Outcome Of Refractive Surgery Research Articles

A Comprehensive Study on Elasticity and Viscosity in Biomechanics and Optical Properties of the Living Human Cornea

Corneal biomechanics is a hot topic in ophthalmology. The biomechanical properties (BMPs) of the cornea have important implications in the management and diagnosis of corneal diseases such as ectasia and keratoconus. In addition, the characterization of BMPs is crucial to model the predictability of a corneal surgery intervention, the outcomes of refractive surgery or the follow-up of corneal diseases. The biomechanical behavior of the cornea is governed by viscoelastic properties that allow, among other structural implications, the damping of excess intraocular pressure and the reduction of damage to the optic nerve. Currently, the most versatile and complete methods to measure corneal viscoelasticity are based on air-puff corneal applanation. However, these methods lack the ability to directly measure corneal viscosity. The aim of this work is to propose a new methodology based on the analysis of corneal air-puff measurements through the standard linear solid model (SLSM) to provide analytical expressions to separately calculate the elastic and time-dependent (corneal retardation time and viscosity) properties. The results show the mean values of elasticity (E), viscosity (Ƞ) and corneal retardation time (τ) in a sample of 200 young and healthy subjects. The influence of elasticity and viscosity on viscoelasticity, high-order corneal aberrations and optical transparency is investigated. Finally, the SLSM fed back from experimental E and Ƞ values is employed to compare the creep relaxation response between a normal, an ocular hypertension patient and an Ortho-K user. Corneal biomechanics is strongly affected by intraocular pressure (IOP); however, corneal hysteresis (CH) analysis is not enough to be employed as a risk factor of glaucoma progression. Low values of CH can be accompanied by high or low corneal elasticity and viscosity depending on the IOP threshold from which the time-dependent biomechanical properties trends are reversed.

Corneal Stroma Analysis and Related Ocular Manifestations in Recovered COVID-19 Patients.

The purpose of this study was to assess the impact of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) on corneal stroma characteristics, ocular manifestations, and post-recovery refractive surgery outcomes after varying recovery durations. Fresh corneal lenticules from patients with post-coronavirus disease 2019 (COVID-19; recovered within 135days) and healthy controls (HCs) after small incision lenticule extraction (SMILE) surgery were obtained for experimental validation of SARS-CoV-2 susceptibility, morphological changes, and immune response of the corneal stroma. Corneal optical density (CD) was measured using the Pentacam HR. Corneal epithelium thickness (ET) and endothelium parameters were evaluated by wide-field optical coherence tomography (OCT) and non-contact specular microscopy (SP-1P), respectively. All the patients were assessed after SMILE surgery until 3 month of follow-up. The cornea was susceptible to SARS-CoV-2 with the presence of SARS-CoV-2 receptors (CD147 and ACE2) and spike protein remnants (4 out of 58) in post-recovery corneal lenticules. Moreover, SARS-CoV-2 infection triggered immune responses in the corneal stroma, with elevated IL-6 levels observed between 45 and 75days post-recovery, which were then lower at around day 105. Concurrently, corneal mid-stromal nerve length and branching were initially higher in the 60D to 75D group and returned to control levels by day 135. A similar trend was observed in CD within zones 0 to 2 and 2 to 6 and in the hexagonal cells (HEX) ratio in endothelial cells, whereas ET remained consistent. Notably, these changes did not affect the efficacy, safety, or predictability of post-recovery SMILE surgery. SARS-CoV-2 induces temporal alterations in corneal stromal morphology and function post-recovery. These findings provided a theoretical basis for corneal health and refractive surgery management in the post-COVID-19 milieu.

Comparative Analysis of Visual Outcomes and Complications in Intraocular Collamer Lens, Small-Incision Lenticule Extraction, and Laser-Assisted In Situ Keratomileusis Surgeries: A Comprehensive Review.

This review provides a comparative analysis of visual outcomes and complications associated with three prominent refractive surgical techniques: intraocular collamer lens (ICL) implantation, small-incision lenticule extraction (SMILE), and laser-assisted in situ keratomileusis (LASIK). Refractive surgeries aim to correct myopia, hyperopia, and astigmatism, offering patients an alternative to corrective lenses. The review highlights the importance of comparing these procedures to guide clinical decision-making effectively. Each technique is described, emphasizing its unique advantages and considerations. While LASIK remains widely favored for its rapid visual recovery and high patient satisfaction, ICL is suitable for patients with higher refractive errors or corneal irregularities. Although relatively newer, SMILE shows promise with potential benefits such as corneal biomechanical stability and a reduced risk of dry eye syndrome. However, each procedure carries its distinct complications, reinforcing the need for personalized patient care and informed decision-making. Understanding these techniques' relative efficacy and safety profiles is essential for optimizing outcomes and enhancing patient satisfaction. Continued advancements in technology and surgical techniques promise further improvements in refractive surgery outcomes, underscoring the importance of ongoing research and innovation.

