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Clinical Relevance: More than 6 million small-incision lenticule extraction (SMILE) procedures have been performed worldwide since 2011. Therefore, its long-term safety and efficacy should be investigated., Background: This study aimed to evaluate 10-year refractive outcomes, corneal stability, axial length, and wavefront aberrations in patients who underwent SMILE to correct myopia., Methods: Thirty two patients (32 eyes) who underwent SMILE-based myopic correction. Corrected distance visual acuity, uncorrected distance visual acuity, corneal stability, axial length, and wavefront aberrations were evaluated preoperatively and at 1 month and 1, 5, and 10 years postoperatively., Results: At 10 years postoperatively, the safety and efficacy indices for the patients included in this study were 1.19 ± 0.21 and 1.04 ± 0.27, respectively. For 26 (81%) and 30 eyes (94%), correction to within ±0.50 D and ±1.00 D of the target was achieved, respectively. Over the 10-year follow-up duration, a mean -0.32 ± 0.56 D regression was observed (-0.03 ± 0.06 D/year). Relative to baseline, horizontal and vertical comas significantly increased, as did the incidence of higher-order aberrations (all P  < 0.001), whereas axial length and corneal elevation remained stable during follow-up., Conclusion: These results indicate that the SMILE-based correction for myopia of up to -10 Dioptres is safe, effective, and stable, with relatively constant wavefront aberrations and corneal stability over time after treatment.

Purpose: To investigate the morphologic and histopathologic changes in allogeneic endokeratophakia using hyperopic lenticules derived from small-incision lenticule extraction (SMILE)., Methods: Six New Zealand rabbits (12 eyes) were included in this experiment and randomly and evenly divided into donor and recipient groups. The donor group underwent bilateral hyperopic SMILE surgery, and the concave lenticules were implanted into eyes in the recipient group. Corneal topography and anterior segment optical coherence tomography (OCT) examinations were performed at 1 day, 1 week, 1 month, and 5 months after surgery. All eyes were enucleated 5 months after surgery. Hematoxylin and eosin (HE) staining and transmission electron microscopy (TEM) were used to observe the corneal morphology in the recipient group., Results: No complications were observed, and the corneas remained transparent in the follow-up period. There was mild corneal edema within 1 week after surgery. Slit-lamp microscopy and OCT showed that the lenticules were gradually integrated with the surrounding corneal stroma. HE staining showed that the arrangement of corneal collagen was regular. The boundary between the lenticules and surrounding tissue could be identified with HE staining and TEM, and no inflammatory cells were found under TEM. The corneal Km values were significantly lower at 5 months postoperatively compared to preoperatively (P < 0.05)., Conclusions: This pilot study showed that allogeneic hyperopic SMILE lenticule endokeratophakia seems to be safe and feasible., Translational Relevance: Allogeneic hyperopic SMILE lenticule endokeratophakia may be applicable for the correction of corneal regression, ectasia, ultra-high myopia, or keratoconus.

