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Purpose: The aim of this study was to evaluate the safety, efficacy, and predictability of lenticule intrastromal keratoplasty (LIKE) for the correction of iatrogenic high hyperopia., Methods: Three patients (4 eyes) were referred to our department because of overcorrection of myopia induced by femtosecond laser-assisted in situ keratomileusis. All eyes exhibited hyperopia (between +4.00 and +8.00 D) and thin corneas ranging from 307 to 378 μm. Because of the regression of the use of laser ablation to correct high hyperopia and thin corneas, we initially adopted LIKE to correct iatrogenic high hyperopia in all 4 eyes. The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, corneal topography, and anterior segment optical coherence tomography findings were recorded during each follow-up evaluation., Results: No postoperative complications, such as interface haze and opacification, were observed in the 4 eyes during each follow-up evaluation, with an average follow-up of 9.50 months. All eyes had significantly improved UDVA postoperatively. A total of 3 eyes achieved an UDVA of 20/25 or better while the other 1 eye had an UDVA of 20/40 postoperatively. In addition, 2 of the 4 eyes had a postoperative UDVA equal to or better than preoperative CDVA. No eyes lost any CDVA lines. All 4 eyes were within ±0.50 D of the spherical power (intended target of 0). The central corneal thickness and curvature of the anterior corneal surface in all 4 eyes increased postoperatively. Anterior segment optical coherence tomography revealed that the lenticule was transparent, with no wrinkles or offsets, during each follow-up evaluation., Conclusions: LIKE for the correction of iatrogenic hyperopia has good efficacy and safety. Although an extremely thin cornea after overcorrection may not be suitable for hyperopic laser enhancement, LIKE is a good choice because of its good predictability and ability to restore the normal corneal structure., Competing Interests: The authors have no funding or conflicts of interest to disclose., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

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 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.)

Background: We aimed to compare the intraocular pressure (IOP) measurements by a dynamic Scheimpflug analyzer (Corvis ST), a non-contact tonometer, and an ocular response analyzer after hyperopic small-incision lenticule extraction (SMILE)., Methods: Thirteen patients who underwent hyperopic SMILE in one eye were enrolled prospectively. IOP and corneal biomechanical parameters were measured preoperatively and at 1 week, 1 month, and 3 months postoperatively with a non-contact tonometer (IOP NCT ), Corvis ST (biomechanical corrected IOP [bIOP]), and ocular response analyzer (Goldmann-correlated intraocular pressure [IOPg] and cornea compensated IOP [IOPcc]). A linear mixed model was used to compare the IOPs and biomechanical values among methods at each time point., Results: IOP NCT , IOPg, and IOPcc dropped significantly after surgery, with the amplitude being 3.15 ± 0.48 mmHg, 5.49 ± 0.94 mmHg, and 4.34 ± 0.97 mmHg, respectively, at the last follow-up visit. IOP NCT decreased by 0.11 ± 0.06 mmHg per μm of excised central corneal thickness. bIOP did not change significantly after surgery. Preoperatively, no difference was found among the four measurements (P > 0.05). Postoperatively, IOP NCT and bIOP were higher than IOPg and IOPcc. bIOP was independent of cornea thickness at last follow-up visit, whereas it correlated significantly with corneal biomechanics similar to the other three IOP values., Conclusion: bIOP is a relative accurate measure of IOP after hyperopic SMILE.

