Article

Influence of Preoperative Astigmatism Type and Magnitude on the Effectiveness of SMILE Correction

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Abstract

PURPOSE: To assess the effectiveness of small incision lenticule extraction (SMILE) as a function of the astigmatism level and type. METHODS: A total of 102 right eyes were included in this study. Refractive astigmatism and corneal astigmatism measured with Scheimpflug technology were retrieved from the preoperative visit and the 3-month follow-up visit. Patients were split into three groups according to the preoperative refractive astigmatism (0.50, 0.75 to 1.25, and 1.50 diopters [D] or greater) and the effectiveness among each group was evaluated according to the with-the-rule (WTR), against-the-rule (ATR), and oblique classifications. The standard Alpins method was used for the analysis. RESULTS: Resultant astigmatism was not associated with its preoperative classification when the total sample was considered, but a significant association emerged between the presence of resultant astigmatism and its preoperative classification in the 1.50 D or greater group. The magnitude of error was significantly lower in the WTR (median: -0.30 D) than in the oblique and ATR astigmatism groups, resulting in a coefficient of adjustment of 1.13 for WTR astigmatism of 1.50 D or greater but not for the other types. CONCLUSIONS: Astigmatism correction with SMILE is predictable for astigmatism lower than 1.50 D without the need to apply a correction. However, higher undercorrection is present in WTR astigmatism of 1.50 D or greater.

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... D), and similar trends of undercorrecting higher amounts of astigmatism and overcorrecting lower amounts have been reported in other studies ( Figure 3). 31,32 When stratified by preoperative cylinder at twelve months, there was 4% undercorrection for eyes with <−1.00D of astigmatism (n=11), 10% in eyes with ≥−1.00 D to −2.00 D (n=14), and 17% in eyes with ≥−2.00 D (n=7). At twelve months, the FDA reported overall astigmatism undercorrection of 4% versus this study's finding of 10%. ...
... 11 Undercorrection reported in previous studies ranges from around 10-15% which is in agreement with our study. [8][9][10]12,[31][32][33][34] A benefit of vector analysis over the use of MSE in astigmatic outcomes is appreciating the changes in the axis of astigmatism. Inadequate adjustment for cyclotorsion leads to increasing angles of error and potentially poorer visual outcomes. ...
... 36,37 An association between with-the-rule (WTR) astigmatism and undercorrection, when compared to against-therule (ATR) or oblique astigmatism, has been well described. 31,32 This was also observed in our study as geometric means of CI in eyes with WTR astigmatism (0.85 at three months and 0.78 at twelve) were lower than those seen in eyes with ATR (1.15 and 1.36) or oblique (1.25 and 1.05) astigmatism. This signifies that at twelve months, WTR eyes (n=21) were undercorrected by 22% and ATR eyes (n=5) were overcorrected by 36%. ...
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Purpose: To assess a single site's initial experience with SMILE for the treatment of myopic astigmatism and compare outcomes and vector analysis results with the US Food and Drug Administration (FDA) results and published literature. Patients and methods: Forty-eight eyes (29 patients) with mean preoperative sphere of -5.11 ± 1.31 diopters (D) and cylinder of -1.12 ± 0.60 D underwent SMILE. Visual acuity, refractive, and vector analysis outcomes as well as subjective measures were reported at three and twelve months postoperatively and compared with FDA results and the published literature between 2014 and 2020 involving treatment of patients with mean cylinders of >-0.50 to ≤-3.00 D. Results: At three and twelve months, 43 and 32 eyes were evaluated, respectively. At twelve months, mean cylinder power was reduced to -0.38 ± 0.38 D with 78.1% achieving ≤±0.50 D. Uncorrected distance visual acuity (UDVA) ≥20/20 was achieved in 77.4% of eyes by twelve months with 100% achieving ≥20/30 UDVA. No loss of corrected distance visual acuity was observed in eyes seen at twelve months. Correction index (CI) at twelve months was 0.90 indicating overall undercorrection of 10%. Twelve-month CI was 0.96, 0.90, and 0.83 in eyes with preoperative cylinders of <-1.00 D, ≥-1.00 to <-2.00 D, and ≥-2.00 D, respectively. Mean angle of error was -1.58 ± 11.61° ranging from -24.22° to 37.75°. Conclusion: We found SMILE to be an effective and safe means of achieving spectacle independence and improving visual acuity in patients with myopic astigmatism. SMILE has the potential for improved clinical outcomes with better nomogram guidance and advancements in technique. However, surgeons must be aware of the potential for undercorrection in with-the-rule astigmatism and at higher preoperative cylinders and as well as the potential for overcorrection in against-the-rule and lower preoperative cylinder astigmatism.
... An island after laser corneal refractive surgery can be defined as an area within a treatment zone that is steeper in curvature than the surrounding cornea. 1 These islands are usually reported as central islands because they are generally presented as a well-circumscribed circular or oval area in the center of the treatment zone. 1 Small Incision Lenticule Extraction (SMILE), with first results reported in 2011 2 and approved by FDA for simple myopia in late 2016, 3 has demonstrated to be safe, accurate, effective and stable 4 for myopia 5 and astigmatism 6 corrections although the application of a nomogram can be required to optimize results in some cases. 5,7,8 Complications have been also reported including some perioperative such as suction loss, incisional bleeding, tears, cap perforation, opaque bubble layer, subconjunctival hemorrhage, black areas, unintended posterior plane dissection, abrasion at the incision, inaccurate laser pulse placement due to eye movement, epithelial defects and others. ...
... Cyclotorsion was manually corrected in eyes with astigmatism equal or higher to 1.50 D by means of marking 2 mm from the limbus and manually rotating the sucking cone to match the corneal marks (the ones along the 0° to 180° line) with the reticle. 6 Finally, two drops of tobramycin (3 mg/ml) and dexamethasone (1 mg/ml) combination were instilled in all cases immediately at the end of the procedure. Postoperative treatment included ofloxacin (3 mg/ml) for 2 days, dexamethasone drops 5, 3, 2 and 1 per day tapered each 7 days, and sodium hyaluronate 0.15% for 1 month. ...
Article
Purpose: To evaluate the incidence of central islands after 6-month follow-up of Small Incision Lenticule Extraction (SMILE) and to assess their role in safety and accuracy. Methods: Analysis of the preoperative and postoperative corneal tomography, best spectacle refraction and corrected distance visual acuity of 82 subjects that underwent SMILE. Incidence of central islands was assessed through total corneal spherical aberration (SA) over 4 mm of central diameter and the SA was compared between two groups with and without safety loss (CDVA difference ≥0.1 logMAR from preoperative). The cut-off value for detecting the risk of postoperative central island development was calculated. The influence in accuracy was calculated through magnitude of error of the spherical equivalent and astigmatism, both for spectacle refraction at corneal plane (SE-Rx and AST-Rx) and for total corneal refractive power at 3 mm (SE-TCRP3 and AST-TCRP3). Results: Five from 82 eyes resulted in a loss of safety, obtaining significant differences in SA, both preoperatively (p = .01) and postoperatively (p = .007) after stratification by safety loss. A preoperatively cut-off value ≤0.012 μm of SA predicted the appearance of central islands with sensitivity of 100% and specificity of 75%. Despite postoperative SA being related to the preoperative spherical equivalent, for both SE-Rx and SE-TCRP3, this tendency disappeared after readjusting results according to a nomogram. Conclusions: Central islands in SMILE, despite being a rare adverse event, can affect the safety of the procedure and are related to preoperative central steepness, not corrected by the spherical lenticule, which is clearly visible postoperatively.
