[Enhancements after Refractive Corneal Surgery]. / Refraktive Hornhautchirurgie: Nachkorrekturen.

This review article focusses on the management of enhancements after corneal refractive laser surgery. Fundamental issues regarding enhancement embrace identification of the underlying reason for postoperative ametropia, assurance of stability of refraction, type of primary refractive laser treatment and thorough evaluation of the given anatomical parameters of the cornea. With respect to specific inclusion and exclusion criteria, different surgical options for enhancement strategies are displayed with their particular advantages and disadvantages including preoperative planning of the according laser parameters and postoperative patient management.

[SMILE - Small Incision Lenticule Extraction]. / SMILE ­ Small Incision Lenticule Extraction.

Refractive lenticule extraction is a corneal surgical technique that uses a femtosecond laser exclusively to create an intrastromal refractive lenticule for the correction of myopia and myopic astigmatism. In small incision lenticule extraction (SMILE) the generated refractive lenticule is subsequently extracted through a small incision. The reported efficacy, predictability and safety of the flap-less SMILE procedure is similar to those of femtosecond laser in situ keratomileusis (LASIK). Advantages of SMILE over LASIK include less iatrogenic dry eye, fewer induced higher-order aberrations, and potentially less biomechanical weakening of the cornea. However, there is a steeper surgeon learning curve for SMILE as the procedure is technically more challenging than LASIK. Furthermore, the current SMILE laser platform cannot use cyclotorsion control or eye-tracking technology and retreatment options are more complex compared to LASIK. This review looks at patient selection, surgical method, possible complications, retreatment options, and postoperative outcome of the SMILE technique.

Secondary intraocular lens implantation: a large retrospective analysis.

PURPOSE: To investigate preoperative ocular risk factors and indications for secondary intraocular lens (IOL) implantation and compare postoperative complications, visual and refractive outcomes in a tertiary referral center. METHODS: Patients older than 14 years that underwent secondary IOL implantation and had a minimum follow-up of 3 months were enrolled in this retrospective case series. Preoperative ocular risk factors, indications for surgery, postoperative complications, and visual and refractive outcomes including prediction error (PE) and absolute error (AE) were evaluated. IOLs were fixated in following positions: anterior chamber (AC), retropupillary iris-claw (IC), sulcus, and capsular bag or sclera. RESULTS: One-hundred eighty-two eyes of 174 patients with mean follow-up of 17 ± 13.6 months were evaluated. Leading cause for surgery was IOL dislocation (75%), followed by secondary aphakia (19%) and IOL opacifications (6%). Previous vitrectomy was the major preoperative ocular risk factor (43%). Mean corrected distance visual acuity improved from preoperative 0.68 ± 0.55 to 0.42 ± 0.31LogMAR by the last follow-up (p = 0.001). PE and AE differed highly depending on the indication for surgery (p = 0.041 and p = 0.008, respectively) and the IOL fixation (p = 0.011 and p = 0.028, respectively), with IC-IOLs showing the lowest PE and AE. Postoperative AC-hemorrhage occurred mainly after IC-IOLs (p = 0.003), and postoperative hypotony was significantly higher in eyes with previous uveitis (p = 0.026). CONCLUSIONS: Previous vitrectomy seems to be a major underreported risk factor in eyes that undergo secondary IOL implantation. Refractive outcomes depend on indication for surgery and fixation type, with retropupillary IC-IOLs providing the best refractive results, though not statistically significant compared to other IOL positions.

Long-term database analysis of conventional and accelerated crosslinked keratoconic mid-European eyes.

