Longitudinal analysis of wound healing response post SMILE and LASIK surgery using proteomic profiling of tears.

Different types of refractive surgeries often exhibit differences in wound healing responses. The current study investigated post-operative tear protein profiles in subjects who underwent LASIK and SMILE to elucidate global changes to the proteomic profile during the period the patient cornea undergoes healing. In this study, 10 patients underwent LASIK and SMILE surgery with a contralateral paired eye design. Tear samples were collected using Schirmer's strips preoperatively, at 1 month, 3 months and 6 months postoperatively. Quantitative ITRAQ labeled proteomics was performed and the tear protein ratios were normalized to pre-operative protein levels for each subject. Whole proteomics identified 1345 proteins in tears from LASIK and 1584 proteins in SMILE across time points. About 67 proteins were common in LASIK and SMILE tears across all the time points. Wound healing responses were differentially regulated between two refractive surgeries (SMILE and LASIK). The proteins Ceruloplasmin, Clusterin, Serotransferrin were upregulated at 1 month and 3 months and downregulated at 6 months post operatively in LASIK surgery where as in SMILE these were downregulated. Galectin 3 binding protein showed upregulation at 1 month and the levels decreased at 3 months and 6 months postop in LASIK tears whereas the levels increased at 3 months and 6 months post-op in SMILE tears. The levels of proteins that protect from oxidative stress were higher in SMILE as compared to LASIK postoperatively. The extracellular matrix proteins showed an increase in expression at 6 months in SMILE tears and was stabilized at 6 months in LASIK tears post operatively. Different refractive surgeries induce distinct wound healing responses as identified in tears. This study has implications in targeting key proteins for improving the clinical outcome postrefractive surgery.

Femtosecond laser-assisted in situ keratomileusis versus small-incision lenticule extraction: current approach based on evidence.

PURPOSE OF REVIEW: Laser keratorefractive surgery achieves excellent visual outcomes for refractive error correction. With femtosecond laser, small incision lenticule extraction (SMILE) is an increasingly viable alternative to laser-assisted in situ keratomileusis (LASIK). Comparative studies demonstrate similar efficacy and predictability between SMILE and LASIK, making it difficult for clinicians to choose which to use. This review thus compares femtosecond-LASIK (FS-LASK) and SMILE in various scenarios, to assist clinicians in deciding which refractive surgery procedure to recommend. RECENT FINDINGS: SMILE may be superior for highly myopic eyes due to a smaller decrease in functional optical zone. SMILE further induces less spherical aberration and less overall higher order aberrations in mesopic conditions. SMIILE also has less postoperative dry eye, making it suitable those with preexisting dry eye. For low to moderate myopic astigmatism correction, FS-LASIK has less undercorrection compared to SMILE. Lastly, SMILE has not yet received Food and Drug Administration or Conformité Européenne approval for hyperopic correction, rendering FS-LASIK the choice of procedure for hyperopic correction. SUMMARY: Both FS-LASIK and SMILE demonstrate good efficacy and predictability. Understanding specific clinical scenarios where one may be superior to the other will aid clinicians in choosing the most suitable procedure for personalized care.

Interface fluid syndrome caused by the corneal perforation injury after small incision lenticule extraction: a case report.

BACKGROUND: To report a case of interface fluid syndrome (IFS) following traumatic corneal perforation repair after small incision lenticule extraction (SMILE). CASE PRESENTATION: A 23-year-old woman, with a past history of SMILE, was struck in the left eye with a barbecue prod and subsequently underwent corneal perforation repair at local hospital. Primary wound repaired with a single 10 - 0 nylon suture at the area of leakage. After the surgery, her best corrected visual acuity (BCVA) was 20/30. Four days later, she presented at our hospital with blurred vision, and interface fluid syndrome (IFS) was diagnosed. Intraoperative optical coherence tomography (iOCT) was used to guide the resuturing of the corneal perforation in the left eye, followed by anterior chamber gas injection. At the first postoperative month, the BCVA was 20/25. The corneal cap adhered closely to the stroma, the surface became smooth. CONCLUSIONS: This case illustrates that any corneal perforation following lamellar surgery, including SMILE, may lead to IFS. It is crucial to consider the depth of corneal perforation, and intraoperative optical coherence tomography (iOCT) plays a unique role in the repair procedure.