... High astigmatism has also been observed to be consistently undercorrected, even with the FLEx procedure (femtosecond laser extraction: with a flap), which predates SMILE. In a retrospective series of 102 eyes, Pérez-Izquierdo observed that more-aggressive management was required for with-the-rule (WTR) astigmatism greater than 1.50 D, observing a 13% undercorrection of WTR astigmatism [40]. Similarly, DRH nomogram adds 15% to WTR astigmatic corrections and no additional correction for against the rule astigmatism. ...
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Purpose of Review In this article, we review the early experience with small incision lenticule extraction (SMILE) in the USA as well as recent international data. We address long-term experience, new techniques, optimization of settings, corneal biomechanics, and comparison with other refractive surgical procedures. Recent Findings Despite promising early experience, US refractive surgeons have adopted the SMILE procedure slowly, owing in part to limitations on energy settings that have impacted early visual recovery. Outside of the USA, advances in parameters and techniques have driven improved early and long-term outcomes, with the result of increasing adoption. Although there remains debate, there is evidence for parity with FS-LASIK in visual outcomes, as well as advantages to SMILE in post-operative dry eye, spherical aberration induction, and biomechanical stability. Summary SMILE is a safe and effective procedure with promising advantages over other techniques and increasing usership worldwide. Continued improvements in energy optimization, nomogram development, and surgical technique allow for improved outcomes over early iterations of SMILE.
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Purpose: To evaluate the influence of patient's age at the time of surgery on small incision lenticule extraction (SMILE) refractive outcomes. Methods: This 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. Results: 102 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. Conclusions: Post-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.
Article
Introduction: Lenticule extraction refractive procedures have emerged as a capable alternative to excimer laser based correction procedures, with many associated advantages. At the same time, this technique lacks automated centration and cyclotorsion control, resulting in several concerns regarding its capability to correct moderate or high levels of astigmatism, potentially resulting in higher residual refraction postoperatively compared to excimer laser based refractive corrections. Areas Covered: Using PubMed with keywords ‘SMILE’ and ‘astigmatism’, the objective of this paper is to review the reported outcomes of lenticule extraction refractive procedures for the correction of myopic astigmatism, and compare them to the excimer laser-based corneal refractive surgery techniques. The inclusion criterion was strict relevance and adequacy to the clinical questions under research, and availability of the abstract in English language. Expert Opinion/Commentary: From scientific literature reviewed in this article, lenticule extraction procedures were found to produce satisfactory visual outcomes in terms of safety, efficacy and predictability. The technique is also predictable and effective for astigmatic corrections, but could present with undercorrections especially for higher refractive corrections. Manual cyclotorsion error compensation and triple marking centration methods are capable additions to the technique in improving outcomes for high astigmatism corrections, compared to conventional subjective patient fixation.
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Purpose: To analyze residual refractive error, ocular aberrations and visual acuity during accommodation simultaneously with ocular aberrometry in post-LASIK, SMILE and TransPRK eyes Methods: Ocular aberrometry (Tracey Technologies, USA) was performed 3 months after LASIK (n=95), SMILE (n=73) and TransPRK (n=35) eyes. While measuring the aberrations, visual acuity (VA) was measured at a distance (20 ft), intermediate (60 cm) and near (40 cm) targets. The examinations were done monocularly. A parallel group of age matched normal eyes (n=50) with subjective 6/6 distance VA also underwent aberrometry. Results: Distribution of residual spherical error of LASIK eyes matched the normal eyes the best, followed by SMILE and TransPRK. However, distribution of cylindrical error of the SMILE eyes was distinctly different from the rest (p<0.05). The SMILE eyes tended to be undercorrected by ~0.25D on an average at all reading targets compared to LASIK (p<0.05). The undercorrection was greater, when the magnitude of preoperative cylinder exceeded -0.75D (p<0.05). The VA of LASIK and SMILE eyes were similar to normal eyes at all targets but the TransPRK eyes were marginally inferior (p<0.05). Only the ocular defocus changed differentially between the study groups during accommodation and the magnitude of change was least for TransPRK eyes (p<0.05). However, postoperative near and intermediate accommodation of LASIK eyes were similar to the normal eyes, followed by SMILE and then TransPRK. Conclusions: The status of the LASIK eyes was closest to the normal eyes postoperatively. The SMILE procedure may benefit with slight overcorrection of preoperative refractive cylinder.
Article
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Small Incision Lenticule Extraction (SMILE) is a flap-free intrastromal technique for the correction of myopia and myopic astigmatism. To date, this technique lacks automated centration and cyclotorsion control, so several concerns have been raised regarding its capability to correct moderate or high levels of astigmatism. The objective of this paper is to review the reported SMILE outcomes for the correction of myopic astigmatism associated with a cylinder over 0.75 D, and its comparison with the outcomes reported with the excimer laser-based corneal refractive surgery techniques. A total of five studies clearly reporting SMILE astigmatic outcomes were identified. SMILE shows acceptable outcomes for the correction of myopic astigmatism, although a general agreement exists about the superiority of the excimer laser-based techniques for low to moderate levels of astigmatism. Manual correction of the static cyclotorsion should be adopted for any SMILE astigmatic correction over 0.75 D.
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Background This study aimed to determine and validate that use of a nomogram could enhance the predictability of small-incision lenticule extraction (SMILE) surgery. Material/Methods 195 eyes from 98 patients were enrolled in group 1, and 46 eyes from 26 patients in group 2. Uncorrected and corrected distance visual acuity (UDVA and CDVA), manifest refraction spherical equivalent (SE) preoperatively and 1 day, 1 week, 1 month, and 3 months postoperatively were measured. A nomogram based on the error in SE correction was generated by using multifactor regression method in group 1. After applying this nomogram to redesign the refraction target, the predictability, safety, and efficacy of the SMILE procedure were determined. Results A linear regression formula (SE error=0.259+0.113×SEpreoperative) was derived as a nomogram to adjust the SE target. In group 2, the predictability of error was 86.21% within 0.50 D and 97.83% within 1.00 D, compared with 70.25% and 95.90%, respectively, in group 1. The use of the nomogram significantly reduced the variance in postoperative SE. The efficacy and safety of SMILE did not differ significantly in the 2 groups 3 months postoperatively. Conclusions The nomogram can optimize the target refractive prediction of the SMILE procedure without compromising safety and efficiency.
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Purpose. To assess the amount and the axis orientation of anterior and posterior corneal astigmatism after refractive lenticule extraction (ReLEx) for myopic astigmatism. Methods. We retrospectively examined 53 eyes of 53 consecutive patients (mean age ± standard deviation, 33.2 ± 6.5 years) undergoing ReLEx to correct myopic astigmatism (manifest cylinder = 0.5 diopters (D)). Power vector analysis was performed with anterior and posterior corneal astigmatism measured with a rotating Scheimpflug system (Pentacam HR, Oculus) and refractive astigmatism preoperatively and 3 months postoperatively. Results. Anterior corneal astigmatism was significantly decreased, measuring 1.42 ± 0.73 diopters (D) preoperatively and 1.11 ± 0.53 D postoperatively (p < 0.001, Wilcoxon signed-rank test). Posterior corneal astigmatism showed no significant change, falling from 0.44 ± 0.12 D preoperatively to 0.42 ± 0.13 D postoperatively (p = 0.18). Refractive astigmatism decreased significantly, from 0.92 ± 0.51 D preoperatively to 0.27 ± 0.44 D postoperatively (p < 0.001). The anterior surface showed with-the-rule astigmatism in 51 eyes (96%) preoperatively and 48 eyes (91%) postoperatively. By contrast, the posterior surface showed against-the-rule astigmatism in all eyes preoperatively and postoperatively. Conclusions. The surgical effects were largely attributed to the astigmatic correction of the anterior corneal surface. Posterior corneal astigmatism remained unchanged even after ReLEx for myopic astigmatism.