PURPOSE: To investigate the long-term efficacy of accelerated corneal collagen cross-linking (CXL) in a large mid-European cohort with progressive keratoconus. METHODS: Four hundred thirteen eyes of 316 patients with progressive keratoconus were enrolled and treated with conventional (group A) or accelerated (group B) CXL. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), slit lamp, and Pentacam® examinations were performed before and 12, 24, and 36 months after surgery. Maximum and mean anterior keratometry (Kmax, Kmf), corneal topography indices, and corneal pachymetry (TCT) were examined within each group and between groups. Further subgroup analysis of mild and moderate keratoconic eyes was performed. RESULTS: One hundred thirty-one eyes of 101 patients were treated in group A, 282 eyes of 215 patients in group B. (UDVA, CDVA) and Kmax improved within each group, but not statistically significantly between groups after 36 months (p = 0.081, p = 0.344, p = 0.113, respectively). Kmf remained stable in both groups. TCT decreased significantly in group A (p = 0.014), but remained stable in group B (p = 0.063). Subgroup analysis showed similar results with improvement in visual acuity and keratometry and decrease of TCT. Corneal topography indices showed no differences between the groups after 36 months, but developed differently in the subgroup analysis. No correlation was detected between the change of corneal topography indices and TCT with regard to preoperative Kmax. CONCLUSION: In a large mid-European study population including subgroup analysis of mild and moderate keratoconus, accelerated CXL showed similar results to conventional CXL regarding keratometry, corneal topography indices, and CDVA, but further improvement of UDVA. Preoperative Kmax did not affect the postoperative course of corneal topography indices and TCT.

EGFR inhibitor Gefitinib attenuates posterior capsule opacification in vitro and in the ex vivo human capsular bag model.

PURPOSE: Posterior capsule opacification (PCO) occurs as a common complication after cataract surgery. Gefitinib is a selective inhibitor of the epidermal growth factor receptor (EGFR) which represents a potential pharmacological target for PCO prevention. In this in vitro study, we assessed the effect and biocompatibility of Gefitinib in PCO prophylaxis. METHODS: The effect of Gefitinib on the key pathological features of PCO was assessed in vitro. We determined growth in the human capsular bag model, prepared from sixteen cadaver eyes that underwent sham cataract surgery. Furthermore, two lens epithelial cell lines, HLE-B3 and FHL-124, were used to determine concentration-based effects on cell proliferation. In addition, cell-migration, matrix-contraction, and cell spreading were investigated. To exclude toxic concentrations, Gefitinib was assessed for its biocompatibility on six different human ocular cell types from the anterior and posterior segment of the eye. RESULTS: Gefitinib significantly increased the time until confluence of the capsular bag compared to controls (p < 0.001)). In both human lens epithelial cell lines (HLE-B3 and FHL-124), proliferation decreased significantly and as equally strong after incubation with Gefitinib (p < 0.001), as did chemotactic migration (p = 0.004), matrix contraction (p = 0.001), and cell-spreading (p = 0.001). At the IC50 concentration, Gefitinib was well tolerated by six different human ocular cell types of the anterior and posterior segment. CONCLUSION: The specific EGFR inhibitor Gefitinib might become of clinical relevance in PCO prophylaxis as it attenuated cellular growth and other pathological PCO factors in the ex vivo human capsular bag model and in two human lens epithelial cell lines, while showing good biocompatibility in vitro.

Comparison of intravitreal bevacizumab upload followed by a dexamethasone implant versus dexamethasone implant monotherapy for retinal vein occlusion with macular edema.

PURPOSE: To compare the efficacy and safety of three intravitreal bevacizumab upload injections followed by a dexamethasone implant versus dexamethasone implant monotherapy in eyes with macular edema due to retinal vein occlusion. METHODS: Sixty-four eyes of 64 patients were included in this prospective, consecutive, nonrandomized case series: group 1 consisted of 38 patients (22 with central retinal vein occlusion, CRVO, 16 with branch retinal vein occlusion, BRVO) treated using a dexamethasone implant (Ozurdex) alone; group 2 consisted of 26 patients (14 CRVO, 12 BRVO) treated with three consecutive intravitreal bevacizumab injections at monthly intervals followed by a dexamethasone implant. In case of recurrence, both cohorts received further dexamethasone implants. Preoperatively and monthly best corrected visual acuity (BCVA, ETDRS), central retinal thickness (Spectralis-OCT), intraocular pressure, and wide-angle fundus photodocumentation (Optomap) were performed. The primary clinical endpoint was BCVA at 6 months after initiation of therapy. Secondary endpoints were central retinal thickness and safety of the therapy applied. RESULTS: In group 1, an increase in BCVA of 2.5 (±1.6) letters in the CRVO and of 13.0 (±3.2) letters in BRVO patients was seen after 6 months, in group 2 of 5.9 (±0.4) letters (CRVO) and 3.8 (±2.4) letters (BRVO), which was not statistically significant. When comparing the two treatment groups with respect to the type of vein occlusion, there was a significant advantage for BRVO patients for the dexamethasone implant monotherapy (BRVO patients in group 1, p = 0.005). Central retinal thickness showed a significant reduction after 6 months only in patients of group 1, both for CRVO (p = 0.01) and BRVO (p = 0.003). First recurrence after the first dexamethasone implant injection occurred after 3.8 months (mean) in CRVO and 3.5 months in BRVO patients (group 1), versus 3.2 and 3.7 months, respectively, in group 2. In group 1, 63.6% with CRVO and 50% with BRVO showed an increased intraocular pressure after treatment; in group 2, 57.1% with CRVO and 50.0% with BRVO, respectively. CONCLUSION: In CRVO, there was no difference between the two treatment strategies investigated. However, in BRVO, dexamethasone implant monotherapy was associated with better functional outcome.

