Management of traumatic macrostriae in an undisplaced LASIK Flap.

Purpose: To present a case of traumatic late macrostriae of Laser in situ keratomileusis (LASIK) flap managed by flap lifting, stretching, and polishing. Material and method: A patient presented with a history of defective vision in his right eye following trauma with a rubber ball 10 days ago. He had undergone an uneventful LASIK surgery 4 years ago. Ocular examination showed visual acuity of 20/200, multiple parallel radiating folds in an undisplaced LASIK flap in the inferonasal quadrant, and sphincter tear. This case required an urgent surgical intervention. Epithelial debridement, flap lifting, gentle stretching, and irrigation were performed to smooth out the striae. A bandage contact lens was applied to ensure proper wound apposition. Results: The postoperative period was without complications, and the patient achieved a final visual acuity of 20/20. Discussions: The insufficient wound healing of the LASIK flap results in a cornea with compromised biomechanical strength. They remain susceptible to trauma for a long duration after surgery. Traumatic injury to these eyes can lead to late macrostriae formation, which results in visual deterioration. Cases of macrostriae presenting late require surgical debridement of epithelium, which keeps these folds fixed. It should be followed by flap irrigation and stretching to smooth these striae. Conclusions: Since LASIK wound healing is always incomplete, it is crucial to inform patients about the potential risk of trauma. Any traumatic flap injury requires thorough examination and proper management of these cases results in excellent visual gain.

Corneal stromal lenticule transplantation for the treatment of congenital optic disc pit maculopathy : a case report and review.

BACKGROUND: Congenital optic disc pit (ODP) is a relatively uncommon congenital anomaly of the optic disc, which seriously affects the patient's vision when combined with optic disc pit maculopathy(ODP-M). Currently, the treatment of ODP-M remains a clinical challenge and a focus of research. CASE PRESENTATION: A boy had a pit in the inferotemporal segment of the optic disc with ODP-M. Optical Coherence Tomography(OCT) showed ODP and serous retinal detachment. He was treated with pars plana vitrectomy(PPV), followed by Corneal Stromal Lenticule (CSL) sealing and C3F8 tamponade. In the end, significant anatomical improvement was achieved, and the Best Corrected Visual Acuity(BCVA) was improved. CONCLUSIONS: The CSL transplantation may be a viable therapeutic option for improving ODP-M with stable anatomical and functional result. However, more cases and longer follow-up are needed to confirm the safety and effectiveness of the technology.

Corneal Epithelial Remodeling Following Cylinder Correction With SMILE or FS-LASIK: A Contralateral Comparative Study.

PURPOSE: To compare the corneal epithelial remodeling in eyes with high astigmatism that had small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). METHODS: Seventy-four patients with myopic astigmatism of greater than -2.00 diopters (D) and little binocular difference in spherical equivalent were included in this contralateral comparative study. All patients received SMILE in one eye and FS-LASIK in the other eye randomly. The corneal epithelial remodeling pattern was mapped using the latest RTVue spectral-domain optical coherence tomographer (Optovue) by region. RESULTS: Satisfactory refractive correction was achieved in all enrolled eyes with either SMILE or FS-LASIK. The corneal epithelium gradually thickened following surgical cylinder correction, distributing mainly along the flat medium. The corneal epithelium proliferation is milder centrally but more pronounced in the mid-peripheral area after SMILE, compared with FS-LASIK. The flat-steep difference in corneal epithelial thickness (CET) is evident in the mid-peripheral and peripheral areas, which is more obvious in SMILE. Residual cylinder was positively correlated with CET in eyes that had FS-LASIK, but not SMILE. More importantly, these epithelial changes were positively correlated with the ablation depth and higher order aberrations following surgical refractive correction. CONCLUSIONS: The postoperative CET map varied between SMILE and FS-LASIK. In eyes with high astigmatism, SMILE surgery is followed by milder and more stable corneal epithelial thickening. Moreover, the corneal epithelium is sensitive to stromal ablation and corneal remodeling is crucial to the postoperative visual quality. This study rigorously distinguished the CET difference between SMILE and FS-LASIK in astigmatic eyes and shed light on subsequent research. [J Refract Surg. 2024;40(10);e728-e741.].