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Purpose: To compare postoperative astigmatic correction between femtosecond lenticule extraction (FLEx) and small-incision lenticule extraction (SMILE) in eyes with myopic astigmatism. Methods: We examined 26 eyes of 26 patients undergoing FLEx and 26 eyes of 26 patients undergoing SMILE to correct myopic astigmatism (manifest astigmatism of 1 diopter (D) or more). Visual acuity, cylindrical refraction, the predictability of the astigmatic correction, and the astigmatic vector components using Alpin's method, were compared between the two groups 3 months postoperatively. Results: We found no statistically significant difference in manifest cylindrical refraction (p=0.74) or in the percentage of eyes within ± 0.50 D of their refraction (p=0.47) after the two surgical procedures. Moreover, no statistically significant difference was detected between the groups in astigmatic vector components, namely, surgically induced astigmatism (0.80), target induced astigmatism (p=0.87), astigmatic correction index (p=0.77), angle of error (p=0.24), difference vector (p=0.76), index of success (p=0.91), flattening effect (p=0.79), and flattening index (p=0.84). Conclusions: Both FLEx and SMILE procedures are essentially equivalent in correcting myopic astigmatism using vector analysis, suggesting that the lifting or non-lifting of the flap does not significantly affect astigmatic outcomes after these surgical procedures.
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To evaluate the refractive outcomes for the correction of low to moderate astigmatism up to 1 year following small incision lenticule extraction (SMILE) surgery. This retrospective study enrolled 98 eyes from 98 patients who underwent SMILE surgery for the correction of myopia and astigmatism. Only right eyes were included in this study to avoid the bias of orientation errors. The vector method was used to analyze the outcomes of astigmatism at 1 month, 6 months and 12 months after the procedure, including the double-angle plots, correction index (CI), index of success (IOS), angle of error (AofE) and magnitude of error (MofE). The effectiveness, safety, stability and predictability were also investigated during the 12-month follow-up. The preoperative cylinder ranged from -2.75 D to -0.25 D (average of -0.90 +/- 0.68 D), and the mean postoperative cylinder values were -0.24 +/- 0.29 D, -0.24 +/- 0.29 D, and -0.20 +/- 0.27 D at 1 month, 6 months, and 12 months, respectively. The mean astigmatism in vector form was -0.14 D x 27.19[degree sign] at 1 month, -0.13 D x 27.29[degree sign] at 6 months, and -0.10 D x 28.63[degree sign] at 12 months after surgery. The CI was 1.00 +/- 0.32 and IOS was 0.29 +/- 0.44 at the 12-month follow-up. Significant negative correlations were found between the CI and absolute target induced astigmatism (TIA) value, and positive correlations were found between the IOS and absolute AofE value (P < 0.05). The MofE was limited within +/-1.00 D at the 12-month follow-up. Fifty-six eyes (57.1%) gained one line in corrected distance visual acuity (CDVA) and five eyes (5.1%) gained two lines. There were no significant differences observed in the refractive outcomes among time points. SMILE surgery was effective and safe in correcting low to moderate astigmatism, and stable refractive outcomes were observed at the long-term follow-up. The undercorrection of astigmatism could possibly be influenced by attempted astigmatism correction preoperatively, the axis rotation during the surgery or wound healing postoperatively. This study suggested that nomograms should be adjusted in correcting astigmatism with SMILE surgery.
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To compare postoperative astigmatic correction between femtosecond lenticule extraction (FLEx) and wavefront-guided LASIK in eyes with myopic astigmatism. Fifty-eight eyes of 41 patients undergoing FLEx and 49 eyes of 29 patients undergoing wavefront-guided LASIK to correct myopic astigmatism were examined. Visual acuity, cylindrical refraction, predictability of the astigmatic correction, and astigmatic vector components were compared between groups 6 months after surgery. There was no statistically significant difference in manifest cylindrical refraction (P = .08) or percentage of eyes within ±0.50 diopter (D) of its refraction (P = .11) between the surgical procedures. The index of success in FLEx was statistically significantly better than that of wavefront-guided LASIK (P = .02), although there was no significant difference between the groups in other indices (eg, surgically induced astigmatism, target-induced astigmatism, astigmatic correction index, angle of error, difference vector, and flattening index). Subgroup analysis showed that FLEx had a better index of success (P = .02) and difference vector (P = .04) than wavefront-guided LASIK in the low cylinder subgroup; the angle of error in FLEx was significantly smaller than that of wavefront-guided LASIK in the moderate cylinder subgroup (P = .03). Both FLEx and wavefront-guided LASIK worked well for the correction of myopic astigmatism by the 6-month follow-up visit. Although FLEx had a better index of success than wavefront-guided LASIK when using vector analysis, it appears equivalent to wavefront-guided LASIK in terms of visual acuity and the correction of astigmatism. [J Refract Surg. 2014;30(12):806-811.]. Copyright 2014, SLACK Incorporated.
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Background To report our experience with small incision lenticule extraction ("SMILE") for myopia treatment. Methods In this prospective clinical study, we evaluated 447 eyes from 224 patients with myopia, with and without astigmatism. We followed the patients for 6 months after SMILE. Results The mean (±standard deviation, SD) spherical equivalent was -6.75 ± 1.65 diopters (D) preoperatively and -0.21 ± 0.37 D at 6 months postoperatively. Our data showed that 97.9% of eyes were within ±1.0 D and 86.1% were within ±0.5 D of the intended correction. Furthermore, 79.8% had an uncorrected distance visual acuity (UDVA) of 0 logMAR or less (20/20 or better in the Snellen equivalent) 6 months after surgery. Additionally, 48.5% remained unchanged, 41% gained one line of corrected distance visual acuity (CDVA), 7.2% gained two lines of CDVA, 3.3% lost one line of CDVA, and 0.3% lost two or more lines of CDVA. Age was the only predictor for worsening UDVA at 6 months postoperatively in linear regression analyses (0.07 decrease logMAR per increased 10 years of age; P < 0.05). No predictor showed an association with error in spherical equivalent refraction at 6 months postoperatively. Conclusions SMILE is an effective and safe refractive surgery. Age was the only predictor that influenced visual outcome, but its effect appeared clinically insignificant. Faster visual recovery is also expected with improved surgical technique.
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To determine the effectiveness of correcting astigmatism by laser refractive surgery by a vectorial astigmatism outcome analysis that uses 3 fundamental vectors: target induced astigmatism vector (TIA), surgically induced astigmatism vector, and difference vector, as described by the Alpins method. A data set of 100 eyes that had laser in situ keratomileusis to correct myopia and astigmatism (minimum preoperative refractive astigmatism 0.75 diopter) was analyzed. The data included preoperative and 3 month postoperative values for manifest refraction and standard keratometry. Using the ASSORT or VectrAK analysis program, individual and aggregate data analyses were performed using simple, polar, and vector analysis of astigmatism and an analysis of spherical change. Statistical analysis of the results was used for means and confidence limits, as well as to examine the differences between corneal and refractive astigmatism outcomes. At an individual patient level, the angle of error was found to be significant, suggesting variable factors at work, such as healing or alignment. A systematic error of undercorrection of astigmatism is prevalent in the treatment of these 100 patients by a factor of between 15% and 30%, depending on whether refractive or corneal values are examined. Spherical correction showed systematic undercorrection of 11%, and parallel indices demonstrated it to be more effective than the astigmatic correction. This method of astigmatism analysis enables the examination of results of astigmatism treatment measured by both refractive and corneal measurements using vector analysis. By examining individual vector relationships to the TIA (ie, the correction index, index of success, and flattening index), a comprehensive astigmatism analysis is completed. Each index provides information necessary for understanding any astigmatic change. Astigmatic outcome parameters are more favorable when measured by subjective refractive than objective corneal methods.