Purpose: To investigate differences in the objective and subjective visual quality of patients with high myopia following implantable collamer lens V4c (ICL V4c) versus small incision lenticule extraction (SMILE) early postoperatively., Methods: This prospective analysis included 94 eyes of 57 patients (8 males) in the ICL V4c group (mean spherical equivalent (SE), -8.07 ± 1.03 dioptres (D)) and 103 eyes of 57 patients (13 males) in the SMILE group (mean SE, -7.85 ± 0.78 D). Refractive parameters and wavefront aberrations were recorded preoperatively and 6 months postoperatively. Subjective visual quality was scored with the Quality of Vision questionnaire, and operation satisfaction was evaluated 6 months postoperatively., Results: At 6 months postoperatively, the efficacy index was 1.17 ± 0.16 in the ICL and 1.09 ± 0.20 in the SMILE group; the safety index was 1.21 ± 0.18 in the ICL and 1.12 ± 0.16 in the SMILE group. A significant increase in total higher-order aberrations (HOAs) in both the ICL and SMILE groups was observed, but to a lesser degree in ICL (p < 0.05). In the ICL group, trefoil significantly increased (p < 0.05), whereas in the SMILE group, coma, trefoil and spherical aberration significantly increased (p < 0.05). Glare, haloes and blurred vision had the highest incidences after both types of surgery, and postoperative haloes were significantly more common following ICL; 96.1% of ICL-treated and 94.9% of SMILE-treated patients were satisfied with their visual outcomes., Conclusion: ICL V4c caused lower HOAs induction than SMILE. Despite the postoperative visual disturbances, both ICL and SMILE provided good efficacy, safety, predictability and high satisfaction in correcting high myopia., (© 2020 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Purpose: To investigate the optical transmittance and ultrastructure of small incision lenticule extraction (SMILE)-derived lenticules preserved via three different methods., Methods: A total of 90 lenticules obtained from myopic patients undergoing SMILE surgery were divided into control and experimental groups. Fresh lenticules served as the control. The preserved lenticules of the experimental group were randomly divided into three subgroups according to different storage conditions: anhydrous glycerol, silicone oil and allochroic silica gel groups. Optical transmittance was evaluated, histological changes were analysed by haematoxylin eosin (HE) staining, and collagen fibril densities and necrotic response were assessed via transmission electron microscopy (TEM) at 48 h, 14 days and 4 weeks., Results: After storage for 4 weeks, the mean percentage transmittance values in glycerol and silicone oil groups significantly decreased (P = 0.034 and P = 0.042, respectively), but the lenticules preserved in silica gel remained unchanged when compared with the control lenticules. In all the groups, HE staining results showed a regular arrangement of collagen fibers with a few keratocytes and several cavitation bubbles. TEM revealed that the fibril densities in the glycerol group (273.70 ± 31.42/μm 2 ) after 4 weeks were significant less than those in the other two groups (silicone oil, 335.20 ± 33.09/μm 2 ; silica gel, 371.80 ± 37.60/μm 2 ) and control group (340 ± 33.61/μm 2 ) (all P < 0.001). In each group, a few necrotic and apoptotic keratocytes were observed., Conclusions: All the three agents, namely glycerol, silicone oil and silica gel, could be used for lenticule preservation. Silica gel facilitates better maintenance of optical transmittance than the other two agents., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose: To investigate morphological changes in the cornea and the implanted lenticule in patients with corneal ectasia after laser in situ keratomileusis (LASIK) and implantation using a lenticule from small incision lenticule extraction (SMILE)., Methods: Eight eyes of 8 patients with ectasia after LASIK from 2015 to 2018 at the Eye and ENT Hospital of Fudan Unversity were analyzed. For recipient eyes, lenticules were transferred with a mean cryopreserved time of 20 ± 21 days extracted from SMILE donors to the exposed stromal bed after lifting the flaps and the flap was repositioned. Uncorrected and corrected distance visual acuity, manifest refraction, and corneal topography were performed. Patients were followed up for 3 years. Changes in lenticules and recipient corneas were analyzed using in vivo confocal microscopy., Results: Activated keratocytes in the anterior and posterior stroma were observed near the lenticule at the first 6 months. Elongated, deformed keratocyte nuclei were found in the implanted lenticules in postoperative year 1. The anterior and posterior interfaces showed an absence or decrease of keratocytes and the presence of small particles of varying brightness. Nerve fibers in the implanted lenticules were detected in one case. No obvious difference was detected between cryopreserved and fresh lenticules., Conclusions: The preliminary findings suggest that recipient keratocytes repopulate the lenticules and the keratocytes in lenticules gradually return to their normal morphology. [J Refract Surg. 2020;36(11):714-722.]., (Copyright 2020, SLACK Incorporated.)

Objective: To evaluate the features of corneal nerve destruction after small incision lenticule extraction (SMILE) with different cap thicknesses (100 and 120 μm)., Methods: Nine consecutive patients (18 eyes) received SMILE with a 120-μm cap thickness and nine patients (18 eyes) with a 100-μm cap thickness were recruited. Confocal microscopy was used to evaluate the density and microscopic morphological changes of central corneal subbasal nerves preoperatively and at postoperative week 1., Results: The postoperative corneal subbasal nerve densities decreased significantly in both 120 μm and 100 μm groups. No statistical difference was detected in reduction of subbasal nerve density between two groups (P = 0.299). The number of subbasal nerve fibers significantly decreased in both groups. The reductions were not significantly different between two groups (P = 0.293)., Conclusions: Using a 120-μm cap thickness during SMILE preserves no more central corneal subbasal nerve fibers compared to a 100-μm cap thickness.