Refractive Coupling Effects in Keratorefractive Lenticule Extraction Procedures: A Machine Learning-Assisted Approach.

PURPOSE: To evaluate the impact of refractive couplings in myopia and myopic astigmatism with two different keratorefractive lenticule extraction (KLEx) systems. METHODS: This was a retrospective evaluation of refractive outcomes with two different lasers studying 2,841 eyes undergoing small incision lenticule extraction (SMILE) (VisuMax 500; Carl Zeiss Meditec) and 2,528 eyes undergoing SmartSight (ATOS; SCHWIND eye-tech-solutions GmbH). Coupling effects (derived from the ratio between partial slopes) were determined for sphere and cylinder and for spherical equivalent, cardinal, and oblique astigmatism separately. RESULTS: Statistically significant coupling effects were observed for both the VisuMax and ATOS systems, as indicated by P values less than .05. For the VisuMax, a coupling effect of 8% of cylinder into sphere and a 2% coupling of sphere into cylinder was found. For the ATOS, the coupling effect of sphere into cylinder was 1%. A 3% coupling effect of oblique astigmatism into cardinal astigmatism in the VisuMax, and conversely, a 0.1% coupling effect of defocus into oblique astigmatism in the ATOS were found. In cases with no astigmatism plan, sphere had a 2% effect on induced astigmatism in the VisuMax and 0.6% in the ATOS. In high astigmatism plans, sphere had a significant 16% impact on cylinder in the VisuMax. Additionally, the effect of defocus on cardinal astigmatism was 6% in the VisuMax and 0.8% on oblique astigmatism in the ATOS. CONCLUSIONS: Despite the P values less than .05 indicating statistical significance, the observed coupling effects were consistently low, with magnitudes below 10%, even for astigmatism exceeding 2.50 diopters. These couplings may be partly attributed to cross-effects of torsional eye movements. Coupling values for KLEx were markedly lower than those reported for non-aspheric excimer laser ablations. The results suggest that surgical results may be refined further by optimizing nomograms to mitigate coupling effects. [J Refract Surg. 2024;40(10):e706-e715.].

Comprehensive assessment of corneal microstructural changes following V4c implantable collamer lens surgery using in vivo confocal microscopy.

BACKGROUND: Implantable Collamer Lense (ICL) presents a viable alternative to conventional refractive surgeries, but their impact on corneal microstructure remains unclear. By employing in vivo confocal microscopy (IVCM), we examined changes in stromal and endothelial cells following the insertion of V4c ICLs, with the goal of enhancing post-surgical care and outcomes. METHODS: In this longitudinal investigation, we conducted detailed preoperative assessments on 103 eyes from 53 participants. Follow-up evaluations were carried out after surgery at set intervals: one day, one week, one month, three months, six months, and twelve months. We used IVCM to analyze changes in stromal and endothelial cells. To assess differences between pre- and post-surgery variables and to investigate correlations with age, axial length (AL), and spherical equivalent refraction (SER), we applied a repeated measures mixed-effects model, with statistical significance set at P < 0.05. RESULTS: No vision-threatening complications were reported post-surgery. Significant reductions in stromal cell density (SCD) were observed postoperatively, with anterior and mid- SCD reaching their lowest values at 3 months and posterior SCD at 1 month, remaining below baseline at 12 months. endothelial cell density (ECD) and percentage of hexagonal cells (PHC) decreased initially, recovering by 12 months. Conversely, endothelial cellular area (ECA) and coefficient of variation of cell size (CoV) increased postoperatively, with the most significant change at 1 week. Endothelial deposits were detected in 49 of 101 eyes on postoperative day 1, half of them were absorbed within 3 months post-surgery. Changes in posterior SCD were negatively related to AL, while AL, SER, lens thickness showed associated with endothelium changes. CONCLUSION: Our findings elucidate the corneal microstructural changes following V4c ICL implantation, particularly the significant early reductions in stromal and endothelial cell densities. We recommend careful management of viscoelastics during surgery to minimize endothelial deposits that may harm the endothelium. Enhanced early postoperative monitoring and these surgical adjustments can lead to improved surgical and post-surgical care, ultimately supporting better patient recovery.

