Characteristics of disk halo size and its correlation with lenticule quality in small incision lenticule extraction for moderate to high myopia.

Purpose: To investigate changes in disk halo size after small incision lenticule extraction (SMILE) and the correlation between halo size and lenticule quality in moderate to high myopia.

Methods: Thirty eyes of 30 consecutive patients (mean age, 24.9 ± 4.5 years; mean spherical equivalent, -6.85 ± 1.18 D) undergoing SMILE were included in this prospective study. Lenticule surface quality was accessed with a scanning electron microscopy by a scoring system. Halo size was measured preoperatively and at 1, 3, and 6 months postoperatively. Multiple linear regression analysis was performed to explore associations between halo size and a range of factors, including lenticule quality.

Results: Disk halo size increased slightly at 1 month and then recovered continually from 3 to 6 months postoperatively, with no difference between halo size during the preoperative period and at 6 months postoperatively (P > 0.05). One month after SMILE, halo size (1 cd/m, 5 cd/m) was associated only with uncorrected distance visual acuity (P ≤ 0.004). A halo size of 5 cd/m at 3 months postoperatively correlated with the anterior surface quality of the lenticule (P = 0.046). At 6 months postoperatively, a halo size of 1 cd/m was associated only with the baseline, accounting for 11.9% of the variability (P = 0.041); no correlations were found for the halo size of 5 cd/m.

Conclusions: Disk halo size after SMILE was enlarged at an early stage postoperatively and subsequently declined to the baseline level during a 6-month follow-up. The quality of the lenticule surface influenced halo size changes in the early phase.