OCT- versus Scheimpflug-based Total Corneal Power Measurements Changes in Myopic Astigmatic SMILE Procedures.

PURPOSE: To evaluate the value of total keratometry (TK) to estimate corneal power in eyes that underwent SMILE for treatment of myopia or myopic astigmatism in subgroups of low and high astigmatism. METHODS: The difference between preoperative and postoperative measurements of corneal power (ΔTCRP, ΔTK) was compared with the surgically induced refractive change at the corneal plane (ΔSEco) by Pearson correlation. Vector analysis of TCRP- and TK-derived astigmatism was performed to evaluate the corneal astigmatism. Single-angle plots were generated with the AstigMATIC tool for standard astigmatism vector analysis. RESULTS: Paired t-test revealed statistically significant differences in preoperative (p = .02) and postoperative (p = .0455) measurements between TK and TCRP in the group of high-level astigmatism and the postoperative low astigmatism group (p < .01). No significant differences were found in preoperative data in the group of low-level astigmatism (p = .60). The correlation of ΔSEco and TK (low astigmatism, R2 = 0.978; high astigmatism R2 = 0.980) was stronger than the correlation of TCRP 4.0 mm and ΔSEco (low astigmatism, R2 = 0.743; high astigmatism R2 = 0.959) in both astigmatic groups. The vector analysis demonstrated nearly identical results concerning the correction index (CI) for TK and TCRP. Comparing the difference vector (DV) between both parameters, TK-derived results were closer to the optimum. CONCLUSIONS: The findings endorse TK as a reliable measure of corneal power after SMILE in patients with low and high astigmatism.

Total keratometry for determination of true corneal power after myopic small-incision lenticule extraction.

PURPOSE: To gauge the value of total keratometry (TK) to estimate corneal power change in eyes that underwent small-incision lenticule extraction (SMILE) for treatment of myopia or myopic astigmatism. SETTING: Department of Ophthalmology, Ludwig-Maximilians-University, and SMILE Eyes Clinic Munich Airport, Munich, Germany. DESIGN: Prospective cross-sectional trial. METHODS: A total of 40 eyes of 40 patients who had undergone myopic SMILE were enrolled in this prospective study. Total corneal refractive power (TCRP; Pentacam HR) and TK (IOLMaster 700, Carl Zeiss Meditec AG) values were compared with the clinical history method (CHM). The surgically induced changes in TCRP (ΔTCRP) and TK (ΔTK) were also compared with the changes in spherical equivalent on the corneal plane (ΔSEco). RESULTS: Of the 40 eyes analyzed, the correlation between TK and CHM (R2 = 0.91, P < .001) was stronger than that between TCRP and CHM (R2 = 0.87, P < .001). When compared with the CHM, TCRP underestimated corneal power by a mean relative error of 0.59 diopter (D) and TK by 0.17 D. Linear regression analysis of ΔTCRP/ΔTK and the difference between preoperative and postoperative manifest refraction spherical equivalent at the corneal plane (ΔSEco) showed stronger correlation in ΔTK (R2 = 0.88) than that in ΔTCRP (R2 = 0.82). CONCLUSIONS: The findings endorse TK as an accurate measure for corneal power after myopic SMILE.

Comparison of changes in corneal volume and corneal thickness after myopia correction between LASIK and SMILE.

