ReLEx SMILE Research Articles

Reversed Corneal Fibroblasts Therapy Restores Transparency of Mouse Cornea after Injury.

Cell-based therapies using corneal stromal stem cells (CSSC), corneal keratocytes, or a combination of both suppress corneal scarring. The number of quiescent keratocytes in the cornea is small; it is difficult to expand them in vitro in quantities suitable for transplantation. This study examined the therapeutic effect of corneal fibroblasts reversed into keratocytes (rCF) in a mouse model of mechanical corneal injury. The therapeutic effect of rCF was studied in vivo (slit lamp, optical coherence tomography) and ex vivo (transmission electron microscopy and immunofluorescence staining). Injection of rCF into the injured cornea was accompanied by recovery of corneal thickness, improvement of corneal transparency, reduction of type III collagen in the stroma, absence of myofibroblasts, and the improvement in the structural organization of collagen fibers. TEM results showed that 2 months after intrastromal injection of cells, there was a decrease in the fibril density and an increase in the fibril diameter and the average distance between collagen fibrils. The fibrils were well ordered and maintained the short-range order and the number of nearest-neighbor fibrils, although the averaged distance between them increased. Our results demonstrated that the cell therapy of rCF from ReLEx SMILe lenticules promotes the recovery of transparent corneal stroma after injury.

Assessment of Changes in Cap and Residual Stromal Thickness Values during a 6-Month Observation after Refractive Lenticule Extraction Small Incision Lenticule Extraction.

Background: In this study, the changes in corneal cap and residual stromal thickness (RST) values during a 180-day observation period after refractive lenticule extraction small incision lenticule extraction (ReLEx SMILE) were assessed. Methods: Fifty patients underwent ReLEx SMILE using the VisuMax 500 femtosecond laser, with corneal imaging conducted pre and post procedure via anterior segment optical coherence tomography (AS-OCT). Cap thickness in the center and 1.5 mm from the center in four meridians was measured at various intervals. Results: The results showed a significant decrease in cap thickness 180 days post procedure compared to earlier intervals (p < 0.05). Similarly, RST decreased gradually and significantly post procedure (p < 0.05). Notably, changes in cap thickness within the central 1.5 mm area were more dynamic than RST changes during the 6-month observation period following SMILE. Conclusions: The corneal cap thickness measured with swept-source AS-OCT within the central 1.5 mm area underwent more dynamic changes than the residual stromal thickness during the 6-month observation following SMILE.

Visual And Refractive Outcomes of Myopia Astigmatism After Small Incision Lenticule Extraction (ReLEx SMILE) Procedures; Retrospective Study

Abstract&#x0D; Introduction &amp; Objectives : Small Incision Lenticule Extraction (ReLEx SMILE) is becoming more popular as a flapless and minimally invasive form of laser vision correction for the treatment of myopia and myopia astigmatism. This study aimed to assess postoperative visual and refractive outcomes of SMILE- based correction of myopia astigmatism, to evaluate the efficacy, predictability, safety, and stabilityof this procedure over a one-month postoperative period&#x0D; Methods : This retrospective study evaluated 200 eyes of 100 patients who underwent ReLEX SMILE technique, using the Zeiss VisuMax Laser between July 2020 and October 2022. Before surgery, 1 day and 1 month after surgery, the efficacy, predictability, safety, and stability of the procedure were assessed.&#x0D; Results : The preoperative Mean Uncorrected Distance Visual Acuity (UCVA) was 1.55 ± 0.53. Corrected Distance Visual Acuity (BCVA) was 20/20 or better in 74.50% and 90% of eyes in 1 day and 1 month after surgery, respectively. MRSE reduced from -5.22 ± 2.44 to -0.22 ± 0.54 at 1 day post-operative, and -0.19 ± 0.51 at 1 month. 75% of eyes had an unchanged BCVA between 1 day and 1 month after surgery. 72% of eyes achieved spherical equivalent within ±0.5 D and 94% of eyes were within ±1.0 1 month after surgery. The intraoperative complication was suction loss in two patients.&#x0D; Conclusion : SMILE can be considered an effective and safe refractive surgery for the treatment of myopia astigmatism.