Artificial intelligence in cataract and refractive surgery

Artificial intelligence (AI) technology is proving to be promising in the field of healthcare, especially in the areas relying on big data and image‐based analysis. In Ophthalmology, AI was already tested in majority of subspecialities, including cataract and refractive surgery. There were interesting studies showing the benefits of using AI algorithms in early keratoconus detection, to predict the outcomes of laser refractive surgery, and to cataract surgery training and monitoring. Moreover, AI models using fundus images to diagnose and grade cataract have been developed. New intraocular lens (IOL) formulas are applying big data and computational methodologies to achieve better prediction of targeted refraction and simplify the IOL selection process. Recent developments in AI have shown their potential possibility for the diagnosis and management of paediatric cataract using slit‐lamp images.

Understanding Variable Biologic-Based Factors in Determining Laser Refractive Surgery Outcomes: A Response to the Moshirfar et al Paper [Response to Letter

Understanding Variable Biologic-Based Factors in Determining Laser Refractive Surgery Outcomes: A Response to the Moshirfar et al Paper [Response to Letter

Bibliometric and visualized analysis of myopic corneal refractive surgery research: from 1979 to 2022.

Myopic corneal refractive surgery is one of the most prevalent ophthalmic procedures for correcting ametropia. This study aimed to perform a bibliometric analysis of research in the field of corneal refractive surgery over the past 40 years in order to describe the current international status and to identify most influential factors, while highlighting research hotspots. A bibliometric analysis based on the Web of Science Core Collection (WoSCC) was used to analyze the publication trends in research related to myopic corneal refractive surgery. VOSviewer v.1.6.10 was used to construct the knowledge map in order to visualize the publications, distribution of countries, international collaborations, author productivity, source journals, cited references, keywords, and research hotspots in this field. A total of 4,680 publications on myopic corneal refractive surgery published between 1979 and 2022 were retrieved. The United States has published the most papers, with Emory University contributing to the most citations. The Journal of Cataract and Refractive Surgery published the greatest number of articles, and the top 10 cited references mainly focused on outcomes and wound healing in refractive surgery. Previous research emphasized "radial keratotomy (RK)" and excimer laser-associated operation methods. The keywords containing femtosecond (FS) laser associated with "small incision lenticule extraction (SMILE)" and its "safety" had higher burst strength, indicating a shift of operation methods and coinciding with the global trends in refractive surgery. The document citation network was clustered into five groups: (1) outcomes of refractive surgery: (2) preoperative examinations for refractive surgery were as follows: (3) complications of myopic corneal refractive surgery; (4) corneal wound healing and cytobiology research related to photorefractive laser keratotomy; and (5) biomechanics of myopic corneal refractive surgery. The bibliometric analysis in this study may provide scholars with valuable to information and help them better understand the global trends in myopic corneal refractive surgery research frontiers. Two stages of rapid development occurred around 1991 and 2013, shortly after the innovation of PRK and SMILE surgical techniques. The most cited articles mainly focused on corneal wound healing, clinical outcomes, ocular aberration, corneal ectasia, and corneal topography, representing the safety of the new techniques.

Human cornea thermo-viscoelastic behavior modelling using standard linear solid model