Purpose: To determine the incidence, management, outcomes, and risk factors of suction loss during femtosecond laser small incision lenticule extraction (SMILE) for the treatment of myopia and myopic astigmatism., Methods: The study reviewed 12,057 consecutive eyes treated with SMILE. Eyes that developed suction loss (study group) or underwent uneventful SMILE (control group) were analyzed. Corneal topography, manifest refractions, and measurements of uncorrected (UDVA) and corrected (CDVA) distance visual acuities were evaluated preoperatively and postoperatively after 1 day and 12 months. Risk factors were determined for suction loss development., Results: Twenty-seven of 12,057 eyes (0.22%) were enrolled in the study group and 50 eyes in the control group. Suction loss occurred in 14 eyes during the cutting of the refractive lenticule, 7 eyes during the cutting of the cap, and 6 eyes during the creation of the cap small incision. There was no statistically significant difference between the two groups in logMAR UDVA (P = .52) or CDVA (P = .59). A novel method of increasing cap thickness was applied to 8 eyes when suction loss occurred after more than 10% of the lenticule was cut. The eye being operated on first (the right eye) (P = .02) and a thinner lenticule (P = .006) were associated with a significantly higher risk of developing suction loss., Conclusions: The incidence of suction loss was low. The novel method achieved visual and refractive outcomes as favorable as those of uneventful SMILE procedures. The first eye that was operated on had a higher risk for the development of suction loss. [J Refract Surg. 2020;36(5):308-316.]., (Copyright 2020, SLACK Incorporated.)

Purpose: To investigate the predictability of the achieved lenticule thickness in small incision lenticule extraction (SMILE) for the correction of myopia., Methods: In this prospective study, a total of 80 eyes of 45 patients who underwent the SMILE procedure were included. A Scheimpflug camera was used to measure the preoperative and postoperative corneal topography. Achieved lenticule thicknesses at the pupil center and corneal vertex were calculated by subtracting the postoperative corneal thickness at the pupil center and corneal vertex from preoperative corresponding values. Predictability between the achieved and VisuMax readout at different locations (the pupil center and corneal vertex) and postoperative visits (postoperative day 1 and 6 months) were evaluated using a general linear model., Results: Achieved lenticule thickness at the pupil center and corneal vertex showed good correlation at both postoperative day 1 (pupil center: r=0.914, corneal vertex: r=0.903) and 6 months (pupil center: r=0.886, corneal vertex: r=0.866). The achieved lenticule thickness at postoperative day 1 was 8.5-μm thinner at the pupil center and 9.6-μm thinner at the corneal vertex than the VisuMax readout., Conclusions: This study suggests that the predictability between the achieved and VisuMax readout is favorable. The lenticule thickness at the pupil center is closer to the VisuMax readout than corneal vertex.

Background: To evaluate the feasibility and efficacy of small incision lenticule extraction (SMILE) in the treatment of myopia with corneal opacity., Methods: To evaluate the treatment of myopia with corneal opacity, 9 patients (4 males, 5 females) who underwent SMILE were enrolled in this prospective clinical study. One eye of each patient was treated. The results of laser scanning and lenticule extraction were observed during the surgery, and the surgical videos were again reviewed after surgery. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and spherical equivalence (SE) were noted at 1 month after surgery. The depth and density of the corneal opacities were measured by anterior segment optical coherence tomography (AS-OCT) and the Pentacam anterior eye segment analyzer., Results: All procedures were uneventful and no intraoperative complications were observed. At 1 month after surgery, the UDVA of all patients was 20/25 or better and no patients lost Snellen lines. The mean safety and efficacy indexes were 1.10 ± 0.24 and 1.08 ± 0.16, respectively, at 1 month postoperatively. The mean postoperative spherical equivalent was 0.27 ± 0.23 diopter (D). All eyes were within ±0.75 D and 8 eyes (88.9%) were within ±0.50 D. There was no eccentric corneal topography or abnormal morphology in the corneal caps. The corneal opacities of all patients were within the optical zone. The mean preoperative depths in the deepest areas of corneal opacity were 152 ± 38 μm (range: 86-217 μm); at 1 month after surgery (P < .01), they were 117 ± 28 μm (range: 86-189 μm). The preoperative maximum density of corneal opacity was 48.5 ± 20.7 (range: 20.4 to 85.8); at 1 month after surgery (P > .05), it was 49.8 ± 26.7 (range: 19.8 to 82.5) at 1 month after surgery., Conclusion: Patients with corneal opacity can be successfully treated with the SMILE operation. The short-term outcome was good, however the long-term results need further study., Trial Registration: The trial registration number: ChiCTR-ONRC-13003114 , Date of Last Refreshed on: 2016-01-27, Date of registration on 2013-03-17(retrospectively registered).