Отдаленные результаты ИАГ-лазерной деструкции вросшего эпителия роговицы после Femto-LASIK и ReLEx Smile

Purpose. To evaluate long term cornea characteristics after Nd:YAG laser destruction of epithelial ingrowth in patients after Femto-LASIK and ReLEx Smile and assess its safety according to the state of the corneal endothelium. Material and methods. Due to the rather rare development of this condition, clinical material is presented by 6 cases (6 eyes): 4 men and 2 women aged 22 to 43 years, average 34.6±2.7 years. The average degree of myopia is –4.75 diopters. The Femto-LASIK technique was performed in 3 eyes, and ReLEx Smile – in 3 eyes. All surgeries were carried out without complications, the patients were discharged at the place of residence with the usual recommendations. The timing of epithelial ingrowth after refractive surgery varied from one week to 3 months. The number of sessions of Nd:YAG laser destruction varied regardless of the type of epithelial ingrowth and the technique of previous refractive surgery. The safety of the treatment was confirmed by studying the state of the corneal endothelium of the operated patients. Results. In all 6 cases, it was possible to achieve complete destruction of the zones of epithelial ingrown. Epithelial ingrowth was eliminated at one patient in 5 sessions, at two – in 3 sessions, at two – in 2 sessions and at one – in one session. The number of sessions and the number of impulses in different patients varied greatly and it was not possible to draw a direct parallel between the volume of epithelial ingrown and the total number of impulses. Conclusion. Analysis of long-term results of treatment of epithelial ingrowth by the method of Nd:YAG laser destruction showed good efficiency and atraumaticity for the cornea. The advantage of this technique is its ease of implementation, which is especially important after the ReLEx Smile technology. The use of Nd:YAG laser is effective method of epithelial ingrowth destruction. Key words: Femto-LASIK, ReLEx Smile, epithelial ingrowth, Nd:YAG laser, corneal endothelium, Nd:YAG laser destruction

Оптические методы коррекции посткератопластической аметропии

Purpose. The analysis of the advantages and disadvantages of existing optical methods for correcting postkeratoplastic ametropia (PA). Material and methods. When studying the literature review on PA correction, a search was carried out for sources in the PubMed and Scopus abstract databases for the period up to 2021 inclusive. In total, 50 articles related to the topic of the review were selected, including long-term observations on the methods of optical correction of PA that are currently used worldwide. Results. Today, in addition to spectacle and contact correction, there is a large selection of various methods of surgical correction of PA: wedge resection, various options for keratotomy, implantation of toric intraocular lenses, phakic toric lenses, refractive laser surgery – photorefractive keratectomy, laser in situkeratomileusis, ReLEx SMILE technology, and also implantation of intrastromal corneal segments. The choice of the most optimal optical method for PA correction, depending on the initial individual clinical and functional parameters of the patient, remains quite relevant today. This is due both to a large number of different methods of PA correction, each of which has its own advantages and disadvantages, which necessitates their improvement, and to the need to develop new techniques. Conclusion. Currently, there are a large number of various methods for correcting postkeratoplastic ametropia, each of which has its own advantages and disadvantages. It is necessary to develop a systematic approach to the personalized choice of an optical method for correcting postkeratoplastic ametropia, taking into account its effectiveness and safety, depending on the individual clinical and functional data of the patient. There is a need for the development of new methods of correction that would effectively and safely correct high values of postkeratoplastic ametropia, especially with an asymmetric type of keratotopogram. Key words: postkeratoplastic ametropia, femtosecond laser, corneal segments, scleral contact lenses

Derivation of Human Corneal Keratocytes from ReLEx SMILE Lenticules for Cell Therapy and Tissue Engineering.