Article
Purpose: Dry eye is known to impact on clinical outcomes after laser vision correction and the use of a newer 'all femtosecond laser' surgical approach may be associated with less impact on the ocular surface post-operatively. The purpose of this study was to evaluate the early clinical outcomes and tear instability after the first small incision lenticule extraction (SMILE) cases undertaken by three surgeons at a single site in the UK. Methods: Retrospective audit. Seventy-one eyes of 37 patients underwent SMILE surgery using the Zeiss VisuMax laser system (Carl Zeiss Meditec, Germany). Uncorrected and corrected distance visual acuity, spherical equivalent refraction, fluorescein enhanced tear break up time, simulated keratometry and complications were evaluated pre- and post-operatively where applicable. Results: The study population consisted of 21 males and 16 females. The mean±standard deviation age was 33±8years. The results showed that 100% of eyes achieved 20/40 or better and 88% achieved 20/20 or better uncorrected distance visual acuity. The spherical equivalent refraction after surgery was within ±0.50D in 82% of eyes at three months. There was no significant difference in tear break up time from pre-operative levels at three months. Complications were infrequent. Conclusions: This early data from surgeons' first SMILE procedures suggest SMILE provides good outcomes in terms of refractive predictability and visual acuity with minimal impact on the tear film. Longitudinal research will further improve our understanding of the longer-term impact of SMILE on clinical outcomes, ocular surface metrics and patient reported outcomes.
Article
Purpose To evaluate and compare the efficacy of the astigmatic correction after wavefront-guided laser in situ keratomileusis (LASIK) and small-incision lenticule extraction (SMILE) and in myopic eyes. Design Prospective case series. Setting Horus Vision Correction Center and Ellite Vision Correction Center, Alexandria, Egypt. Methods Myopic eyes with astigmatism up to 4.00 diopters (D) had wavefront-guided LASIK or small-incision lenticule extraction. Visual and refractive changes were evaluated during a 6-month follow-up. The astigmatic changes were evaluated using the Alpins method. Result The study evaluated 107 eyes (55 patients), 52 eyes having wavefront-guided LASIK and 55 eyes, small-incision lenticule extraction. No statistically significant differences were found in the 6-month postoperative sphere between the 2 groups (P = .652). The postoperative manifest cylinder and spherical equivalent were significantly lower in the wavefront-guided LASIK group (P < .001). The 6-month postoperative cylinder was 0.50 D or less in all eyes in the wavefront-guided LASIK groups and in 79.8% in the small-incision lenticule extraction group (P < .001). Vector analysis showed a significantly higher difference vector (P < .001) and angle of error (P = .021) and a significantly lower correction index (P = .001) in the small-incision lenticule extraction group. The mean magnitude of error was −0.07 ± 0.20 (SD) and −0.20 ± 0.35 in the wavefront-guided LASIK group and small-incision lenticule extraction group, respectively (P = .012). Conclusion Wavefront-guided LASIK and small-incision lenticule extraction were safe and effective for the correction of myopic astigmatism, although there was a trend toward undercorrection with small-incision lenticule extraction.
Article
Purpose: To compare safety and efficacy of topography-guided LASIK and contralateral eye SMILE for myopia and myopic astigmatism correction. Methods: This prospective, randomized contralateral eye study included 44 eyes of 22 patients with bilateral myopia or myopic astigmatism. Treated eyes were divided into two groups: 22 eyes were treated with topography-guided LASIK and the fellow eye of each patient was treated with SMILE. The following parameters were evaluated preoperatively and up to 3 months postoperatively: uncorrected distance vision acuity (UDVA), corrected distance vision acuity (CDVA), refractive error, corneal keratometry, contrast sensitivity, and Objective Scatter Index. Results: At 3 months, 86.4% of the LASIK group and 68.2% of the SMILE group had UDVA of 20/20 (P < .002) and 59.1% and 31.8%, respectively, had UDVA of 20/16 (P < .002). Spherical equivalent refraction (±0.50 D) was 95.5% for the LASIK group and 77.3% for the SMILE group (P < .002). Residual refraction cylinder (≤ 0.25 D) was 81.8% for the LASIK group and 50% for the SMILE group (P < .001). Contrast sensitivity (6 cycles/degree) was 7.2 ± 1.01 in the LASIK group and 6.20 ± 1.52 in the SMILE group. Objective Scatter Index measurements at 3 months were 1.35 in the LASIK group and 1.42 in the SMILE group. Conclusions: Topography-guided LASIK was superior in all visual performance parameters studied, both subjective and objective. The main difference between the two techniques likely derives from the eye tracking, cyclorotation compensation, and active centration control in the LASIK technology studied in contrast to the current technology available with SMILE-like procedures. This difference appears to affect refractive and visual aberration performance outcomes. [J Refract Surg. 2017;33(5):306-312.].
Article
Purpose: To report the incidence, risk factors, and outcomes of enhancement after small-incision lenticule extraction (SMILE). Design: Retrospective cohort study. Participants: Five hundred twenty-four eyes of 307 patients who underwent SMILE at Singapore National Eye Center between February 2012 and March 2016. Methods: The data collected included patient age at primary SMILE, gender, race, preoperative and postoperative manifest refraction spherical equivalent (MRSE), preoperative and postoperative uncorrected distance visual acuity and corrected distance visual acuity, the occurrence of suction loss during the procedure, and the need for enhancement. All enhancements were carried out by performing an alcohol-assisted photorefractive keratectomy (PRK) procedure with application of mitomycin C (MMC). Main outcome measures: Incidence, prevalence, preoperative and intraoperative risk factors for enhancement, and outcomes after enhancement. Results: The prevalence of enhancement was 2.7%, and 71.4% eyes had enhancement within 1 year of primary SMILE. The incidence of enhancement was 2.1% and 2.9% at 1 and 2 years, respectively. Age older than 35 years, preoperative MRSE more than -6.00 diopters (D), preoperative myopia more than 6.00 D, preoperative astigmatism more than 3.00 D, and intraoperative suction loss were significant risk factors for enhancement after SMILE after adjusting for all other covariates (odds ratios, 5.58, 4.80, 1.41, 3.06, and 2.14, respectively; P = 0.004, 0.021, 0.022, 0.002, and 0.020, respectively). In the patients who underwent bilateral SMILE, the first-operated eye had a marginal trend toward significance for enhancement (P = 0.054). There was no gender or racial difference. In the 14 eyes requiring enhancement, the uncorrected distance visual acuity before enhancement ranged from 20/80 to 20/25, and the mean attempted enhancement spherical equivalent was -0.50±0.86 D. The uncorrected distance visual acuity improved in most patients (92.9%) after enhancement. Conclusions: The 2-year incidence of enhancement after SMILE was 2.9%. Risk factors associated with enhancement included older age at SMILE procedure, greater preoperative MRSE, greater preoperative myopia, greater preoperative astigmatism, and the occurrence of intraoperative suction loss. Clinical outcomes of using PRK with application of MMC for enhancement were good.
Article
Purpose: To evaluate 12-month changes in refraction, visual outcome, corneal densitometry, and postoperative aberrations after small incision lenticule extraction (SMILE) for myopic astigmatism. Methods: This 12-month prospective clinical trial comprised 101 eyes (101 patients) treated with SMILE for myopic astigmatism with cylinder of 0.75 to 4.00 diopters (D). The preoperative, 1-week, and 1-, 3-, 6-, 9-, and 12-month examinations included measurement of manifest refraction, uncorrected distance visual acuity (UDVA), and corrected (CDVA) distance visual acuity. Astigmatic error vector analysis was performed using Al-pin's method. Densitometry and aberrations were evaluated with Pentacam HR (Oculus Optikgeräte, Wetzlar, Germany). Results: Preoperative spherical equivalent averaged -6.78 ± 1.90 D with 1.81 ± 1.00 D in cylinder correction. After 12 months, 74% and 93% of the eyes were within ±0.50 and ±1.00 D of the attempted refraction, respectively. The logMAR UDVA and CDVA averaged 0.03 ± 0.16 and -0.08 ± 0.09, respectively. Vector analysis showed a with-the-rule undercorrection at 12 months with a mean difference vector of 0.31 D @ 91°. There was a minor counterclockwise rotation of the axis, with an arithmetic angle of error of 0.34° ± 14°. An undercorrection of approximately 11% per diopter of attempted correction was seen at 12 months. Spherical aberrations, coma, and higher order aberrations remained stable during the postoperative period (P < .09). After 12 months, no increase in densitometry could be identified. Conclusions: Treatment of astigmatism with SMILE seems to be predictable and effective, but with an astigmatic undercorrection of approximately 11% and a small counterclockwise rotation of the axis. [J Refract Surg. 2017;33(1):11-17.].
