracted lenticule measured 6.0 mm in diameter, the overlying flap was 100 to 120 µm thick, and the residual stromal bed was >250 µm.

The target refraction was plano in all cases.

Findings from the original analyses showed that patients experienced a delay in visual recovery after the procedure. At 1 week, 47% of eyes had lost 2 or more lines from baseline best spectacle-corrected visual acuity (BSCVA).

Outcomes were better at 1 month when no eyes had lost more than 2 lines of BSCVA and BSCVA was unchanged or improved from baseline in 71% of eyes.

At 5 years, no eyes had lost 1 or more lines from their baseline BSCVA. Mean spherical equivalent at 1 year was about 0.05 D and showed remarkable stability over time.

“In fact, our data show continued improvement in refractive outcomes,” Dr. Shan said. “At 5 years, 100% of eyes were within 0.5 D of their plano target and all had uncorrected visual acuity of 20/25 or better.”

Comparing procedures

FLEx is one of two versions of the all-femtosecond laser refractive procedures known as Refractive Lenticule Extraction (ReLEx, Carl Zeiss Meditec). The laser is used to prepare both a corneal flap and the refractive lenticule. A newer version of ReLEx-known as Small Incision Lenticule Extraction (SMILE)-is a flapless procedure in which the lenticule is removed through a small, 2-3 mm corneal incision.

“Compared to LASIK, SMILE has advantages for the patient and the surgeon,” Dr. Shah said. “SMILE can be performed with only one laser, and it induces less dry eye, avoids concerns about flap displacement, and has the potential for better corneal biomechanical stability.”

Dr. Shah noted that it takes about 25 seconds for the femtosecond laser to complete the two passes that are needed to dissect the lenticule with the SMILE procedure. She added that the VisuMax laser has a curved corneal interface that does not cause a significant increase in IOP, therefore, patients are able to maintain fixation on the laser’s green blinking light during the entire procedure.

After the incision is opened, the anterior and posterior surfaces of the lenticule are easily separated from the overlying and underlying stroma using a blunt instrument.

The surgical microscope that is integrated within the femtosecond laser facilitates identification of the lenticule surfaces. However, a slit-lamp attachment is also available for use if needed.

Over the past 5 years, almost 4000 eyes have undergone a ReLEx procedure at a New Vision Laser Center, said Dr. Shah.

“ReLEx has definitely become the most premium refractive procedure in our practice,” she said.

Rupal S. Shah, MD

E: rupal@newvisionindia.com

Dr. Shah is a consultant to Carl Zeiss Meditec and receives fees for research and travel support.

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