Myopia is the most common refractive error. Surgical correction with laser is possible. LASIK and SMILE are the techniques currently most used. Aim of the study was to compare changes in corneal volume and thickness after the respective laser treatment. 104 eyes of 52 patients were matched based on refractive error into two equally sized groups, either treated with LASIK or SMILE. Measurements were obtained from the Scheimpflug camera (Pentacam) preoperatively and at 3 and 12 months postoperatively. 3 months postoperatively, the flapless SMILE procedure resulted in a significant overall greater loss of corneal volume (P < 0.01) and corneal thickness (P < 0.01) compared to LASIK. No significant difference was found when comparing the 3 to 12-months values in each group. Within the currently used ranges of refractive error correction, loss in central corneal thickness and corneal volume with SMILE is higher in comparison to LASIK. As greater loss in corneal volume and thickness might contribute to higher level of corneal instability maximum ranges of refractive error correction with SMILE should not supersede those set currently for LASIK until more long-term results on corneal ectasia are available for SMILE.

Comparison of intravitreal bevacizumab versus triamcinolone for the treatment of diffuse diabetic macular edema.

BACKGROUND: Our purpose was to compare the effect of triamcinolone and bevacizumab (Avastin) on the retinal thickness and functional outcome in patients with diabetic macular edema. METHODS AND MATERIALS: A collective of 32 patients, who had been treated by a single 4.0-mg intravitreal triamcinolone injection (group 1), was matched to 32 patients ('matched pairs'), who had received 3 injections of 1.25 mg of bevacizumab within 3 months in 4-week intervals (group 2). The outcome variables were changes in best corrected visual acuity (VA) and central retinal thickness 3 months after therapy. RESULTS: Both groups did not differ regarding preoperative VA and central retinal thickness measured by optical coherence tomography. The baseline mean VA was 0.72 +/- 0.39 logMAR in group 1 and 0.73 +/- 0.39 logMAR in group 2 (p = 0.709). The mean central retinal thickness measured by optical coherence tomography was 548 +/- 185 mum in group 1 and 507 +/- 192 mum in group 2. While the patients in group 1 experienced a slight increase in VA of on average 0.7 lines following a single triamcinolone injection to a mean of 0.64 +/- 0.40 logMAR (p = 0.066) after 3 months, the patients in group 2 showed almost no effect on VA with an average increase of 0.2 lines to a mean VA of 0.72 +/- 0.30 logMAR (p = 0.948) following 3 intravitreal injections of bevacizumab. Comparing the effect on VA between both groups no statistically significant difference (p = 0.115) was noted. Concerning decrease in central retinal thickness both therapies were highly effective (p < 0.001 each), again, without statistically significant difference between the groups (p < 0.128). CONCLUSION: Our data suggest that a single triamcinolone injection may be as effective as a 3 times repeated intravitreal administration of bevacizumab for the treatment of diabetic macular edema. Further prospective trials should be performed.

Surface Ablation Versus CIRCLE for Myopic Enhancement After SMILE: A Matched Comparative Study.

PURPOSE: To compare the outcomes of enhancement after small incision lenticule extraction (SMILE) using surface ablation versus the VisuMax CIRCLE option (Carl Zeiss Meditec AG, Jena, Germany), which converts the SMILE cap into a femtosecond laser-assisted laser in situ keratomileusis flap. METHODS: The databases of the SMILE Eyes centers in Munich, Marburg, and Cologne, Germany, and Linz, Austria, were screened for eyes that had undergone enhancement using surface ablation with mitomycin C or CIRCLE. Eyes from both enhancement methods suitable for a retrospective matched analysis were identified based on pre-SMILE and pre-enhancement mean refractive spherical equivalent (MRSE), astigmatism, age, and corrected and uncorrected distance visual acuity (CDVA/UDVA). Refractive and functional outcomes were compared after a follow-up of 3 months. RESULTS: After the application of the matching criteria on 2,803 SMILE procedures, 24 eyes (12 in each group) with a follow-up of 3 months or longer were available for analysis. Enhancement was performed after a mean 9.7 ± 7.2 (surface ablation) and 11.0 ± 4.4 (CIRCLE) months for a residual MRSE of -0.91 ± 0.55 (surface ablation) and -0.90 ± 0.61 (CIRCLE) diopters. At 3 months, residual MRSE showed comparable accuracy with -0.07 ± 0.19 (surface ablation) and 0.04 ± 0.22 (CIRCLE) diopters (P = .18). UDVA improvement was similar to a final value of 0.02 ± 0.10 (surface ablation) versus 0.03 ± 0.07 (CIRCLE) logMAR (P = .78). Only one eye in the surface ablation group and no eye in the CIRCLE group lost one line of CDVA. At 3 months, the safety (surface ablation: 1.00, CIRCLE: 1.06; P = .36) and efficacy (surface ablation: 0.95, CIRCLE: 1.03; P = .36) indices were equivalent. In terms of speed of visual recovery, at week 1 UDVA and CDVA were significantly better after CIRCLE than surface ablation (P = .008 and .002, respectively). CONCLUSIONS: In this first study directly comparing surface ablation versus CIRCLE enhancement after SMILE, both methods yielded comparable results at 3 months. However, CIRCLE re-treated eyes showed a markedly increased speed of recovery concerning UDVA and CDVA compared to surface ablation. [J Refract Surg. 2019;35(5):294-300.].