Fibroblasts isolated and expanded from ReLEx SMILE lenticules can be a source of human keratocytes. Since corneal keratocytes are quiescent cells, it is difficult to expand them in vitro in suitable numbers for clinical and experimental use. In the present study, this problem was solved by isolating and growing corneal fibroblasts (CFs) with a high proliferative potential and their reversion to keratocytes in a selective serum-free medium. Fibroblasts reversed into keratocytes (rCFs) had a dendritic morphology and ultrastructural signs of activation of protein synthesis and metabolism. The cultivation of CFs in a medium with 10% FCS and their reversion into keratocytes was not accompanied by the induction of myofibroblasts. After reversion, the cells spontaneously formed spheroids and expressed keratocan and lumican markers, but not mesenchymal ones. The rCFs had low proliferative and migratory activity, and their conditioned medium contained a low level of VEGF. CF reversion was not accompanied by a change with the levels of IGF-1, TNF-alpha, SDF-1a, and sICAM-1. In the present study, it has been demonstrated that fibroblasts from ReLEx SMILE lenticules reverse into keratocytes in serum-free KGM, maintaining the morphology and functional properties of primary keratocytes. These keratocytes have a potential for tissue engineering and cell therapy of various corneal pathologies.

Лентикулярная хирургия SMILE после передней послойной кератопластики

Relex Smile technology is an innovative method of laser correction of myopia and myopic astigmatism, minimally affecting the biomechanical properties of the cornea. This technique does not require cutting out a corneal flap and allows to remove the laser-formed corneal lenticule through a small incision. Ametropias, and especially high simple or complex myopic astigmatism, are the most frequent refractive complications after various types of keratoplasty (KP), which significantly reduce the visual acuity and the quality of life in patients, especially when refractive errors cannot be corrected by glasses or contact lenses due to their intolerance or due to anisometropia. Purpose. To evaluate the effectiveness of the residual ametropia correction with SMILE after anterior lamellar keratoplasty (ALK) in a patient with secondary keratectasia. Material and methods. A patient, 30, with complaints of low vision in the left eye. The patient has been noticing a decrease in vision since the age of 18, suffers from myopia. Anamnesis: photorefractive keratectomy and accelerated corneal crosslinking in both eyes. ALK was performed in the left eye. The patient underwent microinvasive femtolaser-assisted extraction of the corneal lenticula using the Relex Smile technique. UCVA and autorefraction data were evaluated 1 week, 1 month and 3 months after surgery. Results. On the first day after the Relex Smile procedure, uncorrected visual acuity (UCVA) was 0.3. 3 months after the operation, UCVA was 0.9 in the left eye. The postoperative spherical equivalent and visual acuity were stable during the 12-month dynamic follow-up, UCVA was 0.9, refractive indices sph –0.5D cyl –0.75D ax 82°, residual corneal thickness 580 microns. Conclusion. Intrastromal extraction of corneal lenticula — Relex Smile -is an alternative, effective, safe and stable technique of induced ametropia correction after deep anterior lamellar keratoplasty. Keywords: Relex Smile, anterior lamellar keratoplasty, induced ametropia, keratectasia

