A Three-Year Observation of Corneal Backscatter After Small Incision Lenticule Extraction (SMILE)

To investigate changes in corneal backscatter after small incision lenticule extraction (SMILE).

One eye was randomly selected from 34 patients who underwent SMILE procedures. Corneal backscatter was analyzed using Scheimpflug technology before surgery and at postoperative 1 day, 1 week, 1 month, 3, 6, and 12 months, and 3 years. Three different corneal depths (the anterior 120 µm, the center, and the posterior 60 µm) and three concentric radial zones (0 to 2, 2 to 6, and 6 to 10 mm) were analyzed. Another 40 eyes of 40 patients who underwent femtosecond laser-assisted LASIK (FS-LASIK) were examined before surgery and at postoperative 1 day and 3 years as the control group.

At postoperative day 1, a significant increase in corneal backscatter was detected in the SMILE group compared to preoperative values in the central 0 to 6 mm zone of the anterior layer and the 0 to 2 mm zone of the central layer (all P < .01). This increase was higher than the increase in the FS-LASIK group in the central 0 to 6 mm zone of the anterior and central layers (all P < .01). No significant differences in corneal backscatter were detected between preoperative values and the 1-week, and 1-, 3-, 6-, and 12-month follow-up visits in the SMILE group (all P > .05). Moreover, a significant decrease in corneal backscatter was detected in the three zones of all three layers in the two groups at 3 years postoperatively compared to preoperative values (all P < .001) and no significant difference was found between the two groups (all P < .05).

Corneal backscatter peaks and declines to the baseline in the early period after SMILE and corneal transparency achieves an improvement within 3 years postoperatively. [J Refract Surg. 2017;33(6):377-382.].