scholarly journals Research Progress on Morphological Changes and Surgery-related Parameters of Corneal Cap in Small Incision Lenticule Extraction

2021 ◽  
Author(s):  
Chen Liang ◽  
Yan Zhang ◽  
Yuxi He ◽  
Shurong Wang
Keyword(s):  
Morphological Changes ◽  
Visual Quality ◽  
Research Progress ◽  
Small Incision Lenticule Extraction ◽  
Small Incision ◽  
Operational Design ◽  
Significant Difference ◽  
Refractive Correction ◽  
Lenticule Extraction ◽  
Different Thickness

Small incision lenticule extraction (SMILE) is an "all-in-one" surgical method for refractive correction. An advantage of the SMILE over traditional surgery is that it depends on the corneal cap’s design. This review discusses the morphological evaluation of the corneal cap, selection of the corneal cap with different thickness and diameters, influence of the corneal cap design on retreatment, and management of corneal cap-related complications. The following points should be recognized to define the correct morphology and design of the operation-related parameters of the corneal cap during SMILE: (1) the thickness and diameter of the corneal cap are predictable and influence postoperative visual quality, (2) the change in anterior surface curvature of the corneal cap should be considered in the design of nomogram value, (3) for patients with moderate myopic correction, early visual quality is better with a 6.9-mm than with a 7.5-mm diameter corneal cap, (4) there is no significant difference in visual quality or biomechanics among corneal caps with different thickness; (5) primary corneal cap thickness plays an important role in the SMILE retreatment, (6) a 7.78-mm diameter corneal cap has a greater risk of suction loss than a 7.60-mm diameter corneal cap, (6) if suction loss occurs when lenticular scanning exceeds 10%, then SMILE can be continued by changing corneal cap thickness, (7) preventive collagen cross-linking with SMILE caps are 90–120 μm thick and 7–7.8 mm in diameter, and (8) properly treating SMILE-related complications ensures better postoperative results. The data presented herein shall deepen the understanding of the importance of the corneal cap during SMILE and provide diversified analysis for personalized operational design of corneal cap parameters.

scholarly journals Detection of Static and Dynamic Stereopsis after Femtosecond Laser Small Incision Lenticule Extraction for High Myopia

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Aiqun Xiang ◽  
Chu Hang ◽  
Xiaoying Wu ◽  
Yewei Yin ◽  
Yanyan Fu ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
High Myopia ◽  
High Energy ◽  
Low Energy ◽  
Small Incision Lenticule Extraction ◽  
Small Incision ◽  
Significant Difference ◽  
Manifest Refraction ◽  
Refractive Correction ◽  
Lenticule Extraction

Purpose. The purpose of this study is to test binocular visual function after femtosecond laser small incision lenticule extraction (SMILE) for high myopia. The traditional Titmus stereotest and dynamic stereotest based on the visual perception biological model were used for comparative analysis. Methods. A total of 43 patients were enrolled in this prospective study. At Week 1, Month 1, and Month 3 after surgery, the Titmus stereotest and dynamic stereotest generated by MATLAB were conducted. Dynamic stereopsis consists of randomly flickering Gabor spots and is divided into two models of high energy and low energy according to flicker frequency. Results. The preoperative manifest refraction spherical equivalent was −7.21 ± 0.70 D. The preoperative anisometropia was 0.52 ± 0.54D. The quartiles of static stereoacuity in preoperation and 3 follow-ups were as follows: 50.00 (25.00, 100.00) in preoperation, 63.00 (40.00, 63.00) at Week 1, 40.00 (32.00, 63.00) at Month 1, and 40.00 (25.00, 50.00) at Month 3. Static stereopsis improved at Month 1 and Month 3 compared with preoperation and Week 1 ( P < 0.05 ). There were statistically significant differences in high energy dynamic stereopsis at Week 1 and Month 1 compared to preoperation ( P < 0.05 ). In addition, significant differences in low energy dynamic stereopsis were detected between Month 1 and preoperation and also at Month 3 compared to Month 1 ( P < 0.05 ). Conclusion. Most high myopia patients have a dynamic stereopsis deficiency before refractive correction. SMILE surgery can improve both static and dynamic stereopsis early in the postoperation period. However, in the long term, there is no significant difference or even a decrease in dynamic stereopsis.

scholarly journals SMILE and Wavefront-Guided LASIK Out-Compete Other Refractive Surgeries in Ameliorating the Induction of High-Order Aberrations in Anterior Corneal Surface