Refractive Outcome After Corneal Lenticule Implantation Ex Vivo Non-Human Study

Purpose To evaluate changes in corneal refractive parameters after implantation of a stromal lenticule of different thickness. We assume that the refractive outcome depends on the optical power of the used lenticule. Methods We conducted an ex-vivo non-human study on 33 normotonic porcine eyeballs divided into two groups, for 4D and 8D human lenticule implantation. Corneal stromal lenticules were obtained as a by-product from a laser procedure ReLEx SMILE. We evaluated corneal refractive parameters measured on Oculus Pentacam© device before and immediately after the intrastromal lenticule implantation. Results There was no statistically significant difference in corneal refractive parameters between the eyeball groups before lenticule implantation. In both groups, the intrastromal implantation in the depth of 300um led to a significant increase of central corneal pachymetry and corneal anterior steepening. In the 4D group the average central corneal pachymetry increased from 903 ± 124.59 to 1230 ± 148.99 (p = 0.0022) and in 8D group from 733.35 ± 69.60 to 1109 ± 161.64 (p = 0.0008). Induced changes in other studied parameters were not statistically significant, Kmax changed from 45.57 ± 2.78 to 72.07 ± 16.83 (p = 0.0094) and Km front from 40.72 ± 1.60 to 48.87 ± 5.83 (p = 0.0037) in 4D group and in the 8D group average Kmax increased from 42.22 ± 1.54 to 62.95 ± 12.67 (p = 0.0001) and K2 front 40.46 ± 1.64 to 51.51 ± 9.63 (p = 0.0037). There were no significant differences in refractive changes between the 4D and 8D groups after lenticule implantation. Conclusion Intrastromal corneal lenticule implantation induces changes in corneal refractive parameters. In both groups, the implantation induced a significant increase of an anterior corneal steepening without any significant influence on posterior corneal flattening. Corneal lenticule implantation did not lead to any significant change of corneal astigmatism. However, in order to have more precise data for future clinical applications we need to continue with the experiments and verify the results on human corneas.

Direct assessment of changes in biomechanical properties of the cornea after ReLEx SMILE and FemtoLASIK surgeries

The SMILE group comprised 23 patients (46 eyes) with spherical refraction -3.8±1.8 diopters (D), the FemtoLASIK group included 18 patients (36 eyes) with spherical refraction -3.5±1.3 D. Analysis of the biomechanical properties of the cornea was carried out using the CORVIS ST device (Oculus, Germany) before and seven days after corneal refractive surgery. In the SMILE group, with intraoperative decrease in corneal thickness of 91.43±19.43 µm, a significant increase in the following parameters was observed: deformation coefficient (DA ratio; p=0.0001), peak distance (PD; p=0.02) and inverse concave radius (ICR; p=0.003); a decrease in the stiffness parameter at first applanation (SP-A1; p=0.0001), Corvis biomechanical index (CBI; p=0.0001), intraocular pressure (IOP; p=0.001). In the FemtoLASIK group, with intraoperative decrease in corneal thickness of 75.33±32.3 µm, we observed a significant increase in DA ratio (p=0.0002), PD (p=0.04), ICR (p=0.0002), a decrease in SP-A1 (p<0.0001), IOP values (p=0.0003). In comparison with the FemtoLASIK group, the deformation amplitude DA changed significantly less in the SMILE group (p=0.04). In the FemtoLASIK group, in comparison with the SMILE group, the DA ratio (p=0.0009) and SP-A1 (p=0.0003) significantly increased. Intraoperative corneal thickness change correlates with ICR both in SMILE (R=0.52) and in FemtoLASIK (R=0.65). Corneal biomechanical properties determined with CORVIS ST in eyes with mild to moderate myopia change to a lesser extent after ReLEx SMILE compared to FemtoLASIK.

Фоторефрактивная кератэктомия как приоритетный метод докоррекции остаточных аметропий