Article
Purpose To determine the safety, efficacy, and predictability of small-incision lenticule extraction at 6-month follow-up, depending on the level of the myopic refractive error. The surgeries were performed by a surgeon new to this technique. Methods Seventy-one subjects with a mean age of 31.86 ± 5.57 years were included in this retrospective observational study. Subjects were divided into 3 groups depending on the preoperative spherical equivalent (SE): low group from -1.00 D to -3.00 D, medium from -3.25 D to -5.00 D, and high from -5.25 D to -7.00 D. Manifest refraction, corrected distance visual acuity (CDVA), and uncorrected distance visual acuity (UDVA) were measured before surgery and at 6 months after the treatment. Results In total, 1.4% of the eyes lost 1 line of CDVA after the procedure, whereas 95.8% remained unchanged and 2.8% gained 1 line. A significant undercorrection (p = 0.031) was found in the high myopia group (median -0.50 D), whereas the low and medium groups remained near to emmetropia. In terms of efficacy, no statistically significant intergroup differences for postoperative UDVA (p = 0.282) were found. The vector analysis also showed undercorrection of the preoperative cylinder, even though the standard deviations decreased from 0.9 D in the x axis and 0.7 D in the y axis to 0.24 D and 0.27 D, respectively. Conclusions Small-incision lenticule extraction might be a safe, effective, and predictable procedure even for inexperienced surgeons. No differences in efficacy were found among myopia levels even though undercorrections were found for SE and cylinder in high myopia.
Article
Purpose To compare the efficacy of correcting myopic astigmatism with femtosecond laser small-incision lenticule extraction (SMILE, Carl Zeiss Meditec AG) versus laser-assisted subepithelial keratectomy (LASEK). Setting The study was conducted at the Ophthalmology Department, Eye and ENT Hospital, Shanghai, China. Design A retrospective, cross-sectional study. Methods This study included patients who underwent small-incision lenticule extraction or LASEK for the correction of myopia and myopic astigmatism. Preoperative and 6-month postoperative astigmatism values were analyzed. The efficacies of the 2 surgeries to correct astigmatism were compared. Results A total of 180 right eyes of 180 patients (small-incision lenticule extraction: n = 113, LASEK: n = 67) were included. No significant difference was found between the 2 groups in the preoperative astigmatism (small-incision lenticule extraction: 1.16 ± 0.85D, LASEK: 1.16 ± 0.83D, P > .05) or the postoperative astigmatism (small-incision lenticule extraction: 0.35 ± 0.37D; LASEK: 0.31 ± 0.42D, P > .05), determined by manifest refraction. No significant difference was found between the 2 groups in surgically induced astigmatism vector (small-incision lenticule extraction: 1.13 ± 0.83D, LASEK: 1.01 ± 0.65D, P > .05). The correction index was higher for the small-incision lenticule extraction group (1.05 ± 0.53) than for the LASEK group (0.95 ± 0.21, P = .045). The postoperative astigmatism was significantly higher for the small-incision lenticule extraction group when the preoperative astigmatism was 1.0 D or less (small-incision lenticule extraction: 0.26 ± 0.30D, LASEK: 0.12 ± 0.20D, P = .007) and lower for the small-incision lenticule extraction group when the preoperative astigmatism was more than 2.0 D (small-incision lenticule extraction: 0.48 ± 0.37D, LASEK: 0.89 ± 0.46D, P = .002). Conclusions An adjustment of nomograms for correcting low astigmatism (≤1.0 D) by small-incision lenticule extraction is suggested due to the tendency toward overcorrection, whereas a nomogram adjustment for tissue-saving ablation profile is needed for the correction of high astigmatism (>2.0 D) by LASEK due to the tendency toward undercorrection. Financial Disclosure The authors declare that they have no competing financial interests.
Article
Purpose: To study the feasibility of performing myopic femtosecond small incision lenticule extraction (SMILE) with four different cap thicknesses (130, 140, 150, and 160 μm). Methods: In this retrospective, comparative, non-randomized clinical trial, a refractive lenticule of intrastromal corneal tissue was cut with the VisuMax femtosecond laser system (Carl Zeiss Meditec AG, Jena, Germany) using different depths of the non-refractive lenticule cut. Manifest refraction, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and Objective Scattering Index (OSI) were evaluated. Minimum follow-up time was 1 year. Results: Ninety-four eyes of 47 patients with myopia with (14 patients) and without (33 patients) astigmatism were treated. One year after the surgery, mean log-MAR UDVA, logMAR CDVA, SE, and OSI were 0.07 ± 0.12, 0.01 ± 0.37, 0.07 ± 0.57, and 0.88 ± 0.17, respectively (P < .05). There were no significant statistical differences in logMAR UDVA, logMAR CDVA, SE, or OSI (P > .05) variables when the different groups were compared for the same periods of time. Conclusions: No differences in visual acuity, refractive outcomes in optical visual quality, or complications were observed when using SMILE at four different depths. [J Refract Surg. 2015;31(9):580-585.].
Article
To compare the effect of a rotating microkeratome (M2) and a linear microkeratome (SBK) on the change in the astigmatic component in eyes with preoperative plano refractive cylinder. University Medical Centre Hamburg-Eppendorf, Hamburg, Germany. Retrospective case series. An Allegretto excimer laser was used to perform laser ablation in myopic eyes of consecutive patients. The laser in situ keratomileusis (LASIK) procedure included mechanical flap preparation using a microkeratome, either a linear type with a single-use 90 μm head to create a nasal hinge or a rotating type with a single-use 90 μm head to create a superior hinge. The Alpins vector method was applied to describe the effects of LASIK on postoperative refractive cylinder. The study evaluated 1045 eyes of 852 patients. Although the mean overall efficacy and safety indices indicate the procedure was highly precise, safe, and efficient, there were statistically significant differences in surgically induced astigmatism (SIA) between the microkeratomes (P = .002). The postoperative refractive cylinder (ie, SIA) was 0.75 diopter (D) or more in 116 eyes (11.1%), 44 (12.8%) of 344 linear cases and 72 (10.3%) of 701 rotating cases. Independent of the type of microkeratome used, the SIA was slightly higher in eyes treated first; the mean magnitude of the induced astigmatism was 0.35 D. In approximately 10% of eyes with preoperative plano refractive myopia, the astigmatic component tended to be overcorrected. Nevertheless, independent of the type of microkeratome, the maximum mean magnitude of refractive cylinder documented was 0.35 D. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
Article
To report the visual and refractive outcomes of small incision lenticule extraction for low myopia using the VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany). A retrospective analysis of 120 consecutive small incision lenticule extraction procedures was performed for low myopia. Inclusion criteria were preoperative spherical equivalent refraction up to -3.50 diopters (D), cylinder up to 1.50 D, and corrected distance visual acuity of 20/20 or better. Outcomes analysis was performed for all eyes with 1-year follow-up according to the Standard Graphs for Reporting Refractive Surgery, and also including mesopic contrast sensitivity. One-year data were available for 110 eyes (92%). Preoperatively, mean spherical equivalent refraction was -2.61 ± 0.54 D (range: -1.03 to -3.50 D) and mean cylinder was 0.55 ± 0.38 D (range: 0.00 to 1.50 D). Postoperatively, mean spherical equivalent refraction was -0.05 ± 0.36 D (range: -0.94 to +1.25 D) and mean cylinder was ±0.50 D in 84% and ±1.00 D in 99% of eyes. Uncorrected distance visual acuity was 20/20 or better in 96% of eyes and 20/25 or better in 100% of eyes. One line of corrected distance visual acuity was lost in 9%, but no eyes lost two or more lines. There was an initial overcorrection in mean spherical equivalent refraction on day 1 (+0.37 D) as expected, which regressed to +0.10 D at 1 month and -0.05 D at 3 months, after which stability was reached (mean spherical equivalent refraction was -0.05 D at 1 year). Contrast sensitivity at 1 year was slightly increased at 3, 6, 12, and 18 cycles per degree (P < .05). Small incision lenticule extraction for low myopia was found to be safe and effective with outcomes similar to those previously reported for LASIK. [J Refract Surg. 2014;30(12):812-818.]. Copyright 2014, SLACK Incorporated.