Repeatability and reproducibility of a new method for centration analysis via optical zone tangent points after corneal refractive surgery.

PURPOSE: To investigate the repeatability and reproducibility of a new method for centration analysis after small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK (FS-LASIK). METHODS: This study comprised 29 eyes treated with SMILE and 24 with FS-LASIK. Decentrations were analyzed using tangential and pachymetry difference maps respectively. Both difference maps were generated with a Scheimpflug tomographer (Pentacam) for each eye, using preoperative and 3-month postoperative scans. Repeatability and reproducibility were evaluated by calculating the intraclass correlation coefficient (ICC), within-subject standard deviation (Sw), and coefficient of repeatability (CR). RESULTS: ICC, Sw, and CR showed good to excellent repeatability in locating the coordinates of the optical zone (OZ) center on both maps, with values ranging from 0.84 to 0.96, 0.03 to 0.13, and 0.08 to 0.36 respectively. The repeatability of the total decentration from the preoperative corneal vertex on the tangential curvature difference maps( d TC ) and the pachymetry difference maps( d PC ) were moderate and good, respectively. The ICC, Sw, and CR of d TC were 0.63, 0.09, and 0.25, respectively. The ICC, Sw, and CR of d PC were 0.77, 0.10, and 0.28, respectively. The reproducibility of the OZ center measurements was excellent for the tangential difference maps (ICC ≥ 0.97 ) and good for the pachymetry difference maps (ICC ≥ 0.86). ICC, Sw, and CR showed excellent reproducibility of d TC , with values of 0.95, 0.03, and 0.08, respectively. ICC, Sw, and CR showed good reproducibility of d PC , with values of 0.89, 0.06, and 0.17, respectively. CONCLUSION: The centration analysis method used in this study showed good to excellent repeatability and reproducibility in locating the coordinates of the center of the OZ on the tangential and pachymetry difference maps.

Association of myopia and astigmatism with postoperative ocular high order aberration after small incision lenticule extraction.

OBJECTIVE: To investigate the correlation between higher-order aberrations (HOA) after small incision lenticule extraction (SMILE) and the severity of myopia and astigmatism, along with the relevant factors. These findings will provide valuable insights for decreasing the occurrence of HOA after SMILE and enhancing visual quality. METHODS: A total of 75 patients (150 eyes) with myopia and astigmatism who underwent SMILE were categorized into four groups based on the severity of myopia and astigmatism: Myopia Group 1 (Group M1, spherical diopter ranged from -1.00 D to -4.00 D), Myopia Group 2 (Group M2, spherical diopter ranged from -4.10 D to -10.00 D), Astigmatism Group 1 (Group A1, cylindrical diopter ranged from 0 D to -1.00 D), and Astigmatism Group 2 (Group A2, cylindrical diopter ranged from -1.10 D to -3.00 D). A comprehensive assessment was performed to examine the association between HOA and various relevant factors, including a detailed analysis of the subgroups. RESULTS: Group M1 had significantly lower levels of total eye coma aberration (CA), corneal total HOA (tHOA), internal tHOA, and vertical CA ( Z 3 - 1 ) after SMILE than Group M2 (P < 0.05). Similarly, Group A1 had significantly lower levels of total eye tHOA, CA, trefoil aberration (TA), corneal tHOA, TA, and vertical TA ( Z 3 - 3 ) after SMILE than Group A2 (P < 0.05). Pearson correlation analysis indicated a statistically significant positive relationship between the severity of myopia/astigmatism and most HOA (P < 0.05). Subgroup evaluations demonstrated a notable increase in postoperative HOA associated with myopia and astigmatism in Groups M2 and A2 compared with the control group. Lenticule thickness, postoperative central corneal thickness (CCT), postoperative uncorrected distance visual acuity (UDVA), and postoperative corneal Km and Cyl were strongly correlated with most HOA. Age, eyes, and postoperative intraocular pressure (IOP) were only associated with specific HOA. CONCLUSION: HOA positively correlated with the severity of myopia and astigmatism after SMILE. However, this relationship was not linear. HOA after SMILE was influenced by various factors, and additional specialized investigations are required to establish its clinical importance.