Purpose. To show the effectiveness and safety of the correction of residual ametropia by the PRK method after previously performed keratorefractive operations LASIK, FemtoLASIK, ReLEx SMILE. Material and methods. All patients were divided into 3 groups: Group 1 – previously performed LASIK surgery with insufficient stroma thickness under the valve and patients with unknown parameters of the corneal flap operated in third-party clinics 35 patients (50 eyes), age 46.3 ± 21.9 years, the value of the spherical equivalent – 2.41 ± 1.45. Group 2 – patients after femtolasik 6 patients (6 eyes), age 30 ± 8.3 years, spherical equivalent value – 1.83 ± 0.76. Group 3 – patients after ReLExSMILE 8 patients (11 eyes), age 33 ± 4.4 years, spherical equivalent value – 0.88 ± 0.66. The minimum period after the initial keratorefractive surgery was 1 year, the maximum follow-up period was 4 years. Results. When analyzing the results 6 months after the operation of photorefractive keratectomy: group 1 – the value of the spherical equivalent – 0.26 ± 0.46; group 2 – 0.11 ± 0.2; group 3 – 0.19 ± 0.34. In Group 1, 4 patients (5 eyes) had a loss of lines (3 patients (4 eyes) – 1 line, 1 patient (1 eye) – 2 lines) of maximum visual acuity, all other patients had UDVA to CDVA before the operation of PRK. In groups 2 and 3, the maximum figures of visual acuity were taught. Conclusions. The use of transepithelial photorefractive keratectomy allows to obtain high clinical and functional results, is a safe, easy-to-perform, universal and highly effective method of correcting residual ametropias after various previously performed keratorefractive operations. Keywords: PRK, PRK after LASIK, PRK after FemtoLASIK, PRK after SMILE.

Modern technologies of refractive lenticular extraction in the correction of myopia

Purpose. To analyze the clinical and functional results of refractive lenticular extraction using ReLEx SMILE® and CLEAR® technologies in patients with moderate and high myopia.Materials and methods. 160 patients (160 eyes) aged 18 to 36 years diagnosed with moderate or high myopia, who had binocular vision, average keratometry parameters (43.0–45.0 D), and no contraindications to laser vision correction were operated according to the technology of refractive extraction of lenticula followed up 1 and 3 months after surgery. The patients were divided into 2 groups: (1) SMILE, which included 80 eyes of patients operated with the femtosecond laser VisuMax 500; and (2) CLEAR, including 80 eyes of patients operated using the femtosecond laser FEMTO LDV Z8. Both types of surgery were performed according to standard protocols.Results. No intraoperative complications were recorded. The analysis of clinical and functional parameters in the correction of myopia using the technology of refractive lenticular extraction performed with VisuMax and LDV Z8 femtosecond lasers demonstrated high and comparable efficiency, safety, predictability and stability.Conclusion. Both technologies of refractive lenticular extraction can be recommended for wide clinical use in the correction of moderate and high myopia.

Regarding the Question of Postoperative Asthenopia

Relevance. It is well known that asthenopic complaints, such as increased visual fatigue when working at close range, lacrimation, eye pain and headache after corneal refractive operations in recent years are increasingly common at routine ophthalmological practice. They cause significant subjective discomfort in patients and reduce the satisfaction of the surgery. The pathogenesis of asthenopia is a violation of the coordinated work of the accommodation and binocular systems as a result of their overstrain with excessive visual loads.Purpose. To study the role of the lack of adequate optical correction before surgery in the development of asthenopia in patients with mild and moderate myopia after ReLEx SMILE surgery, as well as to evaluate the effectiveness of drug correction of this condition.Patients and methods. This study included 84 patients (128 eyes) who spend more than 8 hours at a computer due to their professional activity, without pathology of the visual organ that prevents keratorefractive operations, whose average age was 33.2 ± 1.9 years.Results and discussion. The ReLEx SMILE operations in all patients were carried out without complications with the achievement of uncorrected visual acuity equal to the preoperative values of the maximum corrected visual acuity in the period of 1 week and 1 month. In the group with a preoperative lack of adequate optical correction, signs of asthenopia were more often manifested than in patients using full eyeglass or contact correction before surgery. The appointment of the drug Mydrimax® allows to improve the subjective state of patients with asthenopia and leads to the normalization of functional parameters.Conclusion. Corneal refractive operations in patients with the lack of adequate correction of refractive disorders before surgery leads to a significantly significant increase in the initially impaired functional parameters compared to preoperative values, however, it does not reach normal values in most cases and is accompanied by a greater probability of developing postoperative asthenopia.

