Laser-assisted Small Incision Lenticule Extraction Research Articles

Fresh Human Myopic Lenticule Intrastromal Implantation for Keratoconus Using SMILE Surgery in a Long-term Follow-up Study: Ultrastructural Analysis by Transmission Electron Microscopy.

To investigate new intrastromal histological structures that develop after myopic human lenticular implantation in keratoconus with femtosecond laser-assisted small incision lenticule extraction (SMILE) surgery using transmission electron microscopy. Sixty eyes with advanced keratoconus indicated for corneal transplantation were included in this study. Fresh myopic lenticular implants were placed in all eyes through SMILE surgery. Lenticular implants were extracted from patients with myopic refractive errors of the cornea, untreated keratoconus, and treated keratoconus following 1, 2, and 3 years of surgery. These five lenticular samples were examined under the electron microscope and compared. Disorganized and thinned collagen fibers were observed in the stroma with degenerative stromal cells (telocyte-like cells and keratocytes) in the keratoconic cornea. Apoptotic bodies and cell debris were easily observed near the disorganized fibers. In contrast, the myopic refractive error of the control and treatment groups demonstrated well-organized parallel lamellar structures. Healthy keratocytes and telocyte-like cells were observed in samples obtained 1, 2, and 3 years after lenticular implantation. Thus, telocyte-like cells may be activated by appropriate stimuli, such as stem cells, and be involved in stromal regeneration. Fresh myopic intrastromal lenticular implantation is a safe, economical, and reliable technique that leads to increased corneal thickness, improved visual acuity, and the regeneration of healthy keratocytes and telocyte-like cells that are involved in stromal regeneration. [J Refract Surg. 2022;38(8):520-528.].

Long-term follow-up of bilateral ectasia after laser-assisted Small-Incision Lenticule Extraction (SMILE) with known risk factors.

To report the long-term follow-up of bilateral ectasia after laser-assisted small-incision lenticule extraction (SMILE) with known risk factors. We report the case of a 23-year-old woman. Preoperative refraction was - 7.25 -2.00 × 20 in the right eye and -7.25 -1.50 × 155 in the left eye. Maximal keratometry was 47.32 diopters and 48.37 diopters, respectively, which was a contraindication to Laser Assisted In Situ Keratomileusis (LASIK) and a SMILE was proposed in 2015. One year after surgery, ectasia developed in the left eye and crosslinking (CXL) was performed. Two years after surgery, ectasia also developed in the right eye and CXL was also performed, leading to stabilization in both eyes five years after surgery. Known contraindications for LASIK are also contraindications for the performance of refractive surgery with SMILE. CXL is an efficient treatment of post-SMILE corneal ectasia.

Novel Corneal Protein Biomarker Candidates Reveal Iron Metabolic Disturbance in High Myopia Eyes.

Myopia is a major public health concern with increasing global prevalence and is the leading cause of vision loss and complications. The potential role of the cornea, a substantial component of refractive power and the protective fortress of the eye, has been underestimated in the development of myopia. Our study acquired corneal stroma tissues from myopic patients undergoing femtosecond laser-assisted small incision lenticule extraction (SMILE) surgery and investigated the differential expression of circulating proteins between subjects with low and high myopia by means of high-throughput proteomic approaches—the quantitative tandem mass tag (TMT) labeling method and parallel reaction monitoring (PRM) validation. Across all corneal stroma tissue samples, a total of 2,455 proteins were identified qualitatively and quantitatively, 103 of which were differentially expressed between those with low and high myopia. The differentially abundant proteins (DAPs) between the groups of stroma samples mostly demonstrated catalytic activity and molecular function regulator and transporter activity and participated in metabolic processes, biological regulation, response to stimulus, and so forth. Pathway enrichment showed that mineral absorption, ferroptosis, and HIF-1 signaling pathways were activated in the human myopic cornea. Furthermore, TMT analysis and PRM validation revealed that the expression of ferritin light chain (FTL, P02792) and ferritin heavy chain (FTH1, P02794) was negatively associated with myopia development, while the expression of serotransferrin (TF, P02787) was positively related to myopia status. Overall, our results indicated that subjects with low and high myopia could have different proteomic profiles or signatures in the cornea. These findings revealed disturbances in iron metabolism and corneal oxidative stress in the more myopic eyes. Iron metabolic proteins could serve as an essential modulator in the pathogenesis of myopia.