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

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

Analysis of corneal remodeling post-myopic photorefractive keratectomy with the WaveLight® EX500 excimer laser.

Refractive error is becoming a significant public health issue. Photorefractive Keratectomy (PRK) is a corneal surface surgical technique that removes the corneal epithelium before stromal photoablation by ultraviolet radiation from the Excimer laser. We designed a retrospective study to characterize corneal remodeling after myopic Photorefractive Keratectomy and assess the accuracy of laser-predicted ablation depth (AD). This study took place in 15-20 National Ophthalmology Hospital, Paris, France. 150 eyes with preoperative manifest spherical equivalent between - 10.00D and - 0.25D and cylinder < 3D, treated with the WaveLight® EX500 laser between 01/2019 and 01/2023, were followed for at least three months. The main outcome measurements were postoperative changes in epithelial (ET) and stromal (ST) thicknesses measured with spectral domain optical coherence tomography and mean simulated keratometry (SimK) assessed with corneal topography. The central ET significantly decreased at M1, increased over the preoperative value from M1 to M6, and stabilized after M6. The increase in central ET after M1 was associated with an increase in mean SimK (r = 0.34). The achieved AD was 7.9 ± 8.0 µm greater than the laser-predicted AD. Stromal over-ablation was significantly and independently associated with myopia > 6D preoperative mean SimK > 44D and transepithelial procedures.

Study of corneal and retinal thicknesses at five years after FS-LASIK and SMILE for myopia.

BACKGROUND: This study aimed to observe corneal and retinal thicknesses at 5 years after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE) for myopia, investigate the effect of epithelial remodeling on refractive status and visual quality, and compare retinal thicknesses among fundus tessellation grades. METHODS: Patients who received FS-LASIK or SMILE 5 years before were enrolled in this cross-sectional study. After 1:1 propensity score matching, each surgical group obtained 177 patients (177 eyes). Examinations including visual acuity, refraction, corneal and retinal thicknesses, corneal higher-order aberrations (HOAs), and fundus photography were performed in this visit at 5 years after surgery. The Quality of Vision (QoV) questionnaire was used to assess visual symptoms and overall satisfaction. Corneal and retinal thicknesses between groups were compared, contributing factors were analyzed, and correlations with postoperative refractive status, HOAs, QoV scores and overall satisfaction were evaluated. RESULTS: The discrepancy of epithelial thickness between central and pericentral zones in FS-LASIK group was larger than that in SMILE group, which was negatively correlated with postoperative spherical equivalent (SE), positively correlated with spherical aberration (all P < 0.05), but not correlated with QoV scores and overall satisfaction (all P > 0.05) in both surgical groups. There was no statistical difference in stromal thickness and total corneal thickness (all P > 0.05). Most annuluses of epithelial and stromal thicknesse were linearly related to preoperative SE (all P < 0.05). The macular thickness, ganglion cell complex thickness, and retinal nerve fiber layer thickness exhibited comparable values between two surgical groups and four fundus tessellation grades, with no significant association observed with postoperative SE (all P > 0.05). CONCLUSION: The tendency that epithelial thickness in central zone was thicker than peripheral zone was more obvious at 5 years after FS-LASIK compared to SMILE. This uneven distribution of epithelial thickness might play a role in myopic regression and the changes in HOAs, especially in patients with high myopia, but it had little effect on patients' subjective visual quality and satisfaction. Retinal thicknesses were not affected by these two surgical methods, and they did not appear to be the clinical indicators for myopic regression or fundus tessellation progression.

Microsporidial stromal keratitis: treatment outcomes, clinical manifestations, confocal microscopy and histopathology findings: a retrospective observational study.