Morphofunctional Properties of Corneal Stromal Cells.

Human corneal stromal cells were isolated by enzymatic digestion from a new source, lenticules obtained during laser vision correction by the ReLEx SMILe method. The resulting culture was mainly presented by fibroblast-like cells with a phenotype CD90-/CD73+/CD105+/keratocan-/lumican-/ALDH1A1+ that differentiate into keratocytes in a specialized medium. The concentration of fetal calf serum-derived growth factors affects the rate of proliferation, production of erythropoietin and brain neurotrophic factor by corneal fibroblasts, and to a lesser extent, their migration activity and production of extracellular matrix components. Thus, the high functional potential of fibroblast-like cells isolated from stromal lenticles can be used to develop cell technologies in ophthalmology.

Сравнительный анализ частоты развития синдрома сухого глаза после кераторефракционных операций ReLEx SMILE и FemtoLASIK

The main factor in pathogenesis of postoperative dry eye syndrome (DES) is damage to subbasal nerve plexus and stromal nerve endings. Taking into account the different principles of photorefractive effect on cornea of FemtoLASIK and ReLEx SMILE technologies, we decided on our own clinical experience to evaluate incidence of this undesirable complication. Purpose. Comparative study of frequency and timing of relief of postoperative DES after FemtoLASIK and ReLEx SMILE in patients with myopia. Material and methods. The study involved 32 patients (64 eyes) with varying degrees of myopia. The patients were divided into 2 groups: 1st group - 17 patients (34 eyes) after FemtoLASIK surgery, 2nd group - 15 people (30 eyes) after ReLEx SMILE procedure. Control group consist of 15 patients with comparable myopia who had not undergone refractive surgery was also observed. Patients underwent an assessment of the OSDI index, Norn and Schirmer tests, as well as degree of staining of anterior ocular surface 1, 6 and 12 months after refractive surgery. Results. There was statistically significant difference in total tear production, in tear breakup time (TBUT) and in the OSDI index between study groups 1 month after surgery in favor of ReLEx SMILE procedure. After 6 months, TBUT after FemtoLASIK significantly differed from control values. 12 months after surgery, studied parameters did not differ significantly from control. Conclusion. According to our datas, ReLEx SMILE procedure has lower negative effect on ocular surface compared to FemtoLASIK technique, which is manifested by less pronounced subjective symptoms of DES, as well as their faster relief. Key words: dry eye syndrome, ReLEx SMILE, FemtoLASIK.

Visumax Femtosecond Laser Impact on Myopic Residual Refractive Error

Background: Compare the residual refractive power following “small incision lenticule extraction” (SMILE) surgical correction in myopic patients with moderate to severe myopia and myopic astigmatism. Aim: To study the pre op with post op residual refractive status comparison in low to high myopia and myopic astigmatism patients under gone ReLEx SMILE operation. Methods: Prospective comparative analysis with 65 eyes of 33 patients classified into three groups19: mild myopia -1.00 to -3.00 D, moderate myopia -3.25 to -6.00 D, and high myopia -6.25 to -10.00 D, comprising spherical and cylindrical using spherical equivalent (SE). Using the SMILE surgery, each patient were corrected for myopic refractive error. Retinoscope was conducted preoperatively and postoperatively one day and one month following surgery, respectively. Results: Pre op 1 day and 1 month are showing a significant and gradual decrease where low and high myopia are compared, which is statistically significant for both one day (0.007) and one month (0.001) post operatively, but low to moderate (0.282) and moderate to high (0.147) post operatively 1 day and 1 month it is not statistically significant. This indicates that high myopia has greater residual power than low and moderate myopia. Conclusion: This research concludes that residual power increases as myopia increases in severity. As the objective residual power after SMILE surgery is less than +/- 0.50D in approximately 75% - 80% of eyes, SMILE surgery is a suitable alternative for refractive surgery correction with less complications than other refractive surgery techniques.

