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

Abstract 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 2 , 5 cd/m 2 ) was associated only with uncorrected distance visual acuity ( P ≤ 0.004). A halo size of 5 cd/m 2 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 2 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 2 . 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.