Purpose: The aim of this study was to compare visual outcomes after small incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for high myopia., Methods: In this prospective, comparative study, a total of 52 eyes of 34 consecutive highly myopic patients with spherical equivalent within the range of -8.00 to -10.00 diopters were recruited. Twenty-three eyes of 16 patients were in the FS-LASIK group and 29 eyes of 18 patients were in the SMILE group. Visual outcomes and wavefront aberrations were analyzed preoperatively and 6 months postoperatively., Results: At the postoperative 6-month visit, 96.6% in the SMILE group and 91.3% in the FS-LASIK group achieved unchanged or better corrected distance visual acuity (CDVA). As for uncorrected distance visual acuity (UDVA), 96.6% in the SMILE group and 95.7% in the FS-LASIK group achieved UDVA of 20/20 or better. As for wavefront aberrations, high-order aberrations (HOAs) and spherical aberrations increased significantly after surgery in both groups relative to corresponding preoperative values (p < 0.001), and vertical coma increased after SMILE (p < 0.001). No statistically significant differences in changes of HOAs (p =0.90), spherical aberrations (p = 0.07), horizontal coma (p = 0.56), coma (p =0.08), horizontal trefoil (p =0.19), vertical trefoil (p = 0.90), and trefoil (p = 0.45) were detected between the 2 groups, except for vertical coma (p < 0.01)., Conclusions: SMILE is as effective as FS-LASIK in correcting high myopia, but attention should be paid to the induction of vertical coma in highly myopic patients following a SMILE procedure., (© 2019 S. Karger AG, Basel.)

Purpose: To compare visual outcomes and aberration outcomes in small incision lenticule extraction (SMILE) versus femtosecond laser LASIK (FS-LASIK)., Methods: This prospective, comparative, nonrandomized clinical study included 68 eyes of 37 patients receiving SMILE and 55 eyes of 30 patients receiving FS-LASIK between December 2011 and January 2013 at the Fudan University Eye and ENT Hospital (Shanghai, People's Republic of China). Patients were followed up at 3, 6 months and 5 years after surgery. Main outcome measurements included uncorrected (UDVA) and corrected (CDVA) distance visual acuity, manifest refraction, central corneal thickness (CCT), total corneal refractive power (TCRP) and wavefront aberrations., Results: About 98% (49/50) of treated eyes in the SMILE group and 95% (39/41) in the FS-LASIK group had a postoperative logMAR UDVA of 0 or better. Spherical equivalent (SE) after 5 years was -0.01 ± 0.35 D in the SMILE group and -0.23 ± 0.41 D in the FS-LASIK group. A regression of -0.02 ± 0.39 D in the SMILE group and -0.12 ± 0.32 D in the FS-LASIK group was observed between 6 months and 5 years postoperative time-points. TCRP increased by 0.39 ± 0.38 D in the SMILE group and 0.45 ± 0.49 D in the FS-LASIK group between 6-month and 5-year time-points. However, no statistically significant difference was found between the SMILE and FS-LASIK groups in terms of ∆SE, ∆CCT and ∆TCRP between 6 months and 5 years postoperative time-points., Conclusion: Myopic regression was observed in terms of TCRP but not in subjective refraction. No statistically significant difference in stability was found between SMILE and FS-LASIK., (© 2019 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Background: To report a first case of lenticule addition and corneal cross-linking for post-LASIK ectasia with associated corneal thinning., Case Presentation: Lenticule addition followed by corneal cross-linking was performed on the left eye of a patient with post-LASIK ectasia. Postoperatively, the corneal power and elevation were stable with a remarkable improvement in corneal thickness, and the lenticule had merged with the adjacent corneal stroma at 30 months follow-up. The patient's corrected distance visual acuity gained two lines., Conclusions: This case provides a potential treatment option for patients with keratectasia and keratoconus in association with thin corneal thickness (less than 400 μm) and may provide the benefit of delaying or avoiding the need for keratoplasty, which has its own associated complications and is limited by the availability of donor corneas.

Background: To report a first case of late-onset diffuse lamellar keratitis (DLK) occurring 4 years after femtosecond laser-assisted small incision lenticule extraction (SMILE)., Case Presentation: A 41-year-old man who underwent SMILE 4 years prior developed DLK in the right eye 1 day after he was struck in the eye by a finger while playing with his son. Slim-lamp microscopy and anterior segment optical coherence tomography (AS-OCT) were used to evaluate the cornea of the right eye. Slit-lamp examination of the right eye revealed epithelial exfoliation and stage 3 DLK with diffuse, dot-like, granular haze in the interface between the cap and stromal bed. After intensive treatment with topical corticosteroids, the DLK resolved and corneal transparency was achieved., Conclusions: This case indicates that DLK can occur several years after SMILE. Ocular trauma may be a risk factor for the development of DLK. The prognosis is usually favorable with early diagnosis and treatment with topical corticosteroids.