BackgroundCorneal biomechanics is of great interest to researchers recently. Clinical findings relate them to corneal diseases and to outcomes of refractive surgery. To have a solid understanding of corneal diseases’ progression, it is important to understand corneal biomechanics. Also, they are essential for better explaining outcomes of refractive surgeries and their undesired consequences. There is a difficulty for studying corneal biomechanics in-vivo and multiple limitations arise for ex-vivo studies. Hence mathematical modelling is considered as a proper solution to overcome such obstacles. Mathematical modelling of cornea in-vivo allows studying corneal viscoelasticity with taking into consideration all boundary conditions existing in real in-vivo situation.MethodsThree mathematical models are used to simulate corneal viscoelasticity and thermal behavior in two different loading situations: constant and transient loading. Two models of the three are used for viscoelasticity simulation which are Kelvin-Voigt and standard linear solid models. Also, temperature rise due to the ultrasound pressure push is calculated using bioheat transfer model for both the axial direction and as a 2D spatial map using the third model (standard linear solid model).ResultsViscoelasticity simulation results show that standard linear solid model is efficient for describing the viscoelastic behavior of human cornea in both loading conditions. Results show also that the deformation amplitude obtained from standard linear solid model is more reasonable for corneal soft-tissue deformation with respect to corresponding clinical findings than that obtained from Kelvin-Voigt model. Thermal behavior results estimated corneal temperature rise to be roughly 0.2 °C, which conforms with FDA regulations for soft tissue safety.ConclusionStandard Linear Solid (SLS) model is better describing the human corneal behavior in response to constant and transient load more efficiently. Temperature rise (TR) for the corneal tissue of about 0.2 °C is conforming with FDA regulations and even less than the FDA regulations for soft tissue safety.

MEYEstro software: an automatic tool for standardized refractive surgery outcomes reporting

BackgroundStandardization for reporting medical outcomes enables clinical study comparisons and has a fundamental role in research reproducibility. In this context, we present mEYEstro, a free novel standalone application for automated standardized refractive surgery graphs. mEYEstro can be used for single and multiple group comparisons in corneal and intraocular refractive surgery patients. In less than 30 s and with minimal user manipulation, mEYEstro automatically creates the required journal standard graphs while simultaneously performing valid statistical analyses.ResultsThe software produces the following 11 standard graphs; Efficacy: 1. Cumulative uncorrected (UDVA) and corrected visual acuity (CDVA), 2. Difference between UDVA and CDVA, Safety: 3. Change in line of CDVA, Accuracy: 4. Spherical equivalent (SEQ) to intended target, 5. Attempted vs. achieved SEQ, 6. Defocus equivalent (DEQ) accuracy, 7. Refractive astigmatism accuracy, 8. Target-induced astigmatism vs. Surgically-induced astigmatism, 9. Correction index histogram, 10. Angle of error histogram, Stability: 11. SEQ stability over time. Percent proportions, means, standard deviations, Cohen's d effect sizes, and p-values are calculated and displayed on each graph. All graphs can be easily exported as high-resolution TIFF images for figures to use in scientific manuscripts and presentations.ConclusionsmEYEstro software enables clinicians, surgeons, and researchers, to easily and efficiently analyze refractive surgery outcomes using the standardized methodology required by several peer-reviewed ophthalmology journals.

Laser in situ keratomileusis and surface ablation in pregnancy

Although corneal refractive surgery is contraindicated during pregnancy, some patients are unaware that they are pregnant when they undergo surgery. Our objectives were to determine the functional outcomes of corneal refractive surgery during pregnancy and to compare the results with those of nonpregnant women. We performed a multicenter, retrospective, interventional case series review of patients who were pregnant and who underwent laser in situ keratomileusis (LASIK) or surface ablation (photorefractive keratectomy, PRK) from September 11, 2002 to December 12, 2020 (group 1, n=82 eyes). Patients were included consecutively. Findings were compared with those of nonpregnant women (group 2, n=164 eyes). Functional (visual and refractive) outcomes are described. Follow-up was at least 550 days (control group, median [IQR], 990 days [715-1496]; study group, 895 days [709-1310]). The setting was Clínica Baviera, Spain, (AIER Eye Hospital Group). A statistically significant difference was found between the groups in terms of efficacy index (EI). No complications of pregnancy or labor were reported. Similarly, a search of medical records revealed no adverse effects in the infants. To the best of our knowledge, this is the first case series on pregnancy and refractive surgery. We do not recommend performing LASIK or surface ablation on pregnant women. Our objective in the present study was to present relevant scientific data obtained from women who underwent refractive surgery while unaware that they were pregnant.

