British Journal of Ophthalmology
Published online Nov. 18, 2020
Outcomes of small-incision lenticule extraction (SMILE) have been widely reported since its introduction in 2011 but have not been studied for different age groups. Primavera et al. reviewed patient data by age group (≤35 years and ≥40 years) to explore the potential relationship between age and surgical outcomes. The authors found that while SMILE was efficient, safe, and reasonably predictable in both age groups, younger patients had better results.
Patients in this study were required to have myopia (with or without mild or moderate astigmatism), mesopic pupil <7 mm, expected residual stromal bed under the cap of >250 μm, pre-op central corneal thickness >490 μm, and expected post-op mean keratometry >35 D.
The SMILE procedures were performed by one of two experienced surgeons during a three-year period. All eyes were evaluated preoperatively and were matched between groups by preoperative refractive spherical equivalent difference of ±0.25 D for each pair. Efficacy, safety, predictability, and astigmatic changes were assessed postoperatively at one and six months.
There were 51 eyes in each age group. By six months post-SMILE, both groups had gained lines of uncorrected as well as corrected distance visual acuity (CDVA), but the improvement in CDVA was significantly better in those ≤35 years of age (p = .005). Mean residual astigmatism was much worse in the older group (p = .019) despite a higher level of preoperative astigmatism in the younger group. The efficacy index for those older than 39 years was 0.86 at month 1 and 0.97 at month 6, compared with 0.97 and 1.07, respectively, for the younger patients (p = .003 at month 6). The safety index, calculated as loss of CDVA, for the older group was 0.93 at one month and 1.04 at six months, compared with 1.00 and 1.11, respectively, for the younger group (p = .008 at month 6).
Even though refractive outcomes were acceptable in older patients, this group had significantly lower indexes of efficacy and safety, poorer astigmatism reduction, and a tendency toward undercorrection. The authors suggested that the differences in outcomes may relate to the stiffening of the corneal stroma that occurs with aging.
The original article can be found here.