The protective effect of quercetin against oxidative stress in the human RPE in vitro.

PURPOSE: To investigate the possible protective effect of the dietary antioxidant quercetin on retinal pigment epithelial (RPE) cell dysfunction and cellular senescence occurring in age-related macular degeneration (AMD). The major flavonoid quercetin was studied on RPE cells in vitro. METHODS: Cultured human RPE cells were incubated with different concentrations of quercetin for 24 hours. Cells were then treated with 150 to 300 microM hydrogen peroxide for 2 hours. Mitochondrial function was measured by using MTT assay and cell vitality by live-dead staining assay. Intracellular levels of glutathione were determined by using a glutathione assay kit. Apoptosis was quantified by a caspase-3 assay, and cellular senescence was quantified by beta-galactosidase staining. Expression of the senescence-associated transmembrane protein caveolin-1 was investigated by Northern and Western blot analyses. RESULTS: Hydrogen peroxide treatment caused significant decreases in mitochondrial function (52%) and in cell vitality (71%), whereas preincubation with 50 microM quercetin diminished this decrease in a dose-dependent manner. Quercetin treatment did not show any notable effect on intracellular levels of glutathione in either used concentration of quercetin. Hydrogen peroxide-induced activation of caspase-3 was reduced by 50 microM quercetin, from 1.9- to 1.4-fold, compared with untreated control (P < 0.001). Hydrogen peroxide caused a large (>90%) dose-dependent increase in beta-galactosidase-positive cells, whereas in the untreated control only single cells expressed this enzyme (<5%). This increase in cellular senescence was significantly attenuated by quercetin in a dose-dependent manner. The highest attenuation was reached at 50 microM quercetin. Quercetin caused a significant dose-dependent reduction of caveolin-1 mRNA 48 hours after treatment with hydrogen peroxide. After 96 hours of incubation, caveolin-1 protein levels were also reduced. CONCLUSIONS: The data demonstrate that quercetin is able to protect RPE cells from oxidative damage and cellular senescence in vitro in a dose-dependent manner. The authors suggest that this increase in antioxidative capacity is--among other mechanisms, such as the intracellular redox state--also mediated by inhibiting the upregulation of caveolin-1. Downregulation of caveolin-1 may be important for the retinal pigment epithelium to prevent apoptotic cell death in response to cellular stress, a condition implicated in the early pathogenesis of AMD. Therefore, the authors believe that the use of antioxidative dietary flavonoids such as quercetin is a promising approach in the prevention of early AMD.

Long-term effect of intravitreal bevacizumab (avastin) in patients with chronic diffuse diabetic macular edema.