OBJECTIVE: Microsporidial stromal keratitis (MSK) is an uncommon disease. Only several case series have been reported. We aimed to describe the clinical manifestations, histopathology and treatment outcomes of MSK. METHODS AND ANALYSIS: Retrospective data of MSK diagnosed between January 2009 and December 2020 at the King Chulalongkorn Memorial Hospital, Bangkok, Thailand were retrieved. The diagnosis was made based on corneal scraping, corneal biopsy and corneal button histopathology findings. Detailed clinical characteristics, histopathological findings and treatment outcomes were reviewed and analysed. RESULTS: 21 patients with MSK with a mean age of 63.8 years (SD 12.2) had an indolent disease onset with a median of 9 months (IQR 2.2-12.0). Five patients (23.8%) experienced ocular traumas. Herpes stromal keratitis was the most common preliminary diagnosis (33.3%), followed by non-specific ulcers and fungal keratitis. The most common corneal finding was multifocal grey-white lesions with anterior to mid-stromal infiltration and fluffy borders (66.7%). Pathogens were identified by modified trichrome staining of corneal scrapings in 11 of 14 cases (78.6%). Histopathological examination showed positive Ziehl-Neelsen staining in 17 of 19 cases (89.5%). All patients received surgical treatment, with 18 receiving therapeutic penetrating keratoplasty (TPK), 2 undergoing deep anterior lamellar keratoplasty and 1 undergoing femtosecond laser-assisted anterior lamellar keratoplasty. The overall cure rate was 76.2% after the first surgery and 95.2% after the second surgery. CONCLUSION: MSK can be easily underdiagnosed. Clues to diagnosis included a history of chronic refractory stromal infiltration and typical corneal findings of deep stromal infiltration, without epithelial defects. TPK is the preferred treatment for MSK.

Comparing the Postoperative Outcomes of Intrastromal Corneal Ring Segments in Three Different Topographic Patterns of Eccentric Keratoconus.

PURPOSE: To compare the postoperative outcomes following implantation of KERATACx ring segments (Imperial Medical Technologies Europe GmbH) in patients having eccentric keratoconus with three different topographic patterns. METHODS: This retrospective cohort study was conducted at Maadi Eye Subspeciality Center, Cairo, Egypt. The study included patients with keratoconus who had implantation of KERATACx ring segments. Three groups were segregated based on topographic keratoconus patterns using the Sirius CSO Topographer (CSO Italia): type I ectasia where the cone coincides with the corneal flat axis, type II ectasia in which the cone coincides with neither the steep nor the flat axis and lies between the two axes, and type II ectasia for cones coinciding with the corneal steep axis. The visual and topographic outcomes were compared preoperatively and postoperatively for the three enrolled groups. RESULTS: This study enrolled 92 eyes of 92 patients and had a mean ± standard deviation follow-up of 16.9 ± 9.2 months. The patients' medical records revealed that night vision complaints and halos around the light were experienced the most by the type III ectasia group (31.25%). For the type III ectasia group, four topographic indices and one visual parameter did not show statistically significant differences between the preoperative and postoperative data (inferior-superior difference at 2- and 4-mm diameter, coma aberration, higher order aberrations, and uncorrected distance visual acuity), contrary to the type I and II ectasia groups, which showed significant improvements in all evaluated parameters. CONCLUSIONS: The type III morphological pattern of ectasia is the least likely to benefit from KERATACx ring segments implantation. [J Refract Surg. 2024;40(9):e625-e634.].

Low Contrast Acuity Outcomes After SMILE and LASIK.

PURPOSE: To compare early visual quality of small incision lenticule extraction (SMILE) versus laser in situ keratomileusis (LASIK) in terms of low contrast acuity. METHODS: A secondary analysis was performed using a harmonized dataset derived from two completed prospective cohort studies on active-duty military service members undergoing either SMILE (n = 37), wavefront-guided (WFG) LASIK (n = 51), or wavefront-optimized (WFO) LASIK (n = 56). Night vision and photopic and mesopic low contrast visual acuity (LCVA) up to 3 months postoperatively were compared between groups. RESULTS: Compared to SMILE-treated eyes, WFG LASIK-treated eyes had significantly better night vision and photopic LCVA at 1 month postoperatively (beta = -0.039, P = .016; beta = -0.043, P = .007, respectively). WFO LASIK-treated eyes had significantly better photopic LCVA at 1 month postoperatively (beta = -0.039, P = .012) but had worse mesopic LCVA at 3 months postoperatively (beta = 0.033, P = .015) versus SMILE-treated eyes. CONCLUSIONS: SMILE and LASIK, on either a WFG or WFO laser platform, yielded excellent outcomes, but LCVA seemed to recover quicker following LASIK compared to SMILE. [J Refract Surg. 2024;40(9):e667-e671.].