Purpose: To investigate the changes of posterior corneal elevation after small incision lenticule extraction (SMILE) for moderate and high myopia., Methods: In this prospective study, fifty consecutive eyes of thirty patients (10 male, 20 female) who underwent SMILE for myopia and myopic astigmatism were included. Eyes were divided in two groups based on the preoperative spherical equivalent refraction: high myopia group (32 eyes, range -6.25D to -10.00D) and moderate myopia group (18 eyes, range -3.00D to -6.00D). Posterior corneal surfaces were measured by a Scheimpflug camera (Pentacam, Oculus Germany) preoperatively and 1 month, 3 months, 6 months and 12 months postoperatively. Posterior central elevation (PCE) and posterior mean elevation (PME) at 17 predetermined points in the central-4mm area above the best-fit sphere were analyzed., Results: No significant difference in the amount of posterior corneal elevation changes in the high myopia group was noted over time (P = 0.23 and P = 0.94 for PCE and PME, respectively). Similarly, the changes in the moderate myopia group before and after SMILE were not significant either (P = 0.34 and P = 0.40 for PCE and PME). A statistically significant correlation was found between the residual bed thickness and the shift of the PCE in the high myopia group at 12 months postoperatively (r = 0.53, P = 0.01)., Conclusions: The results of this study suggest that the posterior corneal surface remain stable within one year after SMILE for both moderate and high myopia. The changes of PCE correlate to the residual bed thickness for high myopia. Long-term changes of posterior corneal surface need further investigation.

Purpose: To evaluate the surface characteristics of lenticules extracted by continuous curvilinear lenticulerrhexis (CCL) in small incision lenticule extraction., Methods: Twelve eyes treated with small incision lenticule extraction were included in the study and divided into two groups: the CCL and traditional groups. The extracted lenticules were examined with scanning electron microscopy. Both the anterior and the posterior surfaces of the lenticules were accessed. A scoring system was used to evaluate surface characteristics of the lenticules with a full mark of 16., Results: All of the lenticules in the CCL group exhibited smoothness and regularity on both sides and received scores of 14 or 15. The average score of anterior surfaces was 14.83 ± 0.41 for the CCL group and 14.00 ± 2.45 for the traditional group. The average score for the posterior surfaces was 14.50 ± 0.55 for the CCL group and 14.83 ± 0.41 for the traditional group., Conclusions: The surfaces of lenticules extracted by the CCL technique in small incision lenticule extraction are of good quality., (Copyright 2015, SLACK Incorporated.)

Purpose: Lenticule implantation can be used to correct vision problems. However, it is significantly restrained by the sources of autologous lenticules. The aim of the present study was to investigate the feasibility and effects of femtosecond laser-assisted corneal small incision allogenic intrastromal lenticule implantation (AILI) in monkeys., Methods: Six healthy adult monkeys were included in this study. Femtosecond lenticule extraction (-4.0 diopter [D] correction, 5.0-mm optical zone) was performed in one eye of two monkeys and both eyes of one monkey. Each extracted refractive lenticule was allogenically transplanted into a femtosecond laser-created corneal stromal pocket in one eye of the other two monkeys and one monkey's both eyes. Pre- and postoperative (1 or 3 days, 1 month, and 6 months) slit lamp microscopy, corneal topography, anterior segment optical coherence tomography, and in vivo confocal microscopy were performed., Results: Corneal edema occurred in the early postoperative days with a large number of hyperreflective particles around the borders. Corneal tissue edema gradually decreased. Nerve fiber regeneration could be detected in the lenticule layer at 6 months. Overall, 3.27 ± 1.2 D corneal power was increased at 6 months, accounting for 82% of the intended correction. At the same time point, corneal stroma was 69 ± 11 μm thicker than preoperative ones and was roughly equal to the maximum thickness of implanted lenticules. No significant complications were observed., Conclusions: The AILI technique seems to be feasible and safe for increasing corneal stromal thickness and changing corneal refractive power, which may provide a useful method for treatment of keratoectasia, presbyopia, and hyperopia.

