More Reason to SMILE in Large French Study

Small Incision Lenticule Extraction (SMILE) is an effective, stable, and safe procedure for treating myopia and myopic astigmatism, according to the results of a large-scale French study.

“Our study of a large cohort of eyes operated with SMILE confirmed it is an effective and safe refractive corneal procedure and provided a predictable and stable correction of myopia and myopic astigmatism with rapid recovery of vision quality postoperatively,” said David Donate MD.

While the results presented were slightly inferior to previous studies Dr Donate conducted, he said that was due to the inclusion of some initial patients treated with higher laser energy.

“The reduced energy settings of SMILE have definitely improved the outcomes and speed of postoperative visual recovery. We have also adapted our nomograms over time, which has improved the refractive results,” he added.

Dr Donate’s study presented the postoperative visual and optical results of 869 eyes treated at his clinic in Lyon, France.

“We had 2,744 eyes in total treated using SMILE. However, we removed 1,836 eyes lost to follow-up after one year and the first 5 eyes from the analysis because this represented the initial learning curve with SMILE. We also excluded 40 eyes with corrected distance visual acuity less than 20/20 and 20 eyes where the refractive target was different than the treatment plan. Another 4 eyes treated with a combination of corneal cross-linking (SMILE Xtra) were omitted,” he said.

The SMILE treatment parameters using the VisuMax® femtosecond laser (Carl Zeiss Meditec) included a lenticule diameter of 6.50 mm to 7.0 mm, cap thickness of 125 to 140 microns, spot distance of 4.0 to 4.50 microns, laser energy of 100 to 140 nanojoules, and a repetition rate of 500 kHz, Dr Donate said.

The analysis included visual and refractive outcomes, keratometry, pachymetry, topography, ocular surface, and contrast sensitivity testing. At one year follow-up, the mean uncorrected distance visual acuity was -0.06 logMAR with an efficiency index of 1.2. In terms of safety, 11% of eyes lost one line of vision at one year, and 97.5% of eyes attained 20/20 corrected distance visual acuity or better with a safety index of 1.6.

GOOD STABILITY OVER TIME

“The stability was also very good over time. We did see a slight tendency towards hyperopic shift because we deliberately chose this strategy based on the age of the patient,” Dr Donate explained.

In terms of astigmatism, 84.2% of eyes had less than 0.50 D of corneal astigmatism and 99.2% less than 1.0 D at one year. The mean contrast sensitivity showed rapid recovery one month after surgery to preoperative levels. Ocular surface index scores and higher-order aberrations also showed very little alteration from preoperative values to more than one year after surgery.

Intraoperative adverse events included 0.65% suction loss, compared to 4.68% in the FDA study for SMILE.
“Broken down, the figures were 0.11% for loss of suction in cases where the eye was eventually treated later by another modality such as PRK, LASIK, or ICL; 0.32% for loss of suction and immediate switch to another procedure; and 0.22% [for] loss of suction, but the treatment was successfully completed,” Dr Donate said.
Complications included one abscess, ectasia in 0.14%, and retreatments in 1.55% of cases.

Dr Donate noted that a comparison of the one-month results for those patients lost to follow-up after one year and those who were evaluated at one year found no statistically significant difference between the groups.

“This leads us to suppose that their eventual inclusion would not have had a significant influence on the overall results at one year,” he said.

Dr Donate presented this information at the French Implant and Refractive Surgery Association (SAFIR) Annual Meeting in Paris.

David Donate MD is an ophthalmologist in private practice in Lyon, France. david.donate@yahoo.fr