Comparison of long-term changes in the effective optical zone following SMILE and FS-LASIK for moderate and high myopia.

BACKGROUND: Visual quality after corneal refractive surgery is linked to the postoperative effective optical zone (EOZ). This study aims to compare long-term changes in the EOZ following small incision lenticule extraction (SMILE) and femtosecond laser-assisted in-situ keratomileusis (FS-LASIK) for moderate and high myopia. METHODS: This study included 42 patients (72 eyes) who underwent either SMILE (36 eyes) or FS-LASIK (36 eyes). A custom software program based on the tangential curvature difference map of the Pentacam HR (Oculus Optikgeräte GmbH) was used to define the EOZ at 3 and 7 years postoperatively. The EOZ, its chronological changes compared to the programmed optical zone (POZ), and the corneal wavefront aberrations following SMILE and FS-LASIK were analyzed. Correlations between the EOZ changes and relevant parameters were evaluated. RESULTS: Three years postoperatively, EOZ following SMILE and FS-LASIK were 5.13 ± 0.27 mm and 4.70 ± 0.24 mm (P < 0.001), respectively. Seven years postoperatively, EOZ following SMILE and FS-LASIK decreased to 5.03 ± 0.28 mm and 4.63 ± 0.23 mm (P < 0.001), respectively. At postoperative 7 years, the percentages of EOZ/POZ were negatively correlated with Q-value changes (ß = -5.120, P = 0.009) following SMILE and positively correlated with the cylinder correction (ß = 1.184, P = 0.004) following FS-LASIK. The induced spherical aberrations in the SMILE group were less than those in the FS-LASIK group (P < 0.05) and were negatively correlated with the EOZ/POZ (ß = -16.653, P < 0.001). CONCLUSIONS: The EOZ following SMILE was larger than that following FS-LASIK in the long postoperative term for moderate and high myopia. Furthermore, a continual reduction in the EOZ was noted after both surgical modalities.

Knowledge, attitudes, and practices toward femtosecond laser small incision lenticule extraction surgery and postoperative care among recipients.

BACKGROUND: To investigate the knowledge, attitudes, and practices (KAP) of individuals who underwent small incision lenticule extraction (SMILE) surgery and explore the influencing factors. METHODS: This cross-sectional study was conducted from June 21, 2023, to August 13, 2023, at Xiangyang Central Hospital. The participants were patients who had undergone SMILE surgery. The self-designed questionnaire had a Cronbach's α = 0.849. Multivariable analyses were performed to determine the factors influencing the KAP scores. RESULTS: Finally, 485 valid questionnaires were analyzed. The median knowledge score was 14 (/17, 82.4%; IQR: 12-15). The median attitude score was 15 (/20, 75.0%; IQR: 14-16). The median practice score was 48 (/60, 80.0%; IQR: 42-54). The knowledge scores correlated to the attitude (r = 0.323, P < 0.001) and practice (r = 0.202, P < 0.001) scores, while the attitude scores correlated to the practice scores (r = 0.065, P < 0.001). College diploma (OR = 0.299, 95%CI: 0.110-0.812, P = 0.018), myopia for < 2 years (OR = 0.177, 95%CI: 0.060-0.526), and not receiving proper eye training (OR = 0.588, 95%CI: 0.402-0.862) were independently associated with knowledge. Being 19-30 years old (OR = 0.421, 95%CI: 0.235-0.756), being ≥ 31 years old (OR = 0.259, 95%CI: 0.111-0.601), myopia for 2-5 years (OR = 0.476, 95%CI: 0.232-0.978), myopia for 5-10 years (OR = 0.480, 95%CI: 0.263-0.875), and moderate myopia in the right eye (OR = 1.745, 95%CI: 1.024-2.974) were independently associated with attitude. Female gender (OR = 1.826, 95%CI: 1.196-2.787), being ≥ 31 years (OR = 2.587, 95%CI: 1.113-6.014), college diploma (OR = 3.436, 95%CI: 1.366-8.641), bachelor's degree (OR = 2.826, 95%CI: 1.214-6.581), and not having proper eye training (OR = 0.458, 95%CI: 0.310-0.677) were independently associated with practice. CONCLUSIONS: Patients who underwent SMILE had high KAP regarding SMILE. This study identified KAP items that would warrant education.