Purpose: To measure decentration following femtosecond laser small incision lenticule extraction (SMILE) for the correction of myopia and myopic astigmatism in the early learning curve, and to investigate its impact on visual quality., Methods: A total of 55 consecutive patients (100 eyes) who underwent the SMILE procedure were included. Decentration was measured using a Scheimpflug camera 6 months after surgery. Uncorrected and corrected distance visual acuity (UDVA, CDVA), manifest refraction, and wavefront errors were also measured. Associations between decentration and the preoperative spherical equivalent were analyzed, as well as the associations between decentration and wavefront aberrations., Results: Regarding efficacy and safety, 40 eyes (40%) had an unchanged CDVA; 32 eyes (32%) gained one line; and 11 eyes (11%) gained two lines. Fifteen eyes (15%) lost one line of CDVA, and two eyes (2%) lost two lines. Ninety-nine of the treated eyes (99%) had a postoperative UDVA better than 1.0, and 100 eyes (100%) had a UDVA better than 0.8. The mean decentered displacement was 0.17 ± 0.09 mm. The decentered displacement of all treated eyes (100%) was within 0.50 mm; 70 eyes (70%) were within 0.20 mm; and 90 eyes (90%) were within 0.30 mm. The vertical coma showed the greatest increase in magnitude. The magnitude of horizontal decentration was found to be associated with an induced horizontal coma., Conclusions: This study suggests that, although mild decentration occurred in the early learning curve, good visual outcomes were achieved after the SMILE surgery. Special efforts to minimize induced vertical coma are necessary., (Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.)

Background: The novel Femtosecond lenticule extraction (FLEx) procedure has been considered safe, predictable, and effective in treating myopia and myopic astigmatism, with few complications. However, an enhancement procedure after FLEx may be required in some cases, but has not been reported in detail., Case Presentation: A 24-year-old woman who had undergone bilateral FLEx with the VisuMax femtosecond laser treatment for myopic astigmatism complained of double vision in her left eye after the operation. The manifest refraction was -0.50/-1.25 × 180°. The corneal topography showed a central-inferior steepened zone. The ocular wavefront measurements displayed a high value of total aberrations as well as coma. She was scheduled for an enhancement procedure and it was performed by relifting the primary FLEx flap in the left eye four months later. Ablation was made with the Mel-80 excimer laser. After retreatment, the corresponding aberrations were diminished and the corneal topography turned flattened. Her symptom resolved completely with good visual outcomes., Conclusion: This first detailed case report demonstrates the feasibility and efficacy of enhancement after FLEx for visual symptomatic eye after myopia correction. An analysis of more cases would be necessary to determine a more definite profile.

Purpose: To investigate the differences in corneal deformation parameters after femtosecond laser small incision lenticule extraction (SMILE), laser-assisted subepithelial keratomileusis (LASEK), and femtosecond laser-assisted LASIK (FS-LASIK)., Methods: In this retrospective study, 17 eyes of 17 patients after SMILE, 18 eyes of 18 patients after LASEK, and 17 eyes of 17 patients after FS-LASIK were included. Corneal deformation parameters were measured with the CorVis ST tonometer (Oculus Optikgeräte GmbH, Wetzlar, Germany) 3 months postoperatively., Results: The mean value of deformation amplitude of the FS-LASIK group was significantly higher than that of the LASEK group (P = .022). The mean value of applanation time (applanation 1) of the LASEK group was significantly higher than that of the FS-LASIK group (P = .038). No significant difference was detected in the mean values of deformation amplitude and applanation time (applanation 1) (P > .05) between the LASEK and SMILE groups or between the SMILE and FS-LASIK groups. Multiple linear regression model analysis revealed that after adjustment for age and preoperative central corneal thickness and manifest refraction spherical equivalent, the significance of the difference in the mean values of applanation time (applanation 1) and deformation amplitude between the LASEK and FS-LASIK groups were P = .084 and .059, respectively. In all three groups, the values of applanation 1 negatively correlated to those of applanation time (applanation 2) (SMILE: r = −0.577, P = .015; LASEK: r = −0.833, P < .001; FS-LASIK: r = −0.516, P = .034) and deformation amplitude (SMILE: r = −0. 556, P = .021; LASEK: r = −0.877, P < .001; FS-LASIK: r = −0.509, P = .037)., Conclusions: Applanation time (applanation 1) and deformation amplitude (as measured with the CorVis ST tonometer) may be helpful in assessing corneal biomechanical changes after corneal refractive surgery. The relations between these parameters should be discussed in further studies.

