Candidate pool for refractive surgery
SMILE with CXL safe, effective, and predictable for eyes ectasia.
Sung Min Kim MD
Small-Incision Lenticule Extraction with accelerated corneal cross-linking (SMILE® Xtra) is a viable option for refractive correction in eyes at moderate risk for ectasia after corneal refractive surgery, according to a study presented by Sung Min Kim MD at the 2020 ASCRS Virtual Annual Meeting.
The investigation included 130 eyes of 65 patients operated on at the NUNEMISO Eye Centre, Seoul, Republic of Korea. All eyes had a cumulative score of 3 on the Randleman Ectasia Risk Score System and completed two years of follow-up. Eyes with keratoconus or that were keratoconus suspects were excluded.
The treatment protocol involved application of 0.25% riboflavin solution with a 90-second soak time followed by 60 seconds of UVA irradiation 30 mW/cm2 (total energy 1.8 J/cm2).
Compared with a group of eyes that underwent SMILE at the same centre, the SMILE Xtra cohort had poorer UCVA on the first postoperative day (mean decimal, 0.80 vs. 0.94). However, visual outcomes were similar in the two groups from one week to two years, and safety outcomes were comparable as well.
“Our study shows that the safety and predictability of SMILE are not affected by combined cross-linking and indicates that SMILE Xtra may be an effective and safe strategy for refractive surgery in moderate-risk patients,” said Dr Kim.
Preoperatively, the 130 eyes treated with SMILE Xtra had a mean sphere of -6.22D, mean cylinder of -1.59D and mean SEQ of -7.01D. At two years, 97.7% of eyes were within ±0.5D error range of SEQ. Other two-year SMILE Xtra results showed mean UCVA was 1.08 (vs 1.12 for SMILE), and the efficacy index was 1.13 (vs 1.16 for SMILE Xtra). At two years after SMILE Xtra, BCVA was the same or improved in 99.2% of eyes and decreased by one line in 0.8% of eyes. The safety index was 1.16 and endothelial cell count had not changed significantly from baseline.
Outcomes of SMILE Xtra were also analysed for four subgroups representing eyes with abnormal topography (n=36), low residual bed thickness (<300 microns; n=44), high refractive error (spherical equivalent >-9.5D or lenticule thickness >130µm; n=21) and thin preoperative central corneal thickness (<510µm; n=29).
There were no statistically significant differences between the subgroups in visual recovery or refractive change over two years, although there was a tendency towards poorer outcomes in the eyes with high refractive error. Endothelial cell count was also stable after SMILE Xtra in all subgroups.
Sung Min Kim: email@example.com