Article
To evaluate the outcome after small incision refractive lenticule extraction (SMILE) in patients with myopic astigmatism. Seven hundred seventy-five eyes from 403 patients with myopia treated with SMILE for a cylinder of 0.75 diopters (D) or more were identified from patient records. Six hundred sixty-nine eyes were defined as receiving low (< 2.5 D) and 106 eyes as receiving high (⩾ 2.5 D) astigmatic correction. Patients were examined before and 3 months after surgery. SMILE was performed with a Visumax femtosecond laser (Carl Zeiss Meditec, Jena, Germany). Preoperative and postoperative refractions were converted to polar values. Induced torsion and achieved corrections of sphere and cylinder were determined. In low astigmatism, the mean preoperative spherical equivalent (SE) was -7.57 ±1.67 D and the cylinder was -1.22 ± 0.49 D. Three months after surgery, SE was -0.19 ± 0.48 D from target, astigmatism was 0.17 ± 0.42 D undercorrected, and a small but significant torsion of the cylinder axis corresponding to 0.05 ± 0.37 D was found. The astigmatic undercorrection measured 13% per diopter of attempted correction. In high astigmatism, preoperative SE was -5.91 ± 2.56 D and cylinder was -3.22 ± 0.67 D. After surgery, the average astigmatic undercorrection was 0.59 ± 0.65 D, equivalent to 16% per diopter of attempted correction. No undercorrection in SE occurred and no torsion was found. SMILE in myopic astigmatism offers predictable correction of SE, but a small, significant undercorrection of the astigmatic error. The undercorrection increases with the attempted treatment. Only very little rotation of the cylinder axis was found. [J Refract Surg. 2014;30(4):240-247.].
Article
To evaluate the safety and complications of small-incision lenticule extraction (SMILE). Clinical control cohort study. A total of 922 healthy patients (1800 eyes) who were treated for myopia or myopic astigmatism between January 2011 and March 2013 at the Department of Ophthalmology, Aarhus, Denmark. Patients received a full preoperative examination and were treated with SMILE in both eyes and followed for 3 months (1574 eyes). Patients with complications, including loss of corrected distance visual acuity (CDVA) or dissatisfaction, were offered a late reexamination. Surgical complications and CDVA. Mean preoperative spherical equivalent refraction was -7.25±1.84 diopters (D). Average postoperative refraction was -0.28±0.52 D, and mean error of treatment was -0.15±0.50 D. By 3 months, 86% (1346 eyes) had unchanged or improved CDVA. A loss of 2 or more lines was observed in 1.5% of eyes; however, at a late follow-up visit (average, 18 months), CDVA was within 1 line of the preoperative level in all eyes. Perioperative complications included epithelial abrasions (6%), small tears at the incision (1.8%), and difficult lenticule extraction (1.9%). The cap was perforated in 4 eyes, and a major tear occurred in 1 eye; however, none of these patients had late visual symptoms. In 0.8% (14 eyes), suction was lost during surgery. Re-treatment was successful in 13 eyes, whereas 1 eye had ghost images and was re-treated with topography-guided photorefractive keratectomy (PRK). Postoperative complications included trace haze (8%), epithelial dryness on day 1 (5%), interface inflammation secondary to central abrasion (0.3%), and minor interface infiltrates (0.3%); these complications had an impact on CDVA at 3 months in only 1 case. Irregular corneal topography occurred in 1.0% of eyes, resulting in reduced 3-month CDVA (12 eyes) or ghost images (6 eyes). Topography-guided PRK was performed in 4 eyes, with improvement in 3 cases. Satisfaction was high, with only 2 patients dissatisfied at their latest visit because of blurred vision or residual astigmatism. Overall, SMILE had acceptable safety. Although 1.5% of eyes had reduced CDVA by 3 months, visual acuity was restored in the long term. Likewise, patient satisfaction was high.
Article
To evaluate the visual outcome of refractive lenticule extraction in eyes with myopic astigmatism using the Visumax femtosecond laser. Department of Ophthalmology, HELIOS Klinikum Erfurt, Erfurt, Germany. Nonrandomized clinical trials. The data set encompassed treatments of sphere and astigmatism. Vector analysis was performed to study the astigmatic results at each follow-up visit at 1 week and 1, 3, and 6 months. Visual outcomes were analyzed for the 6-month follow-up period. The data evaluated was a complete set of refractive data of 182 treatments (87 left eyes, 95 right eyes). Efficacy, predictability, and safety with regard to astigmatic correction were comparable to the results with U.S. Food and Drug Administration-approved excimer lasers. At 6 months, the mean error ratio was 0.68 ± 0.75 (SD) and the mean correction ratio was 1.11 ± 0.69. There was slight astigmatic undercorrection (approximately 10%) over time. The residuum of the linear regression analysis of the predictability plot was approximately 0.4 diopter. Ninety-six percent of the eyes had a corrected distance visual acuity (CDVA) of 20/20 or better; no eye had a CDVA worse than 20/32. Femtosecond refractive lenticule extraction is an effective procedure for correcting myopic astigmatism. Drs. Sluyterman v. L. and Russmann are employees of and Drs. Blum and Kunert are investigators for Carl Zeiss Meditec AG, Jena, Germany.
Article
To investigate inter-device agreement between the Pentacam (Optikgerate GmbH, Wetzlar, Germany) and IOLMaster (Carl Zeiss Meditec, Jena, Germany) in measuring corneal power, cylinder, and axis of astigmatism. Retrospective case series reviewing the status of eyes after toric IOL implantation to evaluate inter-device agreement in measuring corneal power, cylinder, and axis of astigmatism. Forty-nine eyes from 41 patients were evaluated. Agreement for corneal power and cylinder were deemed good and moderate, with 95% limits of agreement of -1.02 to +1.13 and -1.37 to +1.09 diopters (D), respectively. Agreement for axis of astigmatism was only fair, with a mean absolute difference of 8.9 degrees (range: 0.3 to 37.7 degrees, standard deviation: 8.79 degrees). Thirty percent of eyes had a 10-degree or greater difference in axis measurements, and 13% of eyes had a 20-degree or greater difference in measurements. Analysis by multivariate logistic regression showed higher cylinder powers associated with discrepant corneal power measurements (odds ratio: 3.46, P = .02), and increasing age was associated with discrepant axis measurements (odds ratio: 1.09, P = .03). Overall, there was no significant difference in accuracy predicting postoperative spherical equivalent refraction. Pentacam and IOLMaster agree well for corneal power but less so for cylinder and axis of astigmatism and thus cannot be used interchangeably.