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Min-jie Ye ◽  
Cai-yuan Liu ◽  
Rong-feng Liao ◽  
Zheng-yu Gu ◽  
Bing-ying Zhao ◽  
...  
Keyword(s):  
Spherical Aberration ◽  
Laser In Situ Keratomileusis ◽  
Small Incision Lenticule Extraction ◽  
Corneal Surface ◽  
Small Incision ◽  
Significant Difference ◽  
Lenticule Extraction ◽  
A Prospective Study ◽  
High Order Aberrations

Purpose. To compare the change of anterior corneal higher-order aberrations (HOAs) after laser in situ keratomileusis (LASIK), wavefront-guided LASIK with iris registration (WF-LASIK), femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK), and small incision lenticule extraction (SMILE).Methods. In a prospective study, 82 eyes underwent LASIK, 119 eyes underwent WF-LASIK, 88 eyes underwent FS-LASIK, and 170 eyes underwent SMILE surgery. HOAs were measured with Pentacam device preoperatively and 6 months after surgery. The aberrations were described as Zernike polynomials, and analysis focused on total HOAs, spherical aberration (SA), horizontal coma, and vertical coma over 6 mm diameter central corneal zone.Results. Six months postoperatively, all procedures result in increase of anterior corneal total HOAs and SA. There were no significant differences in the induced HOAs between LASIK and FS-LASIK, while SMILE induced fewer total HOAs and SA compared with LASIK and FS-LASIK. Similarly, WF-LASIK also induced less total HOAs than LASIK and FS-LASIK, but only fewer SA than FS-LASIK (P<0.05). No significant difference could be detected in the induced total HOAs and SA between SMILE and WF-LASIK, whereas SMILE induced more horizontal coma and vertical coma compared with WF-LASIK (P<0.05).Conclusion. FS-LASIK and LASIK induced comparable anterior corneal HOAs. Compared to LASIK and FS-LASIK, both SMILE and WF-LASIK showed advantages in inducing less total HOAs. In addition, SMILE also possesses better ability to reduce the induction of SA in comparison with LASIK and FS-LASIK. However, SMILE induced more horizontal coma and vertical coma compared with WF-LASIK, indicating that the centration of SMILE procedure is probably less precise than WF-LASIK.

scholarly journals Clinical outcomes after small incision lenticule extraction versus femtosecond laser-assisted LASIK for high myopia: a Meta-analysis.

2020 ◽  
Author(s):  
Yanyan Fu ◽  
Yewei Yin ◽  
Yang Zhao ◽  
Aiqun Xiang ◽  
Ying Lu ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Clinical Outcomes ◽  
High Myopia ◽  
Spherical Aberration ◽  
Meta Analysis ◽  
Small Incision Lenticule Extraction ◽  
Small Incision ◽  
Significant Difference ◽  
Lenticule Extraction

Abstract Background To compare postoperative clinical outcomes of high myopia after being treated by Small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK).Methods Comprehensive studies were conducted on the PubMed, MEDLINE, EMBASE, the Cochrane Library, and Chinese databases.Trials meeting the selection criteria were quality appraised, and the data were extracted by 2 independent authors, and the RevMan 5.3 version software were used in analyzing.Result Ten studies involving 637 patients (1093 eyes;575 eyes in the SMILE group and 518 eyes in the FS-LASIK group) were included in this meta-analysis. Pooled result revealed no significant differences in the following outcomes: the logMAR values of postoperative UDVA(WMD = -0.01, 95% CI: -0.02,0.00, I²=0%, P = 0.10 at postoperative 1mo; WMD =-0.01, 95% CI: -0.00 to 0.01, I²=0%,P = 0.35 at postoperative 3mo; WMD = -0.01, 95% CI:-0.02 to 0.01, I²=17%,P = 0.26 at long term), the logMAR values of postoperative CDVA(WMD = -0.02, 95% CI, -0.04 to 0.00, I²=0%, P = 0.11),and the postoperative mean refractive SE (WMD =0.02, 95% CI:0.04 to 0.08, I²=29%, P=0.60) . In the long-term observation, postoperative tHOA (WMD =-0.10, 95% CI:-0.13 to -0.07, I²=15%, P<0.00001)and postoperative spherical aberration (WMD =-0.13, 95% CI:--0.17 to -0.09, I²=38%, P<0.00001) were found to be less in the SMILE group compared with the FS-LASIK group, but no significant difference was found in postoperative coma (WMD =-0.02, 95% CI:-0.04 to 0.00, I²=98%, P=0.40).We also found greater PCE change post FS-LASIK than SMILE at long term follow-ups(WMD =-0.69, 95% CI:-1.36 to -0.01, I²=0%, P<0.05, however, there was no significant difference between the two groups at 3- or 6- months.(WMD =-0.19, 95% CI:-0.41 to 0.03, I²=31%, P=0.09;WMD =-0.20, 95% CI:-0.50 to 0.10, I²=17%, P=0.20)Conclusion For patients with high myopia, both SMILE and FS-LASIK are safe and efficacious. However, SMILE induced less tHOA and spherical aberration compared with FS-LASIK. Besides, FS-LASIK showed a greater increase in PCE than SMILE only at long term follow-ups. It remains to be seen whether the patients can get a better visual quality after SMILE and more comparative studies focused on high myopia is necessary.