Management of remnant intrastromal lenticule of small incision lenticule extraction

Objective To analyze the management and efficacy of remnant intrastromal lenticule during and after femtosecond laser-assisted small incision lenticule extraction(SMILE). Methods The data of 1 715 eyes of 864 cases with SMILE between Apr. 2015 and Mar. 2017 were retrospectively analyzed.All cases were divided into remnant group and normal group based on remnant intrastromal lenticule occured. The cause, clinical characteristics, treatment and efficacy were analyzed. Results The rate of remnant intrastromal lenticule was 0.29%. Lower diopter and difficult lenticule extraction were the main risk factors. The difference of visual acuity and refractive outcoms at 1 month after surgey were not statistically significant between two groups. Corneal topography demonstrated a peripheral area of steepened corneal surface, and front elevation was relatively higher in this area. Abnormal lower curvature was detected in the adjacent area. Conclusion Remnant intrastromal lenticule is a rare complication, good efficacy was achieved with appropriate management. Key words: Femtosecond; Small incision lenticule extraction; Remnant intrastromal lenticule; Corneal topography; Complications

Late-onset diffuse lamellar keratitis 4\xa0years after femtosecond laser-assisted small incision lenticule extraction: a case report

BackgroundTo report a first case of late-onset diffuse lamellar keratitis (DLK) occurring 4 years after femtosecond laser-assisted small incision lenticule extraction (SMILE).Case presentationA 41-year-old man who underwent SMILE 4 years prior developed DLK in the right eye 1 day after he was struck in the eye by a finger while playing with his son. Slim-lamp microscopy and anterior segment optical coherence tomography (AS-OCT) were used to evaluate the cornea of the right eye. Slit-lamp examination of the right eye revealed epithelial exfoliation and stage 3 DLK with diffuse, dot-like, granular haze in the interface between the cap and stromal bed. After intensive treatment with topical corticosteroids, the DLK resolved and corneal transparency was achieved.ConclusionsThis case indicates that DLK can occur several years after SMILE. Ocular trauma may be a risk factor for the development of DLK. The prognosis is usually favorable with early diagnosis and treatment with topical corticosteroids.

Corneal stroma lenticule combined with amniotic membrane transplantation for fungal corneal ulcer

Objective To observe the clinical effect of corneal stroma lenticule combined with amniotic membrane transplantation for fungal corneal ulcer. Methods A retrospective study was performed. The data of 14 eyes of 14 patients with fungal corneal ulcer was collected from January 2015 to December 2015. All patients had histories of plant ocular trauma. Corneal stroma lenticule combined with amniotic membrane transplantation were performed for fungal corneal ulcer. Corneal stroma lenticules were taken from myopia patients who underwent femtosecond laser-assisted small incision lenticule extraction. For all these donors, informed consent was obtained and blood-borne diseases tests were performed. Extracted corneal stroma lenticules were placed into sterilized pure glycerin in a refrigerator at -80 ℃. Results Inflammation of fungal corneal ulcer disappeared and cornea ulcer well healed in all the 14 cases. Thirteen patients underwent 1 operation and 1 patient underwent 2 operations until corneal ulcers healed. Patients with peripheral corneal ulcer had better vision after ulcer healed. Conclusion Corneal stroma lenticule combined with amniotic membrane transplantation for fungal corneal ulcer is safe and effective. Key words: Corneal ulcer; Lenticule, corneal stroma; Transplantation, amniotic membrane

Comparison of ReLEx SMILE and PRK in terms of visual and refractive outcomes for the correction of low myopia

To compare the objective and subjective quality of vision after femtosecond laser-assisted small incision lenticule extraction (SMILE) and photorefractive keratectomy (PRK) for low myopia. One hundred and twenty eyes from 60 patients (34 females, 26 males) undergoing bilateral correction of low myopia (≤-4 D SE) with either ReLEx SMILE or PRK were included. Visual acuity, contrast sensitivity and higher-order aberrations were recorded preoperatively and compared postoperatively. A quality of vision questionnaire was scored and analyzed 3months postoperatively. At 3months, the SMILE group had significantly better uncorrected and corrected distant visual acuity (CDVA), compared to PRK group (p=0.01). Post-op spherical equivalent (SE) was comparable in both groups (SMILE=-0.15±0.19 D, PRK=-0.14±0.23 D, p=0.72). However, SE predictability was better in SMILE group with 97% eyes within±0.05 D compared to 93% eyes in the PRK group. Total higher-order aberrations (HOAs) were significantly higher in PRK compared to the SMILE group (p=0.022). The SMILE group demonstrated slightly better contrast sensitivity, which was significant at spatial frequency of 12cpd (p=0.03). Four eyes in the PRK group had loss of CDVA by one line due to mild haze. Both SMILE and PRK were effective procedures for correction of low myopia. However, SMILE offered superior quality of vision and patient satisfaction due to better postoperative comfort and lower induction of aberrations at 3months.

Corneal Lenticule Allotransplantation After Femtosecond Laser Small Incision Lenticule Extraction in Rabbits.

