The superior incision had an anticlockwise radial tear with a subsequent epithelial ingrowth. One year after surgery the ingrowth remained stationary without any effect on visual performance of the eye (Photograph by W. Sekundo)
10.1.5 Gas Breakthrough from One Laser Plane into the Other Plane
This absolutely exceptional complication was witnessed only once in a case referred for a second opinion. Indeed, it is almost impossible to recognize it during the scan and, if suspected, should be left alone and not dissected. The reason is lenticule which is too thin. Thus, a minimum lenticule central thickness of 50 μm is recommended. For further details, please see Chap. 7.
10.1.6 Forceful Dissection of the Wrong Plane Deeper than the Cleavage Plane Created by the Laser
This extremely rare complication was referred to us twice for a second opinion. In both cases the surgeon was novel to the procedure. This complication, in our view, is a result of a totally improper handling of the tissue. Little resistance to the dissection spatula is normal. However, if the surgeon encounters severe resistance reminiscent of lamellar keratoplasty, the procedure should be abandoned and no tissue removed from within the cornea. Otherwise a permanent damage will occur, relievable only by a lamellar anterior/inter-pocket/deep anterior lamellar keratoplasty.
10.2 Postoperative Complications After SMILE
10.2.1 Epithelial Ingrowth
Sometimes epithelial ingrowth can be observed, after SMILE. Unlike with LASIK, where ablation of the hinge can sometimes result in a path for the epithelium to encroach under the flap, in SMILE, it is usually an isolated nest of cells. They can either be left alone, if the nest is silent, or it can be scraped off by entering with an epithelial scraper from the original incision (Fig. 10.1).
10.2.2 Irregular Astigmatism Consequent to Decentration
Sometimes, if the docking procedure is not correct, it can result in decentration of the treatment and consequent irregular astigmatism and/or induction of aberrations, such as coma.
In our opinion, it is best to prevent this complication. Following the proper docking procedure is essential. We also find it useful to switch to infrared illumination for a brief period after docking (and before initiating the laser pass), to verify that the pupil dilates around the center of the contact glass.
In case decentration occurs, and it is visually significant, then it is best to perform a topography-guided excimer laser correction using PRK , keeping in mind the cap thickness.
10.2.3 Other Postoperative Complications
In some cases, a fine scarring is observed at the cap edge or the lenticule edge. However, this is outside the pupillary zone and is visually nonsignificant. Some patients, especially chronic contact lens users before the procedure, experience dry eyes after the procedure. We have also observed a few cases of a fine interface haze several months after the procedure. In the majority of cases it is not visually significant. Since the haze is sometimes related to ease of dissection, some surgeons increase and prolong their steroid regimen in cases of difficult dissection. We also observed a positive effect of fluoromethalone drops in cases of an increased haze 2 months after surgery. If a longer course of steroids is not desired, 1 % cyclosporin A (CSA) eye drops twice daily for several months helps to reverse the course.
Due to a geometrical mismatch between the undersurface of the cap and the stromal bed after lenticule removal, some microstriae, named “Bowman’s layer microdistortions” (BLMD), have been described particularly after highly myopic SMILE . In the majority of cases these microfolds are smoothed out by the epithelium as time goes by. If desired, an early intervention with pressurized flushing of the pocket can be attempted (B. Meyer, personal communication). Prior to such radical measures an anterior high-resolution OCT scan is of value. To prevent visually significant folds in the optical zone, one is advised to gently massage the cap centrifugally as suggested by Reinstein et al. .