Surface Refractive Surgery Outcomes in Israeli Combat Pilots

Photorefractive keratectomy (PRK) has long been the method of choice for refractive surgery in pilots, and was FDA approved for U.S. Air Force aviators in 2000. We retrospectively reviewed the medical records of 16 male combat pilots (mean age 25.0 ± 5.5 years) who had undergone bilateral laser refractive surgery with surface ablation (alcohol-assisted PRK: 81.25%, transepithelial-PRK: 18.75%), and who had a mean baseline spherical equivalent (SE) of −2.1 ± 0.7 D in the right eye, and −2.0 ± 0.7 D in the left. The mean follow-up was 8.4 ± 6.6 months. On the last visit, the uncorrected visual acuity (UCVA) had improved from 0.75 ± 0.33 logMar to −0.02 ± 0.03 logMar (p < 0.001), and from 0.72 ± 0.36 logMar to −0.02 ± 0.05 logMar (p < 0.001), for the right and left eyes, respectively. The percentages of participants with a right eye UCVA of at least 0.0, −0.08, and −0.18 logMAR (6/6, 6/5, and 6/4 Snellen in meters) were 100%, 37.5%, and 6.2%, respectively, and for the left eye, 93.7%, 43.75%, and 6.2%, respectively. No complications occurred. This is the first study to assess refractive surgery outcomes in a cohort of Israeli combat pilots. Surface refractive surgery effectively improved UCVA and reduced spectacle reliance for the members of this visually demanding profession.

SMILE for Hyperopia With and Without Astigmatism: Results of a Prospective Multicenter 12-Month Study

To investigate the safety and effectiveness of small incision lenticule extraction (SMILE) in patients who have hyperopia with or without astigmatism. This was a prospective multicenter trial including 374 eyes of 199 patients treated by SMILE for hyperopia using the VisuMax femtosecond laser (Carl Zeiss Meditec AG). Inclusion criteria were sphere up to +6.00 diopters (D), cylinder up to 5.00 D, and maximum hyperopic meridian up to +7.00 D, with preoperative corrected distance visual acuity (CDVA) of 20/25 or better. The optical zone was 6.3 mm with a transition zone of 2 mm. The minimum lenticule thickness was set at 25 µm in the center and at 10 µm at the edge. Patients were examined at 1 day, 1 week, and 1, 3, 6, 9, and 12 months after surgery. Standard refractive surgery outcomes analysis was performed. The preoperative spherical equivalent was +3.20 ± 1.48 D (range: +0.25 to +6.50 D). At the 12-month follow-up visit, 81% of eyes treated were within ±0.50 D and 93% of eyes were within ±1.00 D of intended correction. A total of 1.2% of eyes lost two or more lines of CDVA at the 12-month follow-up visit, and 83% were at least 20/20, corresponding to a safety index of 1.005 at 12 months. Of the 219 eyes with plano target, 68.8% had an uncorrected distance visual acuity of 20/20 or better and 88% were at least 20/25 uncorrected at 12 months. There were no statistically significant changes in contrast sensitivity. SMILE was found to be an effective treatment method for the correction of compound hyperopic astigmatism, demonstrating a high level of efficacy, predictability, safety, and stability. [J Refract Surg. 2022;38(12):760-769.].

A detailed methodology to model the Non Contact Tonometry: a Fluid Structure Interaction study.

Understanding the corneal mechanical properties has great importance in the study of corneal pathologies and the prediction of refractive surgery outcomes. Non-Contact Tonometry (NCT) is a non-invasive diagnostic tool intended to characterize the corneal tissue response in vivo by applying a defined air-pulse. The biomarkers inferred from this test can only be considered as indicators of the global biomechanical behaviour rather than the intrinsic biomechanical properties of the corneal tissue. A possibility to isolate the mechanical response of the corneal tissue is the use of an inverse finite element method, which is based on accurate and reliable modelling. Since a detailed methodology is still missing in the literature, this paper aims to construct a high-fidelity finite-element model of an idealized 3D eye for in silico NCT. A fluid-structure interaction (FSI) simulation is developed to virtually apply a defined air-pulse to a 3D idealized eye model comprising cornea, limbus, sclera, lens and humors. Then, a sensitivity analysis is performed to examine the influence of the intraocular pressure (IOP) and the structural material parameters on three biomarkers associated with corneal deformation. The analysis reveals the requirements for the in silico study linked to the correct reproduction of three main aspects: the air pressure over the cornea, the biomechanical properties of the tissues, and the IOP. The adoption of an FSI simulation is crucial to capture the correct air pressure profile over the cornea as a consequence of the air-jet. Regarding the parts of the eye, an anisotropic material should be used for the cornea. An important component is the sclera: the stiffer the sclera, the lower the corneal deformation due to the air-puff. Finally, the fluid-like behavior of the humors should be considered in order to account for the correct variation of the IOP during the test which will, otherwise, remain constant. The development of a strong FSI tool amenable to model coupled structures and fluids provides the basis to find the biomechanical properties of the corneal tissue in vivo.