Purpose: To create a formula to predict refractive correction of autologous lenticule implantation for correction of hyperopia (with myopia in one eye and hyperopia in the contralateral eye)., Methods: In this prospective study, 10 consecutive patients (20 eyes) who had myopia in one eye and hyperopia in the contralateral eye were included. The preoperative spherical equivalent was -3.31 ± 1.73 diopters (D) for the myopic eyes and +4.46 ± 1.97 D for the hyperopic eyes. For each patient, the myopic eye was treated with small incision lenticule extraction and the lenticule was subsequently implanted into the contralateral hyperopic eye. The average length of follow-up was 17 months., Results: All of the operations were successful without complications. At the last visit, the efficacy index (postoperative uncorrected distance visual acuity/preoperative corrected distance visual acuity [CDVA]) of the hyperopic eyes was 0.94 ± 0.35 and the safety index (postoperative CDVA/preoperative CDVA) was 1.36 ± 0.38. No eyes lost any lines of visual acuity. Six of 10 (60%) of the implanted eyes were within ±1.00 D of the intended refractive target. A predictive formula was derived: Lenticule implantation achieved correction (D) (LAC) = 1.224 Lenticule refractive power (D) (LRP) - 0.063 (R 2 =0.92, P < .001). On corneal topography, there was a significant increase in the corneal anterior surface keratometry value postoperatively, whereas the posterior surface keratometry value remained stable (P > .05)., Conclusions: Autologous lenticule implantation could provide a reliable method of correcting hyperopia. The refractive correction formula may require further verification and adjustment. [J Refract Surg. 2017;33(12):827-833.]., (Copyright 2017, SLACK Incorporated.)

Purpose: This study aimed to compare the biomechanical and histopathologic effects of transepithelial and accelerated epithelium-off pulsed-light accelerated corneal collagen cross-linking (CXL)., Methods: A total of 24 New Zealand rabbits were analyzed after sham operation (control) or transepithelial or epithelium-off operation (45 mW/cm for both). The transepithelial group was treated with pulsed-light ultraviolet A for 5 minutes 20 seconds, and the epithelium-off group was treated for 90 seconds. Biomechanical testing, including ultimate stress, Young modulus, and the physiological modulus, was analyzed. Histological changes were evaluated by light microscopy and transmission electron microscopy., Results: The stress-strain curve was nonlinear in both accelerated transepithelial and epithelium-off CXL groups. The stress and elastic moduli were all significantly higher in both experimental groups compared with the control group (P < 0.05), whereas there were no significant differences between the 2 treatment groups (P > 0.05). Six months after the operation, hematoxylin and eosin staining and transmission electron microscopy showed that the subcutaneous collagen fibers were arranged in a regular pattern, and the fiber density was higher in the experimental groups., Conclusions: Both transepithelial and accelerated epithelium-off CXL produced biomechanical and histopathologic improvements, which were not significantly different between the 2 pulsed-light accelerated CXL treatments.

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).

Background: To report a case of interface fluid syndrome (IFS) following small incision lenticule extraction (SMILE) evaluated with corneal densitometry and optical coherence tomography (OCT)., Case Presentation: An 18-year-old man reported sudden vision loss 24 days after SMILE procedure. Intraocular pressure (IOP) was 36.3 mmHg (OD) and 36.7 mmHg (OS) by noncontact tonometry. Moderate corneal edema, interface fluid pocket and haze were observed by OCT and confirmed by corneal densitometry values. Discontinuation of steroids and addition of hypotensive medication were offered immediately. The symptoms were cured after the medication. Changes of corneal densitometry were consistent with the clinical course of IFS., Conclusion: This case illustrates that it is crucial to be aware that a history of SMILE can also cause IFS. Both OCT and corneal densitometry can serve as auxiliary means to evaluate the clinical course of IFS, and appropriate IOP management is an effective approach.