Implantation of asymmetrical corneal intrastromal rings: A case series.

This case series reports eight eyes with keratoconus treated with laser implantation of one or two segments of progressive thickness corneal intrastromal ring (PT-ICRS). In this case series, it was evident that the insertion of PT-ICRS induces more pronounced corneal flattening at the thickest point, causing a reduction in distortion (coma) and lower astigmatism, resulting in a remarkable improvement in vision. Compared to the implementation of traditional intrastromal rings, the PT-ICRS variant showed superior results despite the small sample size. However, the same degree of asymmetry enhancement was not observed in cases in which a 330° PT-ICRS was implanted, despite the improvement in visual results when replacing a 320° traditional ring with a 330° PT-ICRS. These conclusions are limited as this is a case series with few cases.

Correction of High Astigmatism by Autologous Astigmatic Lenticule Reshaping and Rotation.

PURPOSE: To explore the use of autologous astigmatic lenticule reshaping and rotation surgery to correct high astigmatism in conjunction with excimer laser technology to correct residual refractive error. METHODS: Six patients with high astigmatism (8 eyes, all with astigmatism from -5.50 to -11.00 diopters [D]) seeking refractive error correction were enrolled. The following methods were used to correct refractive errors that could not be corrected by a single conventional surgery: (1) cutting of a customized lens using FLEx technology, (2) lifting of the corneal flap and reshaping the autologous astigmatic lenticule in situ using an excimer laser, and (3) rotation of the autologous astigmatic lenticule by 90°. Uncorrected distance visual acuity, subjective refraction, corneal topography, and anterior segment optical coherence tomography were performed preoperatively and postoperatively. RESULTS: The efficacy and safety indices at 6 months postoperatively were 0.93 ± 0.18 and 1.06 ± 0.11, respectively, the spherical equivalent remained stable and close to emmetropia (-0.13 ± 0.70 D) from 1 to 6 months postoperatively, postoperative astigmatism was generally mildly undercorrected (-1.22 ± 0.43 D), and the difference in corneal curvatures at 2 mm from the apex of the cornea was significantly reduced compared to preoperatively (P < .05); however, the corresponding values at 1 and 3 mm showed no difference. CONCLUSIONS: Correction of high astigmatism with autologous astigmatic lenticule reshaping and rotation surgery is tissue-sparing, predictable, and significantly improves postoperative visual acuity and quality. This method is feasible and safe, with predictability requiring further study. This novel surgical approach has potential for patients with high astigmatism that cannot be corrected by conventional refractive surgery. [J Refract Surg. 2024;40(8):e554-e561.].

Ex Vivo Lenticule Customization for Stromal Lenticule Addition Keratoplasty.

Purpose: The purpose of this study was to explore the optimal shape of customized lenticules for stromal lenticule addition keratoplasty (SLAK) for off-centered ectasia. Methods: Two different methods to create ex vivo models of eccentric-keratoconus were investigated. Twelve human corneas were used to create model 1 by a hyperopic photorefractive keratectomy (PRK), and model 2 by masked phototherapeutic keratectomy (PTK) on the anterior corneal surface, whereas both types received myopic ablation of the posterior surface. Keratoconus models underwent a modified femtosecond laser (FSL) flap-cut to create stromal pockets. Sixteen human corneas underwent FSL dissection to obtain four lenticule types: type I (planar) and type II (negative) lenticules were used without modifications, whereas type III (customized-planar), and type IV (customized-negative) lenticules underwent further masked-PRK to obtain an asymmetric bow-tie shape. Topographic, aberrometric analysis, and anterior segment optical coherence tomography (AS-OCT) were performed in all recipient corneas before and after lenticule implantation. Results: Keratoconus model was successfully reproduced. Tomographic analysis showed a significant inferiorly decentered corneal steepening with coherent stromal thinning. Model 2 reproduced better the curvature of real keratoconus. Lenticules type I implantation induced a homogeneous corneal thickening, type III produced higher thickening in the inferior half of the cornea. Type II determined a maximal peripheral pachymetric increase, with a gradual reduction toward the center, and type IV presented an asymmetric peripheral thickening. Topographic assessment showed a cone apex flattening in all cases, but it was significantly higher in types II and IV. Customized lenticules improved significantly corneal surface regularity regarding types I and II. Conclusions: The approach of customizing lenticules by increasing their asymmetry and tailoring the re-shaping effects, may improve SLAK outcomes in eccentric keratoconus.