To investigate the feasibility of allotransplanting extracted lenticules after femtosecond laser-assisted small incision lenticule extraction (SMILE) in rabbits and the subsequent healing process. Fourteen New Zealand white rabbits were divided evenly into 2 groups. The rabbits in group A received SMILE procedures with a -6.00 D correction. The lenticules from group A were immediately inserted into a femtosecond laser-created corneal stromal pocket in group B. After surgery, the anterior segment was assessed in vivo by slit-lamp microscopy, corneal topography, optical coherence tomography, and confocal microscopy. All eyes were enucleated for hematoxylin-eosin staining and transmission electron microscopy after the animals were killed. At postoperative day 1, there was moderate corneal edema in the implanted lenticule stroma. At 6 months, the lenticules were integrated with the surrounding tissue, and the boundary could not be identified through slit-lamp microscopy; regenerated branches of the corneal nerves were thicker than at postoperative month 1 as observed through confocal microscopy. The central corneal thickness increased by 58.75 ± 21.58 μm. The lenticules were gradually integrated with the surrounding tissue, and their density was similar to the adjacent tissue according to optical coherence tomography; however, a clear boundary between the lenticule and surrounding tissue was detectable using light microscopy and transmission electron microscopy, revealing disordered fibers and decreased keratocytes in implanted lenticules. In this model it is feasible and safe to allotransplant extracted corneal lenticules after SMILE. Healing of implanted lenticules after SMILE is stable at postoperative 6 months, but collagen fiber rearrangement requires further investigation.

Suction loss during femtosecond laser–assisted small-incision lenticule extraction: Incidence and analysis of risk factors

To determine the incidence of and analyze risk factors for suction loss during femtosecond laser-assisted small incision lenticule extraction in the management of myopia or myopic astigmatism. Roayah Vision Correction Center, Alexandria, Egypt. Retrospective comparative case-control study. All eyes that had femtosecond laser-assisted small-incision lenticule extraction for the correction of myopia and myopic astigmatism performed between August 2010 and April 2014 were included. Eyes that developed suction loss were identified. Their characteristics, including demographic data (age and sex), eye laterality, manifest refraction, flat keratometry (K) reading, steep K reading, K astigmatism, optical zone, central corneal thickness, and corneal cap diameter and thickness, were compared with those in randomly selected control eyes to determine the risk factors for developing suction loss. Of the 3376 eyes that had femtosecond laser-assisted small-incision lenticule extraction during the study, 70 (2.1%) developed loss of suction. The incidence decreased with surgical experience (5.06% in 2010, 3.59% in 2011, 3.41% in 2012, 2.32% in 2013, and 1.84% in 2014), suggesting a learning curve. A multivariate logistic regression model showed that eyes with a larger cap diameter were significantly more likely to develop suction loss (P = .023; odds ratio, 9.60). Surgical experience significantly decreased the risk for suction loss during femtosecond laser-assisted small incision lenticule extraction for the correction of myopia or myopic astigmatism but did not eliminate it. A larger cap diameter significantly increased the risk for developing the suction loss. No author has a financial or proprietary interest in any material or method mentioned.

Collagen-Based Artificial Corneal Scaffold with Anti-Infective Capability for Prevention of Perioperative Bacterial Infections.

Bacterial infection following implantation of an artificial corneal scaffold is a serious complication. Conventional antibiotic prophylaxis, which includes topical vancomycin application, is limited by low bioavailability, high dosing requirement, and poor patient compliance. The ideal option to overcome these issues is an antibiotic-eluting corneal prosthesis that sustains the local release of drug. In this study, we incorporated vancomycin in thick 15% collagen hydrogels to create an artificial corneal scaffold with anti-infective capability. The incorporation of vancomycin did not significantly alter the Young's modulus, transparency and refractive index of the vancomycin-loaded hydrogel (VH), which were 0.79 ± 0.04 MPa (p = 0.233 compared to blank hydrogel), 94.3 ± 2.3% (p = 0.115) and 1.346 ± 0.005 (p = 0.264), respectively. In vitro, the drug elution was sustained for up to 7 days. The VH was subsequently implanted intrastromally in rabbit corneas, replacing stromal tissue that was removed following femtosecond laser-assisted small incision lenticule extraction procedure. In vivo, the vancomcyin could be detected in the aqueous humor for up to 10 days. We then created a corneal infectious keratitis model by intrastromal injection of 1 × 108 CFU/ml of Staphylococcus aureus inoculate on day 2 postimplantation. On day 3 postinfection, the VH-implanted corneas were clear and nonedematous and showed a substantial reduction of log 2.5 in S. aureus compared to the blank hydrogel-implanted corneas, which appeared hazy, edematous, and had excessive inflammation. Immunohistochemistry of inflammatory marker, CD18, demonstrated a significant reduction in inflammatory cells in VH-implanted corneas (49 ± 9 cells/unit area) compared to blank hydrogel-implanted corneas (523 ± 15 cells/unit area) (p < 0.001). In conclusion, we have demonstrated the efficacy of a drug-eluting corneal implant in preventing perioperative bacterial infections.