PURPOSE: To evaluate the long-term efficacy of bevacizumab for the treatment of chronic diffuse diabetic macular edema after various previous treatments. METHODS: A total of 126 patients (mean age: 66 years) with chronic diffuse diabetic macular edema were consecutively incorporated in this prospective, noncomparative case series. Inclusion was performed independently from the size of edema, retinal thickness, visual acuity (VA), age, metabolic control, type of diabetes, or type of previous treatments. The patients underwent a complete eye examination including best-corrected VA with ETDRS charts, slit lamp examination, intraocular pressure measurement, stereoscopic biomicroscopy of the macula, retinal thickness measurement using optical coherence tomography (OCT), fluorescein angiography, and fundus photography. All patients were treated with repeated intravitreal injections of bevacizumab (1.25 mg). Patients were observed in intervals of 4-12 weeks for a period of up to 6-12 months. RESULTS: All patients had received various previous treatments such as laser treatment (62% focal laser treatment, 38% panretinal laser treatment), vitrectomy (11%), or intravitreal injection of triamcinolone (41%). All patients completed 6 months and 59 patients (47%) completed 12 months of follow-up; within this period 48% had received at least three intravitreal injections of bevacizumab. Mean diameter of foveal avascular zone was 858 +/- 341 microm. At baseline mean VA was 40.3 ETDRS letters (0.82 logMAR Snellen VA) and mean central retinal thickness on OCT was 463 microm. Throughout follow-up VA changes were not significant with a mean change of -1.6 ETDRS letters after 6 months, but significant with +5.1 ETDRS letters after 12 months. Mean central retinal thickness (OCT) decreased to 374 microm after 6 months (P < 0.001) and to 357 microm after 12 months (P < 0.001). Changes of retinal thickness and visual acuity did not correlate. No other factors investigated, such as age, central retinal thickness, or previous treatments, were predictive for a change of VA. Macular ischemia was not exacerbated as a result of the treatment. CONCLUSION: Even in cases with chronic diffuse ischemic diabetic macular edema, a long-term decrease of central retinal thickness can be observed following repeated intravitreal injections of bevacizumab. In these patients, mean decrease in retinal thickness is aligned with a gain in mean VA. Treatment with bevacizumab at an earlier stage of diabetic macular edema without ischemia may be associated with an even better functional outcome.

Influence of total intraocular lens diameter on efficacy and safety for in the bag cataract surgery.

CONTEXT: Intraocular lenses with variable total diameter are supposed to fit better in the capsular bag and lead to fewer complications. AIMS: This study aims to investigate the efficacy and the safety of an intraocular lens model with variable total diameter. SETTINGS AND DESIGN: Prospective randomized intraindividual study. SUBJECTS AND METHODS: Thirty-two eyes of sixteen patients with bilateral age-related cataract received standard cataract surgery with implantation of an intraocular lens with a standard diameter in one eye (Quatrix®, Group A) and with a variable total diameter in the fellow eye (Quatrix Evolutive®, Group B). Primary study endpoints included evaluation of refraction stability and posterior capsule opacification (PCO) over a follow-up period of 6 months. STATISTICAL ANALYSIS USED: SPSS (Version 19.0) was used for statistical analysis. RESULTS: Uncorrected and corrected distant visual acuity after 6 months were 0.24 and 0.1 LogMAR in Group A and 0.23 and 0.09 LogMAR in Group B, respectively. The objective and manifest spherical equivalent (OSE, MSE) 6 months postoperatively were + 0.65 D and + 0.62 D in Group A compared to + 0.33 D and + 0.33 D in Group B respectively (P = 0.665 for OSE, P = 0.208 for MSE). PCO-index increased statistically significant in both groups (P = 0.004 in Group A, P = 0.046 in Group B), but the difference of PCO-index between both groups was not statistically significant (P = 0.569). CONCLUSIONS: An intraocular lens with a variable total diameter shows good visual outcomes and safety performance as well as same outcomes concerning postoperative refractive stability and development of PCO compared to an intraocular lens with standard total diameter.

Corneal Densitometry after Femtosecond Laser-Assisted In Situ Keratomileusis (Fs-LASIK) and Small Incision Lenticule Extraction (SMILE).