Banking of post-SMILE stromal lenticules for additive keratoplasty: A new challenge for eye banks?

PURPOSE: ReLEx (Refractive Lenticule Extraction) Small Incision Lenticule Extraction (SMILE), the second generation of ReLEx Femtosecond Lenticule Extraction (FLEx), is a minimally invasive, flapless procedure designed to treat refractive errors such as myopia, hyperopia, presbyopia, and astigmatism. This review aims to provide a comprehensive overview of the methods for preserving SMILE-derived lenticules and discusses their potential future applications. METHODS: A narrative literature review was conducted using PubMed, Scopus, and Web of Science databases, focusing on articles published up to January 2024 and available in English. The authors also evaluated the reference lists of the collected papers to identify any additional relevant research. RESULTS: No standardized protocols currently exist for the storage or clinical application of SMILE-derived lenticules. However, these lenticules present a promising resource for therapeutic uses, particularly in addressing the shortage of donor corneal tissues. Their potential applications include inlay and overlay additive keratoplasty, as well as other ocular surface applications. Further research is needed to establish reliable protocols for their preservation and clinical use. CONCLUSION: SMILE-derived lenticules offer significant potential as an alternative to donor corneal tissues. Standardizing their storage and application methods could enhance their use in clinical settings.

Early elastic and viscoelastic corneal biomechanical changes after photorefractive keratectomy and small incision lenticule extraction.

PURPOSE: To compare early changes in the corneal biomechanical parameters after photorefractive keratectomy (PRK) and small incision lenticule extraction (SMILE) and their correlations with corneal shape parameters. METHODS: One hundred twenty four eyes received myopic PRK and SMILE for similar amounts of myopia. Corneal tomography with Pentacam HR, biomechanical parameters using Corvis ST, and Ocular Response Analyzer (ORA) were evaluated before and 2 weeks after surgery. The change in each parameter was compared between groups, while the difference in central corneal thickness and cornea-compensated intraocular pressure measured before and after surgery were considered as covariates. RESULTS: A significant reduction was seen in the corneal stiffness parameter at first applanation, and an increase in deformation amplitude ratio (DAR), and integrated inverse radius (IIR) in both groups after surgery (p < 0.001) Changes in DAR, and IIR were significantly greater in the SMILE than in the PRK group (p < 0.001) Corneal hysteresis (CH) and corneal resistance factor (CRF) decreased in both SMILE and PRK groups after surgery, (p < 0.001) with no statistically significant difference between groups (p > 0.05) Among new Corvis ST parameters, DAR showed a significant correlation with changes in Ambrosio relational thickness in both groups (p < 0.05). CONCLUSIONS: Both techniques caused significant changes in corneal biomechanics in the early postoperative period, with greater elastic changes in the SMILE group compared to the PRK group, likely due to lower tension in the SMILE cap and thinner residual stromal bed in SMILE. There were no differences in viscoelastic changes between them, so the lower CH may reflect the volume of tissue removed.

Total and simulated keratometry measurements using IOLMaster 700 and Pentacam AXL after small incision lenticule extraction.