scholarly journals Long-term Visual Quality after Small Incision Lenticule Extraction (SMILE) and Laser Epithelial Keratomileusis (LASEK) for Low Myopia

2021 ◽  
Author(s):  
Mengjun Fu ◽  
Meiyan Li ◽  
Ruoyan Wei ◽  
Chuanwei Zhang ◽  
Yangyi Huang ◽  
...  
Keyword(s):  
Spherical Aberration ◽  
Visual Quality ◽  
Small Incision Lenticule Extraction ◽  
Wavefront Aberrations ◽  
Small Incision ◽  
Patient Reported ◽  
Manifest Refraction ◽  
Lenticule Extraction ◽  
Efficacy Index

Abstract Background: Few studies have reported the visual outcomes of small-incision lenticule extraction (SMILE) and laser-assisted epithelial keratomileusis (LASEK) for myopia correction. This study aims to compare the visual quality and corneal wavefront aberrations after SMILE and LASEK for low-myopia correction.Methods: In this prospective study, we included 29 eyes of 29 patients who received SMILE, and 23 eyes of 23 patients who received LASEK between June 2018 and January 2019. The following measurements were assessed: uncorrected (UDVA) and corrected (CDVA) distance visual acuity, manifest refraction, corneal wavefront aberrations, and subjective visual quality. All patients were followed up for two years.Results: All procedures were uneventful. An efficacy index of 1.19 ± 0.17 was established in the SMILE group and 1.23 ± 0.20 in the LASEK group. No eyes lost more than two lines of CDVA. We found that 93% (27/29) of the treated eyes in the SMILE group and 91% (21/23) in the LASEK group had spherical equivalent (SE) within ± 0.25D. The increases in the total corneal spherical aberration and the corneal front spherical aberration were lower in the SMILE group than in the LASEK group (P < 0.01). In contrast, the increases in the total corneal vertical coma and the corneal front vertical coma in the SMILE group were greater than those in the LASEK group (P < 0.01).Conclusion: Both SMILE and LASEK have good safety, stability, and patient-reported satisfaction for low myopia. SMILE induced less corneal spherical aberration but greater vertical coma than LASEK.

Influence of age on small incision lenticule extraction outcomes

2020 ◽  
pp. bjophthalmol-2020-316865
Author(s):  
Laura Primavera ◽  
Mario Canto-Cerdan ◽  
Jorge L Alio ◽  
Jorge L Alio del Barrio
Keyword(s):  
Corneal Stroma ◽  
Study Groups ◽  
Visual Response ◽  
Small Incision Lenticule Extraction ◽  
Small Incision ◽  
Refractive Outcomes ◽  
Significant Difference ◽  
Lenticule Extraction ◽  
The Mean ◽  
Over 40 Years

PurposeTo evaluate the influence of patient’s age at the time of surgery on small incision lenticule extraction (SMILE) refractive outcomes.MethodsThis is a retrospective, consecutive, comparative study. We compared the refractive outcomes after myopic SMILE from two groups of patients divided by age (patients ≤35 and ≥40 years old). All eyes were evaluated preoperatively and at 1 and 6 months postoperatively. Main outcome measures were differences on efficacy, safety, predictability and astigmatic changes by vector analysis with ASSORT software between both study groups.Results102 matched eyes of 53 patients were included. Preoperatively, we evidenced no differences in the mean SE or astigmatism between groups. However, 6 months postoperatively we observed a significantly worse mean astigmatism (p=0.019), while not regarding SE, in the older population, with a trend towards undercorrection of the refractive cylinder in the ≥40 group. We also observed a statistically significant difference in the efficacy (0.86–1 month and 0.97–6 months in ≥40group vs 0.97–1 month and 1.07–6 months in the ≤35 group; p=0.003) and safety indexes (0.93–1 month and 1.04–6 months in ≥40 group vs 1.0–1 month and 1.11–6 months in the ≤35 group; p=0.008) at 6 months among groups.ConclusionsPost-SMILE refractive outcomes in those patients over 40 years of age, although acceptable, are not as good as those obtained in younger patients, showing a significantly lower efficacy and safety indexes, and poorer astigmatic outcomes, with a tendency towards undercorrection. We hypothetise that the increased corneal stroma stiffness in the aged group modifies the post-SMILE corneal stroma remodelling capacity, thus affecting the SMILE refractive and visual response.

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