PURPOSE: To compare corneal densitometry values after Femtosecond Laser-Assisted In Situ Keratomileusis (Fs-LASIK) and Small Incision Lenticule Extraction (SMILE) using Scheimpflug Imaging. METHODS: Our retrospective clinical trial included a total of 146 eyes where 57 eyes underwent Fs-LASIK and 89 eyes underwent SMILE. Examinations with a Pentacam Scheimpflug device (Oculus, Wetzlar, Germany) were performed before surgery, 1 week, 1 month, 3 months, 6 months, and 1 year after surgery. Detailed data of all four concentric optical zones were acquired - central 0-2 mm, 2-6 mm, 6-10 mm and 10-12 mm. The cornea was divided into anterior 120 µm, middle and posterior 60 µm sections. Values were analyzed during follow-up comparing Fs-LASIK and SMILE. RESULTS: No statistically significant differences in corneal density were detected. The central 0-2 mm anterior area demonstrated a mean 1-year value of 17.99 grayscale units (GSU) ± 0.89 (range 16.60-19.50) after Fs-LASIK versus 17.96 GSU ± 0.98 (range 16.40-20.00) after SMILE. Three months after surgery there was a slight temporary density increase in the 6-10 mm anterior annulus in the LASIK group - 22.19 (SD = 3.99, range: 15.60-30.50) compared to SMILE - 20.39 (SD = 3.79, range 14.70-36.30). CONCLUSION: There were no statistically significant short or long-term differences in postoperative corneal densitometry after LASIK and SMILE, demonstrating SMILE is not inferior in this regard. Known delayed visual acuity recovery after SMILE in relation to LASIK could not be correlated with changes in corneal density.

Impact of a Displaced Corneal Apex in Small Incision Lenticule Extraction.

PURPOSE: To evaluate the possible impact of a displaced corneal apex (point of maximum curvature) on visual results and tomographic parameters after small incision lenticule extraction (SMILE). METHODS: In this retrospective evaluation, eyes with uncomplicated SMILE for myopia correction were classified in two groups based on their preoperative distance between the corneal apex and corneal vertex (corneal intercept with the patient's line of sight) of 1 mm or greater (large A-V distance) or less than 1 mm (small A-V distance). All surgeries were performed during the early learning curve of two surgeons. Visual outcome parameters included uncorrected (UDVA) and corrected (CDVA) distance visual acuity, manifest refractive spherical equivalent (MRSE), and refractive astigmatism 3 months postoperatively. Scheimpflug-derived tomographic outcome parameters included mean keratometry value, root mean square higher order aberrations (RMS HOAs), and optical zone decentration. RESULTS: The study comprised 94 eyes of 48 patients: 44 eyes in the large A-V distance group and 50 eyes in the small A-V distance group. Preoperative and postoperative RMS HOAs were significantly higher in the large A-V distance group than in the small A-V distance group (P = .002 and .008, respectively). Postoperative CDVA was significantly better in the small A-V distance group (P = .014). There were no statistically significant differences in postoperative UDVA, MRSE, refractive astigmatism, mean keratometry value, and optical zone decentration. CONCLUSIONS: After SMILE, CDVA was significantly worse in eyes with a preoperatively displaced corneal apex compared to eyes with a more central corneal apex. However, good visual results were achieved in both groups. [J Refract Surg. 2018;34(7):460-465.].

Wound Healing, Inflammation, and Corneal Ultrastructure After SMILE and Femtosecond Laser-Assisted LASIK: A Human Ex Vivo Study.

PURPOSE: To assess the wound healing, inflammation, and tissue ultrastructure in the human corneal stroma after small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK (FS-LASIK). METHODS: Sixteen corneoscleral discs of 16 human donors unsuitable for corneal transplantation were obtained from an eye bank. Eight eyes underwent SMILE with -5.00 diopters (D) of myopic correction; in 3 of them the lenticule was not extracted. Further 5 donor corneas were subjected to FS-LASIK with -5.00 D ablation, and 3 eyes served as the control group without surgical intervention. Postoperatively, specimens were incubated in organ culture medium for 72 hours before being subjected to immunofluorescence staining for CD11b, Ki67, fibronectin, terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick-end labelling assay, and high-magnification scanning electron microscopy. RESULTS: Keratocyte apoptosis, keratocyte proliferation, and infiltration of immune cells were generally mild and comparable between FS-LASIK and SMILE (irrespective of surgical lenticule extraction). By staining for fibronectin, we observed a trend toward milder fibrotic response in the corneal stroma after SMILE than after FS-LASIK. On the contrary, scanning electron microscopy analysis revealed a smoother, more regular ultrastructural appearance of the residual corneal bed after FS-LASIK. CONCLUSIONS: Corneal stromal wound healing after SMILE and FS-LASIK was virtually identical with respect to keratocyte proliferation and apoptosis in the human donor eye model. Although reactive fibrosis adjacent to the laser application site appeared less marked after SMILE, the stromal bed after LASIK exhibited a smoother surface texture. [J Refract Surg. 2018;34(6):393-399.].