Article
To present initial clinical experience with small-incision lenticule extraction for the treatment of moderate to high myopia. Department of Ophthalmology, Aarhus University Hospital, Aarhus, Denmark. Prospective clinical study. For small-incision lenticule extraction, an intrastromal lenticule was cut with a femtosecond laser and manually extracted without creation of a flap. Patients were treated and followed for 3 months. Only 1 randomly chosen eye of each patient was used in the statistical analyses. The study enrolled 144 patients. The mean preoperative spherical equivalent was -7.18 diopters (D) ± 1.57 (SD). Of eyes with emmetropia as target refraction, 40% had an uncorrected distance visual acuity of 0.1 logMAR or less 1 day after surgery; this increased to 73% at 3 months. The mean corrected distance visual acuity (CDVA) improved significantly from -0.01 (logMAR) preoperatively to -0.03 3 months postoperatively. None of the 127 eyes lost 2 lines or more of CDVA and 6 eyes lost 1 line of CDVA after 3 months. In contrast, 1 eye gained 2 lines and 24 eyes gained 1 line of CDVA. The achieved refraction was a mean of -0.09 ± 0.45 D from the attempted refraction. Of the eyes, 77% were within ±0.50 D and 95% were within ±1.00 D. Ninety-five percent of the patients would recommend the procedure to others. The refractive predictability, safety, and patient satisfaction 3 months after small-incision lenticule extraction were high and comparable to results in previous studies of femtosecond laser-assisted techniques. Drs. Hjortdal and Asp received travel reimbursement from Carl Zeiss Meditec AG, Jena, Germany. No other author has a financial or proprietary interest in any material or method mentioned.
Article
Purpose: To present our initial clinical experience with ReLEx(®) flex (ReLEx) for moderate to high myopia. We compare efficacy, safety and corneal higher-order aberrations after ReLEx with femtosecond laser in situ keratomileusis (FS-LASIK). Methods: Prospective study of ReLEx compared with a retrospective study of FS-LASIK. ReLEx is a new keratorefractive procedure, where a stromal lenticule is cut by a femtosecond laser and manually extracted. Forty patients were treated with ReLEx on both eyes. A comparable group of 41 FS-LASIK patients were retrospectively identified. Visual acuity, spherical equivalent (SE) and corneal tomography were measured before and 3 months after surgery. Results: Preoperative SE averaged -7.50 ± 1.16 D (ReLEx) and -7.32 ± 1.09 D (FS-LASIK). For all eyes, mean corrected distance visual acuity remained unchanged in both groups. For eyes with emmetropia as target refraction, 41% of ReLEx and 61% of FS-LASIK eyes had an uncorrected distance visual acuity of logMAR ≤ 0.10 at day 1 after surgery, increasing to, respectively, 88% and 69% at 3 months. Mean SE was -0.06 ± 0.35 D 3 months after ReLEx and -0.53 ± 0.60 D after FS-LASIK. The proportion of eyes within ±1.00 D after 3 months was 100% (ReLEx) and 85% (FS-LASIK). For a 6.0-mm pupil, corneal spherical aberrations increased significantly less in ReLEx than FS-LASIK eyes. Conclusions: ReLEx is an all-in-one femtosecond laser refractive procedure, and in this study, results were comparable to FS-LASIK. Refractive predictability and corneal aberrations at 3 months seemed better than or equal to FS-LASIK, whereas visual recovery after ReLEx was slower.
Article
To analyze changes in the eye's refractive properties when a toric intraocular lens (IOL) rotates. Fundación Oftalmológica del Mediterráneo, Valencia, Spain. Experimental study. The matrix definition of astigmatism was used in this theoretical study and compared with another vector representation. Two methods were compared: (1) The cylinder, C, resulting from the addition of 2 cylinders C(1) and C(2) whose axes form an angle a, is obtained by the addition of 2 vectors of values C(1) and C(2) forming an angle 2a; (2) the power matrix, F, of a thin astigmatic dioptric system that decomposes naturally into 3 orthogonal components: the purely spherical part F(nes,) the ortho-astigmatism F(or), and oblique astigmatism F(ob). The residual cylinder was one third of the corneal astigmatism when a toric IOL rotated ±10 degrees when the cylinder values for the cornea (C(1)) and IOL (C(2)) were equal. Nevertheless, in most cases C(1) is greater than C(2); therefore, the residual astigmatism did not change noticeably with small rotations. The angle of rotation, b, which annuls the astigmatism correction, could be obtained from the following: cos(π + 2b) = -r/2, with r being the ratio between the IOL and cornea cylinders. The 2 methods gave equivalent results. When the IOL cylinder had a value different from that of the corneal astigmatism, a better choice would be a lower, rather than higher, cylinder value to reduce residual astigmatism. In general, toric IOL rotations less than 10 degrees changed the eye's refraction less than 0.50 diopter. Thus, small axis rotations are not an obstacle for satisfactory astigmatism correction with toric IOLs. No author has a financial or proprietary interest in any material or method mentioned.
Article
To report the clinical results of small incision lenticule extraction to correct refractive errors using a femtosecond laser to refine the femtosecond lenticule extraction technique. Private laser center, Vadodara, India. Prospective clinical study. The VisuMax femtosecond laser system was used to perform small incision lenticule extraction to treat refractive errors. The laser was used to cut a refractive lenticule intrastromally to correct myopia and myopic astigmatism. The lenticule was then extracted from the stroma through a 3.0 to 5.0 mm incision. Outcome measures were corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), and manifest refraction during 6 months of follow-up. Corneal topography and ocular wavefront aberrations were also measured. The study enrolled 51 eyes of 41 patients. The mean spherical equivalent was -4.87 diopters (D) ± 2.16 (SD) preoperatively and +0.03 ± 0.30 D 6 months postoperatively. Refractive stability was achieved within 1 month (P<.01). Six months after surgery, 79% of all full-correction cases had a UDVA of 20/25 or better. The 6-month postoperative CDVA was the same as or better than the preoperative CDVA in 95% of eyes. Two eyes lost 1 line of CDVA. All-in-one femtosecond refractive correction using a small incision technique was safe, predictable, and effective in treating myopia and myopic astigmatism. No author has a financial or proprietary interest in any material or method mentioned. Additional disclosure is found in the footnotes.
Article
This 6 month prospective multi-centre study evaluated the feasibility of performing myopic femtosecond lenticule extraction (FLEx) through a small incision using the small incision lenticule extraction (SMILE) procedure. Prospective, non-randomised clinical trial. PARTICIPANTS; Ninety-one eyes of 48 patients with myopia with and without astigmatism completed the final 6 month follow-up. The patients' mean age was 35.3 years. Their preoperative mean spherical equivalent (SE) was −4.75±1.56 D. A refractive lenticule of intrastromal corneal tissue was cut utilising a prototype of the Carl Zeiss Meditec AG VisuMax femtosecond laser system. Simultaneously two opposite small ‘pocket’ incisions were created by the laser system. Thereafter, the lenticule was manually dissected with a spatula and removed through one of incisions using modified McPherson forceps. Uncorrected visual acuity (UCVA) and best spectacle corrected visual acuity (BSCVA) after 6 months, objective and manifest refraction as well as slit-lamp examination, side effects and a questionnaire. Six months postoperatively the mean SE was −0.01 D±0.49 D. Most treated eyes (95.6%) were within ±1.0 D, and 80.2% were within ±0.5 D of intended correction. Of the eyes treated, 83.5% had an UCVA of 1.0 (20/20) or better, 53% remained unchanged, 32.3% gained one line, 3.3% gained two lines of BSCVA, 8.8% lost one line and 1.1% lost ≥2 lines of BSCVA. When answering a standardised questionnaire, 93.3% of patients were satisfied with the results obtained and would undergo the procedure again. SMILE is a promising new flapless minimally invasive refractive procedure to correct myopia.