Long-term efficacy and safety profiles after posterior chamber phakic intraocular lens implantation in eyes with more than 10 years of follow-up.

To evaluate long-term efficacy, safety, predictability, and stability of a posterior chamber phakic intraocular lens (Visian implantable collamer lens [ICL]) in eyes with ≥10 years of follow-up. Instituto de Microcirugía Ocular, Barcelona, Spain. Retrospective study. Eyes undergoing ICL implantation from 2008 to 2011 with ≥10 years of follow-up were included. Variables analyzed were preoperative, 1-month, 1-year, 5-year, and last follow-up uncorrected distance (UDVA) and corrected distance visual acuity (CDVA), manifest refraction, spherical equivalent (SE), endothelial cell count (ECC), and intraocular pressure (IOP). Descriptive statistics were performed and results reported following the Standard for Reporting Refractive Surgery Outcomes. 45 eyes (26 patients) were analyzed; the mean follow-up 11.35 ± 1.30 years. The mean preoperative SE was -10.06 ± 3.40 diopters (D) and the mean preoperative cylinder -1.55 ± 1.45 D. At the last follow-up, efficacy and safety indices were 0.79 and 1.12, respectively. In total, 32 eyes (71%) achieved an UDVA of ≥20/40. 22 eyes (49%) gained ≥1 line of CDVA, and 2 eyes (4%) lost ≥2 lines of CDVA. At the final follow-up, 19 eyes (42%) and 29 eyes (64%) were within ±0.50 D and ±1.00 D of attempted SE correction, respectively. 31 eyes (69%) had ≤1.00 D of postoperative astigmatism, and 29 eyes (74%) were within ±15 degrees from the intended correction axis. At the last visit, a statistically significant myopic progression of -0.75 ± 1.20 D was observed ( P = .01). ECC loss at the last follow-up was 9.85 ± 11.35%. IOP remained stable. There were no intraoperative complications. 3 eyes (7%) developed cataract after 10 years. The long-term results demonstrated that ICL was effective, predictable, stable, and safe.

Long-term efficacy and safety profiles of iris-fixated foldable anterior chamber phakic intraocular lens implantation in eyes with more than 10 years of follow-up.

To evaluate the long-term efficacy, safety, predictability, and stability of a foldable anterior chamber phakic intraocular lens (pIOL) (Artiflex) implantation in eyes with more than 10 years of follow-up. Instituto de Microcirugía Ocular, Barcelona, Spain. Retrospective study. Patients who underwent Artiflex pIOL implantation during 2008 to 2011 and with more than 10 years of follow-up were included. Variables analyzed were as follows: uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, spherical equivalent (SE), endothelial cell count (ECC), and intraocular pressure (IOP) preoperatively and at 1 month, 1 year, 5 years, and the final follow-up. Descriptive statistics were performed and results reported following the Standard for Reporting Refractive Surgery Outcomes. 76 eyes (40 patients) were analyzed, and the mean follow-up was 10.67 ± 0.64 years. The mean preoperative SE was -8.26 ± 2.47 diopters (D), and the mean preoperative cylinder was -0.95 ± 0.86 D. At the final follow-up, efficacy and safety indices were 0.82 and 1.11, respectively. In total, 58 eyes (76%) achieved a UDVA of ≥20/40. 30 eyes (39%) gained ≥1 line of CDVA, and no eye lost ≥2 lines of CDVA. At the final follow-up, 46 (61%) and 58 (76%) eyes were within ±0.50 D and ±1.00 D of attempted SE correction, respectively. 72 eyes (95%) had ≤1.00 D of postoperative astigmatism, and 46 eyes (61%) were within ±15 degrees from the intended correction axis. At the last visit, a statistically significant myopic progression of -0.56 ± 0.83 D was observed ( P = .01). The mean ECC loss at the final follow-up was 12.2 ± 12.5%. IOP remained stable. Two eyes (2.63%) developed cataract after 10.3 years. Long-term results demonstrated that Artiflex pIOL implantation was effective, predictable, stable, and safe.

On the Relationship between Corneal Biomechanics, Macrostructure, and Optical Properties.