Do We Have a Place for Non-Steroidal Anti-Inflammatory Drugs in Corneal Refractive Surgery?

Relevance. Corneal refractive surgery is a modern, dynamically developing segment of ophthalmology that provides highly predictable, safe and stable refractive results in patients with a wide range of ametropias. Corneal refractive surgery, usually is chosen by patients who lead an active lifestyle and need rapid medical and social rehabilitation, people with high requirements for the quality of life and showing increased expectations for the result of correction. Perhaps this is due to the fact that, according to a survey at the exit of the Department of refractive laser Surgery of the S.N. Fyodorov Eye Microsurgery Federal State Institution of the Russian Ministry of Health, Moscow, conducted after consulting a surgeon with a description of the course of the operation and the postoperative course, about 1 % of patients refuse surgery, fearing painful sensations in the postoperative period, and 23.4 % of the expected postoperative discomfort causes strong concerns.Purpose. To study the clinical efficacy and safety of Broxinac (0.09 % bromfenac solution) in the early postoperative period of corneal refractive surgery.Materials and methods. The study included 168 patients (168 eyes) with moderate and high myopia after PRK (24 eyes), FemtoLASIK (78 eyes) and ReLEx SMILE (66 eyes), divided into equal subgroups: in the main group, Broxinac was instilled once 30 minutes after the operation, and in the control group — placebo. In the PRK subgroup of the main group, daily instillations of Broxinac were continued until complete reepithelization. The severity of the indicators “eye pain”, “photophobia”, “lacrimation”, “foreign body sensation” was evaluated on a five-point scale, the state of the corneal epithelium when stained with fluorescein, and overall satisfaction with the operation.Results and discussion. It is established that the analgesic effect occurred on average after 4.4 ± 0.6 minutes. Broxinac had a rapid, pronounced analgesic effect in patients in the early postoperative period after keratorefractive surgery, without slowing of corneal reepithelization, and can be recommended for use in clinical practice for analgesia and relief of aseptic inflammatory reaction in the early postoperative period after FemtoLASIK and PRK. The ReLEx SMILE does not require pain relief.Conclusion. Analgesia of the early postoperative period increases patient satisfaction with the result of the operation, popularizes it and helps to attract patients who previously refused surgical correction of ametropia due to fear of painful sensations.

Comparative analysis of protocols for decellularization of corneal lenticular tissue

Shortage of donor corneas is a burning issue in ophthalmology. That is why there is a search for new alternative ways for treating corneal diseases. Decellularization technologies make it possible to create corneal tissue-engineered constructs that can adrress the issue of donor corneal shortage. Objective: to conduct a comparative analysis of effective methods for treating the corneal lenticula and to create an optimized and standardized decellularization protocol. Materials and methods. Corneal stromal lenticules obtained after ReLEx SMILE surgery were chosen for the study. Lenticule parameters: thickness 77–120 microns, diameter 6.5 mm. We used 3 protocols for the treatment of lenticules: 1) treatment with 1.5 M sodium chloride with nucleases (NaCl); 2) 0.1% SDS (SDS); 3) treatment with Trypsin-EDTA solution, followed by double washing in a hypotonic Tris buffer solution with nucleases (Trypsin-EDTA). Optical properties of lenticles were determined spectrophotometrically, where the samples before decellularization served as a control. Fluorescence imaging of nuclear material in the original cryosections was performed using Hoechst dye. The state of collagen fiber ultrastructure was assessed by scanning electron microscopy. The quantitative DNA content in fresh lenticules and in lenticules after treatment was analyzed. Results. All three decellularization protocols effectively removed nuclear and cellular material; the residual DNA content was &lt; 50 ng/mg. However, the Trypsin-EDTA protocol led to significant damage to the extracellular matrix structure, which negatively affected the transparency of corneal tissue-engineered constructs. Transparency of samples for the NaCl protocol was close to native lenticules. Conclusion. To create a corneal tissue-engineered construct, NaCl decellularization protocols appear to be optimized and can be used to treat various corneal diseases.