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

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

Comparison between 80-microns versus 100-microns flap femtosecond LASIK for correction of myopia and myopic astigmatism.

PURPOSE: This study aimed to compare the safety, efficacy, and visual outcomes of 80-microns LASIK versus 100-microns LASIK in managing myopia and myopic astigmatism. The study was conducted at a tertiary care hospital in North India. METHODS: This was a prospective contralateral eye study that included patients with myopia and myopic astigmatism seeking refractive correction. The eligibility criteria included normal corneal topography, an epithelial thickness less than 60 microns, a calculated percentage tissue ablation (with 100-microns flap) less than 40%, a calculated residual stromal bed thickness (with 100-microns flap) more than 300 microns, and willingness to participate and follow up. Patients with glaucoma, cataracts, other visually disabling ocular pathologies, and a history of past ocular surgery were excluded. All patients underwent LASIK with 80-microns LASIK in one eye and 100-microns LASIK in the other eye. The patients were followed up for 6 months, and the results were analyzed. RESULTS: The study included 216 eyes of 108 patients. The mean preoperative spherical equivalent in the 80-microns group and the 100-microns group was -3.53 ± 1.81 and -3.69 ± 1.32 diopters, respectively (P = 0.78). The mean 6 months decimal postoperative UCVA was 0.98 ± 0.13 in the 80-microns group and 0.97 ± 0.14 in the 100-microns group (P = 0.99). The postoperative change in the higher-order aberration profile was comparable in both groups (P = 0.78). The percentage tissue ablation was significantly lower in the 80-microns group (P = 0.002). The incidence of flap micro striae and OBL was higher in the 80-microns group, while neither of these had any visual implications. CONCLUSION: The study concluded that 80-microns LASIK is an efficacious and safe alternative to 100-micron LASIK, especially useful in patients with higher myopia.

A Technique of Multiple Corneal Allogeneic Ring Segments Prepared From a Single Corneal Graft: A Case Series.

PURPOSE: To describe a novel technique for preparing multiple corneal allogeneic ring segments (CAIRS) from a single corneal graft using femtosecond laser technology. METHODS: This is a case series of 10 eyes from 10 patients with keratoconus who underwent FS-assisted CAIRS implantation using corneas from 4 donors at the Hospital Foundation Adolphe de Rothschild-Noémie de Rothschild institute. A preoperative and postoperative examination was performed at 1 day, 1 week, and 1 month. Anterior segment OCT and corneal tomography with aberrometric and pachymetric analyses were performed at each visit. Visual, refractive, and topographic parameters were extracted. The thickness and width of implanted CAIRS were analyzed. RESULTS: Patients were classified according to keratoconus severity: group A (maximal keratometry Kmax <75D) and group B (Kmax >75D). At 1 month postoperatively, both groups A and B showed a significant decrease in mean keratometry by 4.78 ± 1.57D and 12.87 ± 4.62D, respectively. Total and higher order aberrations decreased by 5.66 ± 4.55 and 0.65 ± 1.54 in group A and by 9.45 ± 9.15 and 0.49 ± 1.39 in group B, respectively. The corrected distance visual acuity improved by 4.8 ± 1.7 lines in group A. Visual improvement was not significant in group B. One eye in group B exhibited acute rejection and required explantation. CONCLUSIONS: FS-assisted multiple CAIRS implantation using a single corneal graft maximizes the utilization of viable corneal tissue. CAIRS implantation is an effective and biocompatible therapeutic alternative, particularly in cases of moderate to advanced keratoconus with Kmax <75D.