Optical properties of the cornea are responsible for correct vision; the ultrastructure allows optical transparency, and the biomechanical properties govern the shape, elasticity, or stiffness of the cornea, affecting ocular integrity and intraocular pressure. Therefore, the optical aberrations, corneal transparency, structure, and biomechanics play a fundamental role in the optical quality of human vision, ocular health, and refractive surgery outcomes. However, the inter-relationships of those properties are not yet reported at a macroscopic scale within the hierarchical structure of the cornea. This work explores the relationships between the biomechanics, structure, and optical properties (corneal aberrations and optical density) at a macro-structural level of the cornea through dual Placido–Scheimpflug imaging and air-puff tonometry systems in a healthy young adult population. Results showed correlation between optical transparency, corneal macrostructure, and biomechanics, whereas corneal aberrations and in particular spherical terms remained independent. A compensation mechanism for the spherical aberration is proposed through corneal shape and biomechanics.

Outcomes of a Toric Monofocal Piggyback Intraocular Lens for Residual Astigmatic Refractive Error in Pseudophakic Eyes

ABSTRACTPurpose/AimTo evaluate the visual outcomes, refractive outcomes and rotational stability of a toric piggyback intraocular lens (1stQ AddOn, GmbH, Mannheim, Germany) for astigmatic refractive error in pseudophakic eyes.Materials and MethodsVisual and refractive outcomes were assessed based on the standard graphs for reporting refractive surgery outcomes. Rotational stability was assessed according to the Intraocular Lens (IOL) standards of the International Organisation for Standards.ResultsTwenty-two eyes of 17 patients (age: 65.1 ± 9.3 years) underwent toric piggyback IOL insertion. After a minimum follow-up of 3 months, 18 eyes (82%) achieved an uncorrected distance visual acuity (UDVA) of 0.00 logMAR (20/20) or better and all eyes achieved 0.1 logMAR (20/25). Mean UDVA improved from 0.27 ± 0.03 to 0.12 ± 0.03 and 0.04 ± 0.04 at one and 3 months (all p < .05). Nineteen eyes (86%) achieved an UDVA at least equal to the pre-operative corrected distance visual acuity (CDVA). No eyes lost more than one line of CDVA. All eyes achieved within 0.5D of target spherical equivalent (SE). In 18 eyes (82%), the residual astigmatism magnitude was 0.5D or less. The mean absolute difference between the target axis and the achieved axis 1 and 3 months postoperatively was 2.5° ± 2.7° and 3.2° ± 3.3°, respectively. The final IOL orientation was within 10 degrees of target axis in 19 of 22 (86.4%) eyes, within 20 degrees in 21 of 22 (95.2%) eyes and within 30 degrees in 22 of 22 (100%) eyes. IOL rotational repositioning was required in two eyes (9.1%).ConclusionsIn this cohort of patients, the 1stQ AddOn toric monofocal piggyback IOL resulted in very good visual and refractive outcomes and showed reasonable rotational stability. This IOL appears to be an effective treatment option for residual astigmatic refractive error in pseudophakic eyes.

Controversy and Consideration of Refractive Surgery in Patients with Heritable Disorders of Connective Tissue.

Heritable Disorders of Connective Tissue (HDCTs) are syndromes that disrupt connective tissue integrity. They include Osteogenesis Imperfecta (OI), Ehlers Danlos Syndrome (EDS), Marfan Syndrome (MFS), Loeys-Dietz Syndrome (LDS), Epidermolysis Bullosa (EB), Stickler Syndrome (STL), Wagner Syndrome, and Pseudoxanthoma Elasticum (PXE). Because many patients with HDCTs have ocular symptoms, commonly myopia, they will often present to the clinic seeking refractive surgery. Currently, corrective measures are limited, as the FDA contraindicates laser-assisted in-situ keratomileusis (LASIK) in EDS and discourages the procedure in OI and MFS due to a theoretically increased risk of post-LASIK ectasia, poor wound healing, poor refractive predictability, underlying keratoconus, and globe rupture. While these disorders present with a wide range of ocular manifestations that are associated with an increased risk of post-LASIK complications (e.g., thinned corneas, ocular fragility, keratoconus, glaucoma, ectopia lentis, retinal detachment, angioid streaks, and ocular surface disease), their occurrence and severity are highly variable among patients. Therefore, an HDCT diagnosis should not warrant an immediate disqualification for refractive surgery. Patients with minimal ocular manifestations can consider LASIK. In contrast, those with preoperative signs of corneal thinning and ocular fragility may find the combination of collagen cross-linking (CXL) with either photorefractive keratotomy (PRK), small incision lenticule extraction (SMILE) or a phakic intraocular lens (pIOL) implant to be more suitable options. However, evidence of refractive surgery performed on patients with HDCTs is limited, and surgeons must fully inform patients of the unknown risks and complications before proceeding. This paper serves as a guideline for future studies to evaluate refractive surgery outcomes in patients with HDCTs.