PURPOSE: Calculating the intraocular lens (IOL) in patients after corneal refractive surgery presents a challenge. Because an overestimation of corneal power in cases undergone this surgery leading to a subsequent under-correction of IOL power. However, recent advancements in technology have eliable measurement of total corneal power. The aim of this research was to assess the agreement in simulated keratometry (SimK) and total keratometry (TK) values between IOLMaster 700 and Pentacam AXL. METHODS: The study involved 99 patients (99 eyes) undergone small incision lenticule extraction (SMILE) surgery. Each patient underwent scans using IOL Master 700 and Pentacam AXL. The following parameters were recorded: SimK1, SimK2, Total K1 (TK1), and Total K2 (TK2) for IOLMaster 700; and SimK1, SimK2, True Net Power (TNP) K1, TNPK2, Total Corneal Refractive Power (TCRP) K1, and TCRP K2 for Pentacam AXL. Agreement between the two devices was evaluated using Bland-Altman plot, while paired t-test was utilized to compare any differences in the same parameter by both instruments. RESULTS: The results revealed a strong correlation between the two devices.Noticeable comparability was identified for all SimK variables. However, there were noticeable differences in TK measurements as well as TK1-TNPK1, TK2-TNP K2, TK1-TCRP K1, and TK2-TCRP K2 parameters when comparing the two devices. The IOLMaster 700 consistently measured steeper values than the Pentacam AXL, with significant and clinically relevant differences of 1.34, 1.37, 0.87, and 0.95 diopters, respectively. CONCLUSION: While there was a noticeable correlation between the IOLMaster 700 and Pentacam AXL in SimK measurements, a marked difference was noted in TK values. The two devices cannot be used interchangeably when quantifying TK values.

[Whether laser corneal refractive surgery combined with presbyopia correction technology could treat presbyopia].

Presbyopia refers to a phenomenon in which the ability of the eye to accommodate is insufficient to meet the daily demand for proximity due to age. In modern society, more and more patients over 40 years old want to solve visual problems caused by presbyopia and refractive errors, which poses new challenges for clinical laser corneal refractive surgery, and a variety of combined presbyopia correction technologies and programs have emerged. However, whether laser corneal refractive surgery combined with presbyopia correction technology could treat presbyopia deserves clinical attention. Based on the mechanism of laser corneal refractive surgery and various presbyopia correction techniques, this article deeply analyzes the purpose and effect of laser corneal refractive surgery combined with presbyopia correction technology. It is proposed that this surgical treatment could only play a role in correcting presbyopia at present and should be performed accordingly.

[Chinese expert consensus on the perioperative medication in laser corneal refractive surgery (2024)].

With the increasing incidence of myopia year by year and the continuous progress of various treatment techniques, laser corneal refractive surgery has become one of the important ways to correct refractive errors. The rational drug use in the perioperative period is important for the success of surgery and reduction of complications. In 2019, based on the development of laser corneal refractive surgery in China, experts from the Refractive Surgery Experts Group of Ocular Microcirculation Branch of Chinese Society of Microcirculation and the Ophthalmology Branch in the Chinese Medical Association formed the "Chinese Expert Consensus on the Perioperative Medication in Laser Corneal Refractive Surgery (2019)". To further promote the expansion of new clinical technologies and surgical methods, and to improve surgical efficacy, the Refractive Surgery Experts Group of Ocular Microcirculation Branch of Chinese Society of Microcirculation, according to the latest domestic and foreign research results, has recently updated the consensus after a collective discussion.

[Chinese expert consensus on the prevention and treatment of complications of laser corneal refractive surgery (2024)].

Laser corneal refractive surgery has been carried out in China for three decades. The safety, efficacy, predictability, and long-term stability of the surgery have been well established. In the past 10 years, with the wide use of small incision lenticule extraction (SMILE) and trans-epithelial photorefractive keratectomy (T-PRK), the number of corneal laser surgeries in China has increased significantly. Although severe postoperative complications are rare, there is still the possibility of complications. Once complications occur and are not treated in time and effectively, the visual acuity and visual quality of patients would be affected. Paying attention to preoperative risk factors, standardization of the surgery procedure, and timely diagnosis and treatment of postoperative complications can minimize the negative effects. Therefore, the Cornea Group of Ophthalmology Branch of Chinese Medical Association has organized experts and scholars in this field to establish a consensus on the prevention and treatment of complications in laser corneal refractive surgery, providing guidance for the related clinical work.