Purpose: To investigate objective optical quality and changes in light scatter after femtosecond laser small incision lenticule extraction (SMILE) for moderate to high myopia correction., Methods: Prospective clinical study of 66 eyes of 66 patients (23 males, 43 females) with a mean age of 28.67 ± 6.62 years, mean spherical refraction of -6.06 ± 1.57 diopters, and mean cylindrical refraction of -0.68 ± 0.46 diopters. Every patient had a 3-month follow-up after a standard SMILE procedure. An optical quality analysis system was used to measure modulation transfer function cutoff frequency (MTFcutoff), Strehl2D ratio, and objective scatter index (OSI)., Results: At 3 months postoperatively, mean spherical equivalent was 0.03 ± 0.24 diopters and corrected distance visual acuities of all patients were equal to or better than preoperative values, with a mean safety index of 1.12 ± 0.17 (range: 0.80 to 1.50) and mean efficacy index of 1.18 ± 0.21 (range: 0.80 to 1.50). Mean OSI increased from 0.75 preoperatively to 1.09 at 20 days postoperatively (P < .05), and gradually declined to 0.94 at 40 days and 0.82 at 3 months postoperatively (P > .05). MTFcutoff and Strehl2D ratio did not change significantly compared with preoperative values (P > .05). Multiple linear regression analysis revealed that preoperative OSI was significantly correlated with optical quality at 3 months. Patients with less preoperative OSI tended to acquire higher MTFcutoff (b = -8.61) and lower OSI (b = 0.65) (P < .05)., Conclusions: SMILE had little impact on retinal image quality after myopia correction. Postoperative OSI showed a temporary increase and then returned to normal., (Copyright 2014, SLACK Incorporated.)

Purpose: To investigate the morphology of corneal caps in femtosecond laser small incision lenticule extraction (SMILE) and its relation to the refractive outcomes., Methods: A prospective study of fifty-four corneal caps created with VisuMax femtosecond laser were examined using an Fourier-domain optical coherence tomography at 1 day, 1 week, 1 month and 6 months after SMILE. The cap thickness at nine points on each of the four meridians (0°, 45°, 90°, 135°) and the diameter were measured. Cap morphology, changes over time and its correlation with refractive outcomes were assessed., Results: The mean achieved central cap thickness were (108.74±5.06) µm at 6 months and (107.32±4.81 ) µm at 1 month postoperatively, significantly thinner than that at 1 day (110.81±7.95) µm and 1 week (109.58±7.48 ) µm (P<0.05). The mean diameter on 0° meridian was (7.61±0.07) mm, significantly larger than that on 90° meridian (7.57±0.06) mm (P = 0.001). Cap morphology showed good regularity, except that the differences of points in two pairs were significant at 1 day postoperatively. The uniformity was consistent over time and the central cap thickness was thinner than those in the paracentral and peripheral areas. The refractive outcomes stabilized within 1 month. Uncorrected distance visual acuity (UDVA) was correlated to the central cap thickness at 1 day and 1 week (both rs  = 0.33, p<0.05). The uniformity index was correlated with UDVA (rs  = 0.34, p<0.05) and corrected distance visual acuity (rs  = 0.32, p<0.05) at 1 week postoperatively., Conclusions: Corneal caps of SMILE are predictable with good reproducibility, regularity and uniformity. Cap morphology might have a mild effect on refractive outcomes in the early stage. Further study should focus on the impact on the visual quality.