A to Z of ReLEx SMILE: All you need to know

ReLEx SMILE (Refractive lenticule exchange - Small incision lenticule extraction) is a new generation of laser vision correction, performed using the Visumax femtosecond laser system (Carl Zeiss Meditec AG, Jena, Germany) for the correction of myopia and myopic astigmatism. It ensures greater biomechanical stability, lesser chances of dry eyes and predictable visual and refractive outcomes, making it the procedure of choice for myopic corrections. This article explains in detail regarding the pre-operative work up, steps of the surgical procedure, laser parameters, intra-operative complications such as suction loss, opaque bubble layer, dark spots, cap tear, lenticular adhesion and post-operative complications such as interface haze, interface debris, diffuse lamellar keratitis etc. and their management. The learning curve of SMILE being steeper than that of LASIK, well experienced surgeon and a well co-operative patient would ensure better surgical outcomes, minimising the complications. It also briefly explains about the options available for enhancement post SMILE.

Возможность применения криопротекторов для хранения роговичных тканеинженерных конструкций

Purpose. Conduct a comparative analysis of corneal tissue–engineered constructs that have undergone cryopreservation of three different cryoprotectants. Materials and methods. After refractive surgery Relex SMILE, corneal tissue was obtained which is called a lenticule. Corneal tissue engineering constructs (RTK) have created using decellularization methods that relate to the technologies of tissue and regenerative medicine. For decellularization of the lenticules, a protocol with a 1.5 M solution of Sodium Chloride with DNase 5 U / ml and RNase 5 U / ml was used. After decellularization, RTK was cryopreserved using: 1) 10% DMSO and 90% “corneal storage solution” (Borzenok–Moroz medium), 2) «Cryoderm» cell cryopreservation medium, 3) 100% glycerin. Transparency was assessed using spectrophotometry. The thickness of collagen fibers was assessed by scanning electron microscopy (SEM). Results. When assessing the transparency of the control and experimental groups, a statistically significant decrease in transparency was revealed in the groups using cryoprotectants – Glycerin and Cryoderm (p&lt;0.001), the groups using DMSO did not differ from the control (p=0.99). Also, statistically significant differences were found between the experimental groups «Cryoderm»–DMSO (p=0.02), «Cryoderm»–Glycerin (p&lt;0.001) and Glycerin–DMSO (p&lt;0.001). When evaluating the SEM data, it was found that the thickness of collagen fibers did not differ in the DMSO–Control and Cryoderm–Control groups (p&gt;0.05). The Glycerol–Control group was statistically different (p&lt;0.001). Conclusions. In our work, we have shown the use of DMSO for storing RTK causes thickening of collagen fibers after decellularization of similar to native lenticules. This protocol can be useful for long–term storage and creation of the RTK cryobank. Key words: storage, lenticule, cryoprotectants, cryopreservation, cornea.

Применение лентикулярной ткани в рефракционной хирургии роговицы

Purpose. To identify the problems of using lenticular tissue, its storage, obtaining cell-free scaffolds in corneal tissue engineering, and the possibility of predicting refraction. The unique advantage of Relex Smile technology is that it is a potentially reversible procedure that allows preserve the extracted lenticules and opens up broad possibilities for the use of lenticules in ophthalmic practice in the future. Research in this area demonstrated the potential for implanted autologous and allogeneic lenticules after creating an intracorneal pocket for treating diseases such as presbyopia, corneal perforation, corneal keratectasia, progressive pterygium, progressive keratoconus. In addition, this article presents the results of recent studies describing protocols for cryopreservation and decellularization of lenticules as the most promising methods in tissue engineering in conditions a shortage of donor's cornea. Key words: Relex Smile, lenticule, implantation, cryopreservation, decellularization, tissue engineering.