Article
This study evaluates the efficacy, predictability and safety of LASIK surgery as a treatment for myopia performed as part of a large-scale, prospective clinical audit spanning 10 years in an Asian study population and to evaluate the outcomes and trends. Prospective, nonrandomized, single-center, multisurgeon study. We included 37,932 eyes of 19,753 patients that underwent myopic LASIK at the Singapore National Eye Centre between 1998 and 2007. All eyes underwent LASIK as a treatment for myopia. Pre- and postoperative refractions, uncorrected visual acuity (UCVA), and best-corrected visual acuity (BCVA) were documented. Safety, efficacy, refractive predictability, treatment trends, retreatment rates, and complications for mild, moderate, and high myopia according to spherical equivalence (SE) of less than -5.00 diopters (D), -5.00 D or more to less than -10.0 D, and -10.00 D or more, respectively. Patients' median age was 32 years (mean, 33.0+/-7.9 years); there were 6832 males (34.6%) and 12,921 females included. Patients were predominantly ethnic Chinese (90.5%). Mean follow-up time was 68.8 days. The mean spherical error corrected was -5.90+/-2.57 D (median, -5.625 D), and outcomes were categorized into low, moderate, or high myopia. The UCVA achieving > or =20/40 has been consistently above 90% since 2000, with 72.8% achieving > or =20/20. More than 93.0% of eyes achieved within +/-1.00 D target in the last 4 years. An improvement in safety was observed since the start of the study, with the best outcomes observed in 2007; loss of 1 and 2 Snellen line BCVA postoperatively was 2.4% and 0.1%, respectively. The overall retreatment rate was 3.8%; 91% of retreated eyes achieved UCVA of > or =20/30. Between 1998 and 2007, there was a significant improvement in postoperative UCVA and BCVA (P<0.001). Myopic LASIK performed in Asian eyes within a comprehensive LASIK clinical program with appropriate clinical audit governance can be safe and effective, with high refractive predictability. Improvements in the nomograms to prevent undercorrection and to compensate for myopic regression have led to better efficacy after LASIK, with an increasing percentage of patients achieving 20/15 visual acuity postoperatively.
Article
To report the 6-month results of a new method of refractive correction, femtosecond lenticule extraction (FLEx), and the preliminary outcomes in the first 108 eyes. In this prospective study, a flap and a lenticule of intrastromal corneal tissue were cut simultaneously using a femtosecond laser. Thereafter, the lenticule was removed manually and the flap repositioned. One hundred and seven of 108 myopic eyes of 56 patients in the treatment group completed the final 6 months of follow-up. The patients' mean age was 35 years. The preoperative mean spherical equivalent (SE) was -4.59 +/- 1.3 diopters (D). The uncorrected visual acuity and the best spectacle-corrected visual acuity after 6 months, objective and manifest refractions, results of slit-lamp examination, the side effects, and the responses to a questionnaire are reported. Six months postoperatively, the mean SE was -0.19 +/- 0.47 D; 98.1% of treated eyes were within +/-1.0 D, and 74.8% of eyes within +/-0.5 D of the intended correction. Eight (7.4%) of 108 eyes lost one line of Snellen VA, one (0.9%) eye lost two Snellen lines, 46 eyes (43%) gained one line, ten eyes (9.3%) gained two Snellen lines, and the VA remained unchanged in 42 (39.3%) eyes. The patient responses to a standardized questionnaire indicated that 97.1% of patients were satisfied with the obtained results and would undergo the procedure again. FLEx appears to be a safe and promising corneal refractive procedure for correcting myopia.
Article
To determine the magnitude of cyclotorsion during excimer laser ablation using a dynamic iris eye tracker. Guy Hugh Chan Refractive Surgery Centre, Department of Ophthalmology, Hong Kong Sanatorium and Hospital, Hong Kong, China. This retrospective study comprised 245 eyes (137 patients) that had laser in situ keratomileusis (LASIK) for myopia with or without astigmatism by the same surgeon. The magnitude of cyclotorsion during LASIK was recorded as the maximum, average, and minimum positions according to the angle of deviation displayed on the excimer laser computer screen. Measurements of cyclotorsion were performed during laser ablation. The mean total cyclotorsion was 2.181 degrees+/-1.392 (SD) (range 0.0 to 13.3 degrees). The mean average position (AP) was +0.134+/-1.851 degrees (range -7.0 degrees [excyclotorsion] to +12.6 degrees [incyclotorsion]). Forty-five eyes (18.4%) had an AP greater than +/-2 degrees, and 168 eyes (68.6%) deviated from the zero position at the onset of laser ablation. The mean incyclotorsion was 2.136+/-1.440 degrees (78 eyes, 31.8%) and the mean excyclotorsion, 1.772+/-0.809 degrees (78 eyes, 31.8%). Eighty-six eyes (35.1%) had cyclotorsion in both directions (mixed cyclotorsion). The mean cyclotorsion was 2.670+/-1.588 degrees. Eight (3.3%) of the 109 patients having simultaneous bilateral LASIK had bilateral incyclotorsion or bilateral excyclotorsion. Cyclotorsion occurs before and during laser ablation. An active rotational eye tracker is fundamental to compensate for cyclotorsion and to enable greater precision in excimer laser ablation delivery.
Article
To prospectively study the feasibility of femtosecond lenticule extraction (FLE), a new method of refractive correction. Department of Ophthalmology, Philipps University of Marburg and Helios Clinic, Erfurt, Germany. A flap and a lenticule of intrastromal corneal tissue were simultaneously cut with a VisuMax femtosecond laser system. Next, the lenticule was manually removed and the flap repositioned. The target refraction in all cases was -0.75 diopter (D). All 10 myopic eyes in the initial treatment group completed the final 6-month follow-up. The mean patient age was 39 years. The mean spherical equivalent (SE) was -4.73 +/- 1.48 (SD) preoperatively and -0.33 +/- 0.61 D 6 months postoperatively. Ninety percent of eyes were within +/-1.00 D and 40% were within +/-0.50 D of the intended correction. No eye lost 2 or more Snellen lines. Corneal topography showed large, prolate optical zones. Aberrometry showed no significant induction of higher-order aberrations. On a standardized questionnaire, all patients said they were very satisfied with the results. Preliminary results indicate that FLEx [corrected] is a promising new corneal refractive procedure to correct myopia.
Enhancement after small-incision lenticule extraction. incidence, risk factors, and outcomes. Ophthalmology
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Liu YC, Rosman M, Mehta JS. Enhancement after small-incision lenticule extraction. incidence, risk factors, and outcomes. Ophthalmology. 2017;124:813-821.
With-or against-the-rule astigmatism, does it matter in SMILE surgery? Presented at the XXXV Congress of the European Society of Cataract and Refractive Surgery
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Ivarsen A, Hjortdal J. With-or against-the-rule astigmatism, does it matter in SMILE surgery? Presented at the XXXV Congress of the European Society of Cataract and Refractive Surgery; October 7-11, 2017; Lisbon, Portugal.
Outcomes of astigmatism correction in with-the-rule and against-the-rule astigmatism in eyes having small-incision lenticule extraction for myopic astigmatism. Presented at the American Society of Cataract and Refractive Surgery Annual Meeting
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Ganesh S, Brar S, Binesh Tyagi. Outcomes of astigmatism correction in with-the-rule and against-the-rule astigmatism in eyes having small-incision lenticule extraction for myopic astigmatism. Presented at the American Society of Cataract and Refractive Surgery Annual Meeting; April 13-17, 2018; Washington, DC.
Refractive Analysis v.1.0.0: a Matlab tool-box for the analysis of refractive results in anterior segment surgery
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Rodríguez-Vallejo M. Refractive Analysis v.1.0.0: a Matlab toolbox for the analysis of refractive results in anterior segment surgery. 2017. http://test-eye.com/index.php/en/refractive-analysis. Accessed March 24, 2018.