Objective: To investigate the incidence rate, classification, and management of difficulties in lenticule extraction during small incision lenticule extraction (SMILE) with the continuous curvilinear lenticulerrhexis (CCL) technique, and surgical safety and efficacy., Methods: Retrospective study. A total of 342 continuous subjects (680 eyes) received surgical treatment by the same surgeon using the SMILE-CCL technique. The separation was performed only between the cap and anterior surface of the lenticule (8 to 2 o'clock) and at the edge between the cap and posterior surface of the lenticule (1 o'clock). The lenticule was then extracted in a clockwise motion using the CCL technique. Cases with lenticule extraction difficulties were observed through surgery videos. Classification and management of the difficulties were recorded. The rate of intact lenticule extraction was calculated., Results: Twenty-two subjects (22 eyes) had lenticule extraction difficulties. The rate was 3.24%. No difficulty was found in side cut lifting. The microforceps grip loss occurred more than once in five eyes. It was difficult to separate the cap and anterior surface in 12 eyes. One eye had a microdefect in the margin of the lenticule. Five eyes were observed to have single side tearing of side cut. No eyes had double sides tearing of side cut. The microforceps were changed when grip loss occurred more than once. When there were separation difficulties, the pace of lenticule extraction was slowed down, with tearing through the tangential direction of the circle (clockwise). The conventional technique was used in three cases with severe difficulties. All lenticules were successfully extracted from the 22 eyes (100%). Uncorrected visual acuity was ≥1.0 in all eyes at 1 day after surgery. The safety index (the ratio between best corrected visual acuity at 1 month and preoperatively) was 1.11. The efficacy index (the ratio between uncorrected visual acuity at 1 month and preoperative best corrected visual acuity) was 1.04., Conclusions: Difficulties in lenticule extraction occur during SMILE-CCL with a low incidence. Various difficulties can be managed with different techniques. There are no extra effects on surgical safety and efficacy. It is safe and effective to switch back to the conventional technique when severe lenticule extraction difficulties occur.

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: To evaluate the safety, effectiveness, stability, and predictability of implanting autologous lenticules obtained from small incision lenticule extraction for the treatment of hyperopia., Methods: Five patients (10 eyes) with one myopic eye and one hyperopic eye were enrolled. The myopic eye was treated with small incision lenticule extraction; a lenticule was extracted and subsequently implanted in the hyperopic eye. Follow-up was at 1 day, 1, 3, 6, and 9 months, and 1 year postoperatively. Patients received a complete ophthalmologic examination at each visit, including uncorrected distance visual acuity, corrected distance visual acuity, anterior segment optical coherence tomography, and corneal topography., Results: There were no complications in any eye during follow-up. Compared with preoperative levels, at the last follow-up visit the eyes with lenticule implantation showed mean spherical equivalent reduced by 5.53 diopters (residual spherical equivalent was +1.13 to -2.63 diopters), mean uncorrected distance visual acuity increased approximately two lines (approximately 20/63 to 20/40 Snellen), and corrected distance visual acuity in 4 (80%) eyes gained one line, 2 (40%) eyes gained two lines, and 1 (20%) eye gained more than two lines. There was no significant difference (P > .05) in spherical equivalent compared with 1 day postoperatively and the last follow-up visit. Corneal topography showed that the lenticule was uniform and located well; anterior segment optical coherence tomography images showed that the lenticule was transparent and the demarcation line was visible., Conclusions: Implanting an autologous lenticule obtained by small incision lenticule extraction for hyperopia might be safe, effective, and stable, but its predictability should be improved in the future., (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 evaluate the influence of the origin of astigmatism on the correction of myopia or myopic astigmatism by femtosecond laser small-incision lenticule extraction (SMILE)., Setting: Ophthalmology Department, Eye and ENT Hospital, Shanghai, China., Design: Prospective case series., Methods: Small-incision lenticule extraction was performed to correct myopia or myopic astigmatism. Ocular residual astigmatism (ORA) was determined by vector analysis using manifest refraction and Scheimpflug camera imaging of the anterior cornea. Patients were divided into 2 groups according to ORA (high >1.0 diopter [D]; low ≤1.0 D), and procedural efficacy was compared. Patients were examined preoperatively and 1, 3, and 6 months postoperatively., Results: This study comprised 122 right eyes of 122 patients. No significant difference was found in the preoperative manifest astigmatism (target-induced astigmatism [TIA]) between the low ORA group (n = 67) and high ORA group (n = 55). The mean postoperative manifest astigmatism was higher in the high ORA group at all postoperative timepoints (1 month: t = 2.182, P=.031; 3 months: t = 2.30, P=.023; 6 months: t = 2.193, P=.03). The mean index of success (postoperative astigmatism/TIA) was 0.68 in the high ORA group and 0.34 in the low ORA group 1 month postoperatively (t = 2.531, P=.013); 0.73 and 0.39, respectively, at 3 months (t = 2.689, P=.008); and 0.77 and 0.46, respectively, at 6 months (t = 2.105, P=.037)., Conclusion: Small-incision lenticule extraction was effective in correcting astigmatism but may be less effective in correcting ORA., (Copyright © 2015. Published by Elsevier Inc.)