Clinical evaluation of a new correction algorithm for dynamic Scheimpflug analyzer tonometry before and after laser in situ keratomileusis and small-incision lenticule extraction.

PURPOSE: To compare a biomechanically corrected intraocular pressure (bIOP) algorithm provided by the dynamic Scheimpflug analyzer (Corvis ST) with Goldmann applanation tonometry IOP (Goldmann IOP) and standard dynamic Scheimpflug analyzer IOP measurements before and after laser in situ keratomileusis (LASIK) and refractive lenticule extraction small-incision lenticule extraction (SMILE) surgeries. SETTING: Smile Eye Clinic, Munich, Germany, and University of Liverpool, Liverpool, United Kingdom. DESIGN: Retrospective case series. METHODS: Patients scheduled for LASIK and patients scheduled for small-incision lenticule extraction for myopia or myopic astigmatism were included. The preoperative and postoperative evaluations included Goldmann, Scheimpflug tomography, and dynamic Scheimpflug analyzer IOP measurements. RESULTS: The study comprised 14 patients in the LASIK group and 22 patients in the small-incision lenticule extraction group. Preoperative Goldmann IOP and Scheimpflug analyzer IOP values showed significant positive correlation with central corneal thickness (CCT) (P = .05 for LASIK; P = .003 for small-incision lenticule extraction). No significant correlation was found between bIOP and CCT (P > .05). After both surgeries, there were significant decreases in Goldmann IOP (-3.2 mm Hg ± 3.4 [SD] and -3.2 ± 2.1 mm Hg, respectively; both P < .001) and Scheimpflug analyzer IOP (-3.7 ± 2.1 mm Hg and -3.3 ± 2.0 mm Hg, respectively, both P < .001) compared with preoperative readings, whereas bIOP did not differ significantly (0.1 ± 2.1 mm Hg and 0.8 ± 1.8 mm Hg, respectively; P = .80 and P = .273, respectively). CONCLUSIONS: The bIOP readings before and after LASIK and small-incision lenticule extraction were neither significantly different nor correlated with CCT. In contrast, both Goldmann IOP and Scheimpflug analyzer IOP had significant reductions postoperatively and showed significant correlation with CCT preoperatively.

CIRCLE Enhancement After Myopic SMILE.

PURPOSE: To report the outcomes of enhancement after small incision lenticule extraction (SMILE) using the VisuMax CIRCLE option (Carl Zeiss Meditec AG, Jena, Germany), which converts the SMILE cap into a femtosecond LASIK flap for secondary excimer laser application. METHODS: Of 2,065 SMILE procedures, 22 eyes (1.1%) re-treated with CIRCLE with a follow-up of 3 months were included in the analysis. SMILE was performed in the usual manner. For re-treatment, the CIRCLE procedure was performed with pattern D flap creation on the VisuMax system and subsequent excimer laser ablation with a Zeiss MEL 90 laser (Carl Zeiss Meditec) with plano target in all cases. RESULTS: Spherical equivalent was -5.56 ± 2.22 diopters (D) before SMILE and -0.51 ± 1.08 D before CIRCLE. CIRCLE enhancement was performed after a mean of 10.0 ± 7.9 months, allowed for safe flap lifting in all eyes, and resulted in a final manifest refraction spherical equivalent of 0.18 ± 0.31 D at 3 months (P < .008). The number of eyes within 0.50 and 1.00 D from target refraction increased from 31.8% to 90.9% and from 77.3% to 100%, respectively. Mean uncorrected distance visual acuity (UDVA) had already improved from 0.37 ± 0.16 to 0.08 ± 0.16 logMAR at 1 week (P < .0001), resulting in 0.03 ± 0.07 logMAR at 3 months (P < .0001). All eyes gained at least one line of UDVA. Corrected distance visual acuity (CDVA) remained unchanged at all time points (before vs after CIRCLE, P = .40). Two eyes (9.1 %) lost one line of CDVA; no eye lost two or more lines. The safety and efficacy indices were 1.03 and 0.97 at 3 months. CONCLUSIONS: The CIRCLE procedure represents an effective re-treatment option after SMILE. Compared to surface ablation re-treatment after SMILE, CIRCLE seems to offer advantages in respect to speed of visual recovery, safety, and predictability, but at the price of flap creation. [J Refract Surg. 2018;34(5):304-309.].