[Alternative methods of surgical treatment of keratoconus]. / Al'ternativnye metody khirurgicheskogo lecheniya keratokonusa.

The introduction of early diagnostic methods for keratoconus into clinical practice has become the basis for the development of surgical treatment techniques for this pathology, such as corneal collagen crosslinking and interlamellar keratoplasty with implantation of intrastromal segments. The article analyzes the results of research by Russian and foreign specialists in these areas and presents the data on the combination of SMILE surgery and corneal crosslinking, the Rome protocol of corneal crosslinking, modifications of interlamellar keratoplasty, the use of femtosecond laser technologies, and some pilot studies. Modern requirements for ophthalmological care require a personalized approach to each patient, and therefore the surgeon should have a wide range of surgical methods of treatment applicable to different patient cohorts. The described methods of treatment, according to the authors, are the most promising.

Corneal biomechanical characteristics following small incision lenticule extraction for myopia and astigmatism with 3 different cap thicknesses.

BACKGROUND: The design of cap thickness for small incision lenticule extraction (SMILE) plays a role in post-laser vision correction (post-LVC) corneal biomechanics. This study aimed to compare the corneal biomechanical characteristics following SMILE with different cap thicknesses of 110 µm, 120 µm, and 130 µm for myopia and myopic astigmatism correction. METHODS: Seventy-five patients (146 eyes) who underwent SMILE with designed cap thickness of 110 µm, 120 µm, and 130 µm were recruited at the Eye Center of Beijing Tongren Hospital between August 2020 and November 2021. Visual acuity, refraction, and corneal biomechanical parameters were measured preoperatively, 1 week and 1, 3, 6 months postoperatively. One-way analysis of variances (ANOVA) with Bonferroni correction or Kruskal-Wallis test was performed to compare the parameters among different groups. Repeated-measures analysis of variance with Bonferroni correction or Friedman test was applied for comparing the parameters within different follow-up times. RESULTS: Uncorrected distance visual acuity of 110-µm group was better only at 1-week and 1-month postoperatively (P = 0.012, 0.037). There were no significant differences in spherical equivalent, nor in Corvis biomechanical index-laser vision correction (CBI-LVC). All the parameters reached stability at 3-month postoperatively. Integrated radius (IR) and deformation amplitude ratio 2 mm (DA ratio 2 mm) in 120-µm and 130-µm groups were higher than 110-µm group at 1-month postoperatively (P = 0.019, 0.002). So was Ambrósio relational thickness (ARTh) at 6-month postoperatively (P = 0.011). Stiffness parameter at applanation A1 (SP-A1), stress-strain index (SSI), biomechanically corrected intraocular pressure (bIOP) and central corneal thickness (CCT) were highest in 130-µm group, followed by 120-µm group, then 110-µm group at 3-month (P<0.001, P = 0.030, P = 0.027, P = 0.008) and 6-month (P<0.001, P = 0.002, P = 0.0023, P = 0.001) postoperatively. CONCLUSIONS: The corneal stiffness following SMILE was greatest with 130-µm cap, followed by 120-µm cap, then 110-µm cap. 130-µm cap might have advantages in terms of corneal biomechanics and retreatment option. The SMILE-designed protocol should be customized in practice.

Corneal remodeling after SMILE for moderate and high myopia: short-term assessment of spatial changes in corneal volume and thickness.