Customized eye modeling for optical quality assessment in myopic femto-LASIK surgery

Refractive surgery is recognized as an effective method for myopia treatment, but it can induce night vision disturbances such as glare. We present an eye modeling method for the optical quality assessment in response to the structural changes in the eyes by femto-LASIK surgery. Customized eye models were built from the measurements of 134 right eyes pre- and post-operatively. Optical performance was evaluated using spot diagrams, point spread functions (PSFs), modulation transfer functions (MTFs), and chromatic aberrations at various fields (0°–30°), different pupil diameters (2–6 mm), and initial myopias (− 1.25 to − 10.5 D). Pupil size and initial myopia are the two major factors that affect visual performance of post-operative eyes. The results of spot diagrams, PSFs, and MTFs indicated that post-operative visual performance deteriorated as the visual field and pupil size increased, and it was significantly influenced by initial myopia. Post-operative chromatic aberrations were also affected by initial myopia. As pupil size increased, the post-operative longitudinal chromatic aberrations tended to decrease slightly, while the transverse chromatic aberrations remained similar. The use of eye modeling for refractive surgery assessment could possibly provide a more personalized surgical approach, could improve the prediction accuracy of refractive surgery outcomes, and promote the invention and development of better surgical methods.

Laser refractive surgery in pregnant or breastfeeding patients.

This systematic review reported the outcomes of laser corneal refractive surgery in pregnant or breastfeeding patients. This study was performed by searching in PubMed, Web of Science, and Scopus databases, on June 15, 2020. Included were 128 eyes from a total of 64 patients, with the mean maximum follow-up was 39.2 ± 36.14 months. Time from surgery to complication ranged from 1 to 67 months, with a mean value of 23.42 ± 22.23 months. Photorefractive keratectomy and laser in situ keratomileusis surgery seem to be stable procedures that are not modified during pregnancy and safe to complete during breastfeeding. Nevertheless, the lack of weight prospective research avoids having a greater certainty on this matter, and because of transitory nature of pregnancy and breastfeeding, it could still be contemplated that surgery risk outweigh the benefits. Additional investigation will be necessary to clarify these issues.

Comparison of outcomes of laser refractive surgery (LRS) alone and LRS with laser asymmetric keratectomy in patients with myopia: A retrospective study.

To compare and analyze the postoperative 1-year outcomes of laser refractive surgery (LRS) alone vs LRS with laser asymmetric keratectomy (LAK), in patients with myopia, for preventing and resolving LRS complications.This retrospective study compared the preoperative and 1-year postoperative outcomes between the control and comparison groups using a sum of deviations in corneal thickness in 4 directions >80 μm. The control group included 41 patients with myopia (41 eyes) who underwent LRS. The comparison group included 33 patients (33 eyes) who received LAK-linked LRS. Age, spherical equivalent (SE), sphere, cylinder, uncorrected distance visual acuity (UDVA), pupil size, kappa angle, central corneal thickness, corneal irregularity in the 3.0 mm zone on Orbscan maps (SUM), distance between the maximum posterior elevation (best-fit-sphere) and the visual axis (DISTANCE), postoperative blurring scores, frequency of postoperative myopic regression, and efficiency index were compared.Preoperative age (P = .198), SE (P = .686), sphere (P = .562), cylinder (P = .883), UDVA (P = .139), pupil size (P = .162), kappa angle (P = .807), central corneal thickness (P = .738), corneal irregularity (P = .826), SUM (P = .774), and DISTANCE (P = .716) were similar between the 2 groups. The 1-year postoperative SE (P = .024), sphere (P = .022), corneal irregularity (P = .033), SUM (P = .000), DISTANCE (P = .04), blurring scores (P = .000), and frequency of postoperative myopic regression (P = .004) were significantly decreased in the comparison group compared to the control group. UDVA (P = .014) and the efficiency index (P = .035) were higher in the comparison group.LAK with LRS improved corneal symmetry by reducing the SUM and DISTANCE. UDVA and efficiency index were also improved and blurring and myopic regression were reduced postoperatively.