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Purpose: To investigate achieved lenticule diameter (ALD) and functional optical zone (FOZ) following femtosecond laser-assisted lenticule intrastromal keratoplasty (FS-LIKE) or small incision lenticule intrastromal keratoplasty (SMI-LIKE)., Methods: Small incision lenticule extraction (SMILE)-derived human lenticules were placed on the surface of a contact glass (CG) and model eye (ME). Ex vivo ALDs were assessed at different hydration times. The ALD and FOZ were obtained using optical coherence tomography and Scheimpflug tomography at 6 months after lenticule implantation., Results: At 1 hour after hydration, lenticules achieved a slightly larger CG-loading ALD (6.63 ± 0.07 mm) and similar ME-loading ALD (6.53 ± 0.07 mm) as compared to a programmed optical zone (POZ) of 6.5 mm ( P < .001). At 6 months after surgery, FS-LIKE with a POZ of 6.5 mm obtained an ALD of 6.20 ± 0.21 mm, which was larger than SMI-LIKE with a POZ of 6.64 mm (5.90 ± 0.14 mm, P = .001). The mean FOZ diameters were 5.33 ± 0.28 and 5.11 ± 0.14 mm for the FS-LIKE and SMI-LIKE groups, respectively ( P = .022). The absence of significant differences in the ALD and FOZ among the different meridians indicated that the achieved lenticule and optical zone shapes were circular., Conclusions: An accurate lenticular size could be obtained from SMILE, and FS-LIKE could achieve a larger FOZ than SMI-LIKE, attributed to attaining a larger ALD. [ J Refract Surg . 2022;38(12):791-796.] .

Purpose: To investigate optical zone decentration following femtosecond laser-assisted lenticule intrastromal keratoplasty (FS-LIKE) or small incision lenticule intrastromal keratoplasty (SMI-LIKE) for correcting hyperopia., Methods: This study analyzed decentration values obtained from optical coherence tomography (OCT) and tangential topography difference maps of 23 eyes (18 patients) undergoing FS-LIKE (n = 12) or SMI-LIKE (n = 11) via the concentric centration method. Total higher order aberrations (HOAs) and component aberrations were measured preoperatively and 6 months postoperatively., Results: The mean optical zone decentration was 0.27 ± 0.08 and 0.39 ± 0.16 mm for the FS-LIKE and SMI-LIKE groups, respectively ( P = .039). A significant difference was noted in lenticule decentration between the two groups (0.18 vs 0.37 mm), whereas no significant difference was observed in stromal bed (pocket) decentration between the two groups (0.10 vs 0.12 mm). Six months after surgery, the spherical equivalent showed a reduction of 6.14 ± 2.44 and 6.10 ± 1.79 diopters (D) for the two groups, respectively ( P = .971), whereas the surgically induced astigmatism was 0.68 ± 0.49 and 1.56 ± 0.78 D for the two groups, respectively ( P = .004). Furthermore, induction of HOAs in the SMI-LIKE group was significantly larger than that in the FS-LIKE group ( P = .013)., Conclusions: FS-LIKE can yield improved treatment centration and less induction of total HOAs. [ J Refract Surg . 2022;38(3):184-190.] .

Purpose: To investigate 2-year visual outcomes, stability, and predictability after allogenic lenticule implantation in a 100-µm pocket for moderate to high hyperopia correction., Methods: In this prospective case series, 14 eyes of 9 patients with moderate to high hyperopia ranging from +3.00 to +8.00 diopters sphere were included between March and September 2018. Allogenic lenticules extracted from myopic small incision lenticule extraction were implanted into a pocket created by femtosecond laser at a 100-µm depth in recipients with hyperopia. All patients were followed up for 2 years. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity, manifest refraction, corneal topography, Fourier-domain optical coherence tomography, and in vivo confocal microscopy were examined., Results: At postoperative 2 years, 2 eyes (14.3%) gained one line of CDVA, 11 eyes (78.6%) had unchanged CDVA, and 1 eye (7.1%) lost one line of CDVA. No eyes lost two or more lines of CDVA. Twelve of the treated eyes (85.7%) had postoperative uncorrected near visual acuity equal to or better than pre-operative values. The spherical equivalent decreased from +5.53 ± 1.45 D preoperatively to -0.60 ± 1.20 D at postoperative year 2 ( P < .001). The anterior mean keratometric readings increased from 42.41 ± 1.03 D preoperatively to 48.38 ± 1.98 D at postoperative year 2 ( P < .001). Of 14 treated eyes, 10 eyes (71.4%) had spherical equivalent within ±1.00 D., Conclusions: The findings suggest that allogenic lenticule transplantation may be a promising option for the correction of moderate to high hyperopia. [ J Refract Surg . 2021;37(11):734-740.] .