PURPOSE: To evaluate the early corneal remodeling and its influencing factors after Small incision lenticule extraction (SMILE) for moderate and high myopia. METHODS: This was a retrospective study. Pre- and post-operative (1 week and 1, 3, 6 months) corneal volume (CV), mean keratometry (Km), and corneal thickness (CT) were measured by Scheimpflug tomography. CT at the central, thinnest point, and on concentric circles of 2, 4, and 6 mm diameter was recorded to assess corneal thickness spatial profile (CTSP) and percentage of thickness increase (PTI) in the moderate and high myopia groups, and to explore possible influencing factors. RESULTS: After SMILE, the peripheral CT decreased in the moderate myopia group and central corneal thickness (CCT) increased in the high myopia group at 1 month compared to 1 week (all P < 0.05). The CV, Km and CT were significantly increased at 3 months compared to 1 month (all P < 0.05), but there was no significant change at 6 months compared to 3 months for both groups (all P > 0.05). Patients with high myopia showed greater corneal thickness changes (△CT) and higher PTI than moderate myopia (all P < 0.05). Regression analysis revealed that in addition to refraction, peripheral PTI was negatively correlated with CCT in the moderate myopia group (4 mm: ß = -0.023, P = 0.001; 6 mm: ß = -0.050, P < 0.001), as well as in the high myopia group (4 mm: ß = -0.038, P < 0.001; 6 mm: ß = -0.094, P < 0.001). Moreover, peripheral PTI in the moderate myopia group was negatively correlated with age (4 mm: ß = -0.071, P = 0.003; 6 mm: ß = -0.162, P < 0.001). CONCLUSIONS: After SMILE, the CV, Km, and CTSP showed dynamic changes in the early stage, which stabilized after 3 months. Compared to the moderate myopia group, the high myopia group experienced slower corneal stabilization. The change in PTI at 6 months after SMILE may be related to higher preoperative refraction, thinner CCT and younger age.

Methods of Corneal Vertex Centration and Evaluation of Effective Optical Zone in Small Incision Lenticule Extraction.

Inappropriate small incision lenticule extraction (SMILE) centration methods can affect the decentration of the effective optical zone (EOZ) after operation, which can subsequently lead to the decline of postoperative visual quality. We aimed to provide an overview of corneal vertex (CV) centration methods and an evaluation of the size and decentration of the EOZ in SMILE. We described the CV centration methods for patients with myopia, myopic astigmatism, hyperopia, and large kappa angle. The measurement methods of the EOZ were evaluated from the aspects of corneal morphology and corneal refractive power. Additionally, we summarized the advantages and disadvantages of measuring decentration based on topographic mapping and intraoperative video-captured images. Finally, we discussed the relationship between the EOZ and visual quality. Based on our review, clinicians should consider the following when choosing CV centration methods and evaluating EOZ postoperatively. First, the tear film mark center or topographic map comparison method is preferred for the correction of myopia, low myopic astigmatism, hyperopia, and large kappa angle (>0.2 mm). Triple marking centration is recommended for high myopic astigmatism (-3.5 diopters). Second, the total corneal power better reflects the change in refractive power than the topographic method. The measurement of the area rather than the diameter of the total corneal refractive power is more suitable for the evaluation of noncircular EOZs after high myopia astigmatism (<-2.0 diopters). Third, for the evaluation of decentration, the tangential curvature difference map method is preferred as it is not influenced by offset pupils. Finally, a large EOZ after SMILE may improve patient tolerance to decentration.

Grading for suction loss in small incision lenticule extraction.