Purpose: To quantitatively analyze the characteristics of Bowman's layer microdistortions after femtosecond laser small incision lenticule extraction (SMILE) among different myopic corrections, and their correlations with stromal lenticule thickness., Methods: In this nonrandomized, prospective, controlled study, 63 eyes of 32 consecutive patients undergoing SMILE were divided into three groups according to the preoperative spherical equivalent (SE): greater than -6.00 D (20 eyes), -3.00 to -6.00 D (26 eyes), and -3.00 D or less (17 eyes). Measurement by slit-lamp microscope, uncorrected distance visual acuity (UDVA), manifest refraction, and Fourier-domain optical coherence tomography (FD-OCT) were conducted preoperatively and 1 day and 1 month postoperatively. Index M was calculated according to the OCT images to indicate the quantity of microdistortions in Bowman's layer., Results: Microdistortions in Bowman's layer were observed in 65.0% (13 of 20 eyes) and 30.8% (8 of 26 eyes) in the greater than -6.00 D and -3.00 to -6.00 D groups, respectively, 1 day postoperatively, and in 60% (12 of 20 eyes) and 23.1% (6 of 26 eyes) 1 month later. No Bowman's layer microdistortion was detected in the -3.00 D or less group postoperatively. The quantitative index M of microdistortions was higher in the greater than -6.00 D group than in the -3.00 to -6.00 D group at 1 day and 1 month (P < .05). There was no statistically significant difference between the indexes M on 1 day compared to 1 month. Index M was correlated with the preoperative SE and lenticule thickness (P < .05)., Conclusion: The incidence and range of microdistortions in Bowman's layer detected after SMILE are positively correlated with the myopic correction. High myopia tends to develop more microdistortions in Bowman's layer after SMILE., (Copyright 2015, SLACK Incorporated.)

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 compare the impact on corneal sensation after small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK (femto-LASIK) in patients with myopia., Methods: In this prospective, nonrandomized comparative study, 71 subjects were enrolled. Thirty-eight eyes of 38 patients underwent SMILE and 33 eyes of 33 patients underwent femto-LASIK. Corneal sensation was tested with Cochet-Bonnet esthesiometry in five corneal areas preoperatively and at 1 week and 1, 3, and 6 months postoperatively. Comparison of corneal sensation was performed for the SMILE and femto-LASIK groups. Additionally, the correlations were evaluated between the postoperative corneal sensation, preoperative spherical equivalent, and ablation depth., Results: All tested areas within the cap or flap demonstrated corneal hypoesthesia immediately after both surgeries. SMILE-treated eyes showed less compromised corneal sensation than femto-LASIK-treated eyes at all postoperative visits in the central, inferior, nasal, and temporal areas at the 1-week and 1-month visits. In the SMILE group, the inferior, nasal, and temporal quadrants recovered faster than other areas. In the femto-LASIK group, the sensation over the flap did not recover to preoperative levels by postoperative 6 months. There was no correlation between postoperative corneal sensation, preoperative spherical equivalent, and ablation depth in both groups., Conclusions: The impairment of corneal sensation was less significant in the SMILE group than in the femto-LASIK group and was independent of preoperative spherical equivalent or ablation depth., (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.