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.)

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 describe a case in which post-LASIK corneal ectasia was treated using an allogeneic lenticule implanted into the recipient eye., Methods: A 29-year-old man presented with bilateral ectasia 10 years after LASIK. Manifest refraction was -1.50 -3.25 × 15° in the right eye and -13.50 -6.00 × 10° in the left eye. Because of contact lens intolerance in the left eye, the authors decided to implant an allogenic corneal lenticule, created by small incision lenticule extraction with the VisuMax laser (Carl Zeiss Meditec, Jena, Germany) in a donor eye with a refraction of +5.75 -0.50 × 15°. The intended peripheral thickness was 116 μm and the central thickness was 20 μm. The lenticule was placed under the original LASIK flap in the left eye., Results: Ten months after surgery, refraction of the left eye had improved to -3.25 -1.50 × 10° with a corrected distance visual acuity of 20/40. The front corneal flat and steep values were decreased by 6.20 and 5.90 diopters (D), respectively, relative to corresponding preoperative values. The cornea remained clear throughout the follow-up., Conclusions: Implantation of an allogenic lenticule may be an option in the treatment of advanced ectasia. [J Refract Surg. 2018;34(5):347-350.]., (Copyright 2018, SLACK Incorporated.)

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: 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: 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 develop and evaluate the new continuous curvilinear lenticulerrhexis (CCL) technique for small incision lenticule extraction., Methods: Thirty-one eyes of 20 patients with myopia were included in the study. The CCL technique for lenticule extraction was developed and used in 16 eyes of 10 patients (CCL group). The traditional technique of lenticule extraction was used in 15 eyes of 10 patients (traditional group). Uncorrected and corrected distance visual acuity, manifest refraction, lenticule quality, the duration of the extraction procedure, microdistorsions in Bowman's layer under optical coherence tomography (Optovue OCT; Optovue, Inc., Fremont, CA), and adverse events were evaluated at 1 day and 1 month postoperatively., Results: At the first postoperative month, all eyes in both groups had an uncorrected distance visual acuity of 1.0 or better. The safety indices were 1.12 and 1.09 for the CCL and traditional groups, respectively. The efficacy indices were 1.06 and 1.09 for the CCL and traditional groups, respectively. All lenticules in the CCL group had intact, round margins, whereas one lenticule in the traditional group had a microdefect margin. There was no statistically significant difference in duration of lenticule extraction or microdistorsions in Bowman's layer. No eyes in the CCL group developed diffuse lamellar keratitis, as compared to one eye in the traditional group., Conclusions: The CCL technique exhibited excellent safety and efficacy for myopia correction, suggesting CCL is a promising technique that merits further development and study., (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 study microdistortions in Bowman's layer after femtosecond laser small incision lenticule extraction (SMILE) using Fourier-domain optical coherence tomography (OCT) and to investigate possible sources and potential visual impacts., Methods: A nonrandomized controlled prospective study enrolled 52 eyes of 29 consecutive patients undergoing SMILE, with spherical equivalent of -6.33 ± 1.88 diopters and 4.2 mm superior incision. The microdistortions in Bowman’s layer were counted at 1 day, 1 week, and 1 month postoperatively and at long-term follow-up. Another 38 eyes of 20 patients undergoing femtosecond laser-assisted LASIK (FS-LASIK) were examined at 1 day and long-term postoperatively as the control group., Results: Microdistortions in Bowman’s layer were observed by OCT, with no clinically significant corneal striae under slit-lamp microscopy, in 46 eyes (88.5%) on day 1 after SMILE and in 16 eyes (42.1%) after FS-LASIK, with more in SMILE eyes than in FS-LASIK eyes. The amount decreased at 1 week and then remained stable. There were more microdistortions in the center area than in the periphery in both groups. Microdistortions were more in the inferior than the superior quadrant on the first day after SMILE but there was no difference at long-term follow-up. Microdistortions after SMILE were associated with the refractive lenticule thickness and surgery order but had no significant impact on long-term visual outcomes or wavefront aberrations., Conclusions: Microdistortions in Bowman's layer after SMILE were associated with the refractive lenticule thickness and surgery order. The microdistortions remained stable after 1 week and had no impact on long-term visual performance.