INTRODUCTION: To observe the characteristics of suction loss in small-incision lenticule extraction (SMILE) and analyze the factors affecting the stability of the suction ring, classify and grade suction loss, and determine the principles for its prevention and control. METHODS: This study enrolled patients who underwent SMILE between June 2014 and June 2017. The relationship between the stability of the suction ring and suction loss was ascertained using surgical records and video recordings. The suction loss was classified and graded according to its characteristics and relationship with eye or head movement. The effect of target intervention on suction loss was observed. RESULTS: Suction loss can be divided into sudden and progressive types. According to the severity, the latter was divided into three grades (grade 1A or 1B, 2 and 3). Of the 1200 eyes (608 patients), two (0.17%) had sudden suction loss, and 132 (11%) had progressive suction loss. The superior part, inferior part, and other parts accounted for 63.4%, 19.3%, and 17.3% of progressive suction loss, respectively. The proportion of grades 1A, 1B, 2, and 3 suction loss was 53%, 34%, 12%, and 1%, respectively. The location of the threatened suction loss was opposite to the direction of the patient's head movement. After the intraoperative intervention, grades 1 and 2 did not develop into "actual" suction loss. CONCLUSIONS: Progressive suction loss was the most frequently observed suction loss during SMILE procedure. Grading suction loss can elucidate its underlying mechanism, which can guide targeted intervention measures to effectively control and reduce suction loss-induced damage, and further improve the safety and efficacy of SMILE.

SMILE lenticule versus amniotic membrane graft (AMG) augmented with platelet-rich plasma (PRP) for the treatment of perforated corneal ulcer.

PURPOSE: To evaluate the safety and efficacy of stromal lenticule obtained from small-incision lenticule extraction (SMILE) surgery versus amniotic membrane graft (AMG) augmented with platelet-rich plasma (PRP) for the treatment of perforated corneal ulcers and compare the results between the two groups. PATIENTS AND METHODS: This is a comparative retrospective study that included 40 eyes with medium-sized corneal perforations, which were classified into two equal groups of 20 eyes each; group (A) was treated with SMILE lenticule graft and group (B) was treated with AMG augmented with PRP. Pre- and postoperative evaluations were carried out using both slit-lamp (SL) examination and anterior segment optical coherence tomography (AS-OCT), including closure of perforation, complete healing, and best corrected visual acuity (BCVA). RESULTS: Complete closure of the perforation was achieved in both groups. However, healing was faster in the SMILE lenticule group than in the AMG with PRP group (P < 0.05). Complete healing was achieved in both groups: 100% in SMILE lenticule group and 95% in AMG with PRP group (P > 0.05). Both groups had few insignificant complications (30% in each), which were managed. CONCLUSION: Both methods achieved adequate healing of corneal perforations within few weeks without significant complications. However, the stromal lenticule obtained from small-incision lenticule extraction (SMILE) surgery tended to be safer with faster healing than AMG with PRP.

Subjective patient-reported visual quality after small-incision lenticule extraction and its correlation to the objective one.

PURPOSE: The purpose of the study was to characterize the subjective visual quality and satisfaction following small-incision lenticule extraction (SMILE) and to identify its influential factors. SETTING: Peking University Third Hospital, Beijing, China. DESIGN: This was a retrospective observational study. METHODS: Patients who had simultaneous binocular SMILE for myopia and myopic astigmatism were included 6 months postoperatively, and the patient-reported outcome questionnaire was employed for the assessment of visual quality in real-life situations. Examinations with SIRIUS combined corneal topography and tomography were performed including the parameters of Strehl ratio (SR), corneal higher-order aberrations (HOAs) within 6.0-mm area, kappa angel, and thinnest corneal thickness. Decentration and effective optical zone (EOZ) were measured based on a tangential pre-post-operation difference map. Binary logistic regression analysis was performed for predictors of patient-reported visual quality. RESULTS: Clinical data from 97 cases were analyzed retrospectively. Overall satisfaction was 96.91% (94/97). Fluctuation in vision and glare is the most frequent and dominant visual symptoms. SR value increased non-significantly compared with preoperative (P> 0.05). A statistically significant (P < 0.05) increase in total HOAs, spherical aberration, and coma was noted. SR and HOAs were not correlated with the degree of visual symptoms (P > 0.05). No objective parameter was found to be associated with patient-reported visual quality after SMILE (P> 0.05). CONCLUSION: The high patient-reported satisfaction confirmed the ideal effect on visual quality following SMILE in real-life situations, though some objective optical performances were not satisfying. It is very tolerant toward patients' conditions and mild deviations, and this study did not find factors affecting visual performances.