Explore the vast range of titles available.

This prospective observational study comprehensively characterized the normative distribution of corneal epithelial thickness using 9-mm spectral-domain optical coherence tomography (SD-OCT) maps. Data were collected from 283 eyes of refractive surgery candidates who underwent a complete ophthalmologic evaluation, including SD-OCT imaging. The analysis revealed a mean central corneal epithelial thickness of 53.34 μm (SD ± 3.26 μm), exhibiting a heterogeneous distribution with significantly thicker measurements in inferior compared to superior regions. This distribution followed a Gaussian pattern, with the thickest measurements consistently observed in the central and inferior regions. The study also revealed statistically significant differences in central corneal epithelial thickness between males (54.11 μm) and females (52.64 μm). A weak but significant negative correlation was observed between superior epithelial thickness and age. This detailed analysis of corneal epithelial thickness across multiple zones within a large sample provides valuable normative data essential for clinical practice and future research in corneal pathology. The established normative reference values are critical for accurately identifying deviations in epithelial thickness associated with conditions such as keratoconus.

Purpose: To critically reassess the scientific foundation of the 400-μm minimum corneal thickness threshold for endothelial safety in standard corneal cross-linking (CXL) with 3 mW/cm2 ultraviolet A (UVA) irradiation. Methods: A comprehensive analysis of the foundational studies that established this limit was conducted, with a focus on their methodological assumptions, modeling strategies, and translational weaknesses. Particular attention was given to the use of optical attenuation equations, riboflavin pharmacokinetics, and evolving imaging practices. Results: The 400-μm threshold is derived from two seminal studies (one in vitro, one in vivo) that applied fixed assumptions about riboflavin concentration and stromal uniformity. Notably, the models used the Exponential Attenuation law and not the Lambert-Beer law, as opposed to what is frequently cited, to estimate UVA penetration. These estimations relied on simplified optical parameters, such as a uniform attenuation coefficient (μ = 53 cm−1), without accounting for depth-dependent chromophore gradients, scattering, or biological variability. Moreover, the original threshold did not anticipate subsequent changes in riboflavin formulation and concentration, the use of alternative vehicles such as hydroxypropyl methylcellulose, or the emergence of accelerated and customized CXL protocols—factors that materially alter stromal pharmacokinetics and photochemical response. Conclusions: The 400-μm guideline, although historically influential, is conceptually fragile. To establish a scientifically robust safety threshold in CXL, future models must incorporate validated attenuation coefficients, experimentally defined riboflavin diffusion dynamics, and patient-specific stromal properties. A more precise, data-driven framework is needed to support individualized decision-making, especially for CXL in thin corneas.

Graft versus H\\host disease (GVHD) can be a devastating complication following bone marrow transplantation. Acute or chronic systemic GVHD can be lethal, and severe damage of different organs and tissues can occur with both types of GVHD. Ocular involvement, either in an acute or chronic presentation, may range from mild to severe with accompanying vision loss present in 60–90 % of patients. Chronic ocular GVHD, the most common form of GVHD, affects mainly the lacrimal gland, meibomian glands, cornea and conjunctiva, mimicking other immunologically mediated inflammatory diseases of the ocular surface without specific symptoms or signs. However, dry eye disease is the main manifestation of GVHD. The long-term treatment of ocular GVHD continues to be challenging and involves a multidisciplinary approach wherein the ophthalmologist plays a major role. Besides systemic immunosuppression and ocular lubricants, topical steroids and topical cyclosporine are commonly prescribed. Newer therapeutic interventions for moderate and severe ocular GVHD include the use of serum eye drops and scleral contact lenses. In this manuscript, we review the mechanisms, clinical findings, and treatment of ocular GVHD.

PURPOSE: To investigate the association of the percent tissue altered (PTA) with the occurrence of ectasia after LASIK in eyes with suspicious preoperative corneal topography. METHODS: This retrospective comparative case–control study compared associations of reported ectasia risk factors in 129 eyes, including 57 eyes with suspicious preoperative Placido-based corneal topography that developed ectasia after LASIK (suspect ectasia group), 32 eyes with suspicious topography that remained stable for at least 3 years after LASIK (suspect control group), and 30 eyes that developed ectasia with bilateral normal topography (normal topography ectasia group). Groups were subdivided based on topographic asymmetry into high- or low-suspect groups. The PTA, preoperative central corneal thickness (CCT), residual stromal bed (RSB), and age (years) were evaluated in univariate and multivariate analyses. RESULTS: Average PTA values for normal topography ectasia (45), low-suspect ectasia (39), high-suspect ectasia (36), low-suspect control (32), and high-suspect control (29) were significantly different from one another in all comparisons (Average PTA values for normal topography ectasia (45), low-suspect ectasia (39), high-suspect ectasia (36), low-suspect control (32), and high-suspect control (29) were significantly different from one another in all comparisons ( P < .003) except high- and low-suspect ectasia groups ( P = .033), and presented the highest discriminative capability of all variables evaluated. Age was only significantly different between the high-suspect ectasia and normal topography ectasia groups, and CCT was not significantly different between any groups. Stepwise logistic regression revealed the PTA as the most significant independent variable ( P < .0001), with RSB the next most significant parameter. CONCLUSIONS: There remains a significant correlation between PTA values and ectasia risk after LASIK, even in eyes with suspicious corneal topography. Less tissue alteration, or a lower PTA value, was necessary to induce ectasia in eyes with more remarkable signs of topographic abnormality, and PTA provided better discriminative capabilities than RSB for all study populations. [[ J Refract Surg. 2015:31(4):258–265.]

PURPOSE: To report two cases of significant flattening after corneal cross-linking (CXL) for keratoconus and discuss its potential explanations and implications. METHODS: Observational case report. RESULTS: One year after standard CXL protocol (3 mW/cmOne year after standard CXL protocol (3 mW/cm 2 for 30 minutes and total energy of 5.4 J/cm 2 ), a 28-year-old woman presented a flattening of greater than 14 diopters and a 14-year-old boy presented a flattening of 7 diopters. CONCLUSIONS: Although rare, a significant flattening effect may occur during the first year after CXL, probably related to intense wound healing, increase in corneal elasticity, CXL effective depth, and central cone location. These cases suggest the necessity of a patient-specific approach and a better understanding regarding the actual mechanism behind its potent effect. [[ J Refract Surg. 2015;31(6):419–422.]

Introduction: Topical losartan has emerged as a promising therapeutic option for preventing and treating corneal scarring fibrosis. Its mechanism of action involves the inhibition of ERK-mediated signaling in the noncanonical TGF-beta pathways, promoting apoptosis of myofibroblasts and facilitating a return of corneal transparency. While numerous studies in rabbits and several human case reports have demonstrated its efficacy and safety, published data on its use in clinical scenarios remain limited. This study presents 3 cases where topical losartan successfully treated corneal scarring induced by herpes simplex virus (HSV) or varicella-zoster virus (VZV) keratitis. Case Presentations: Three patients (ages 40, 38, 15 years) with corneal scarring and vision loss from HSV or VZV keratitis were treated with topical 0.8 mg/mL losartan 6 times a day for 4–9 months, depending on the clinical response, after failing traditional management with corticosteroids. Best spectacle-corrected vision and slit-lamp corneal opacity improved in each case. Anterior segment OCT documented improved stromal opacity in 1 case. Conclusions: Topical losartan, a known inhibitor of fibrotic TGF-beta signaling, is potentially an effective alternative in the treatment of stromal scarring fibrosis caused by corneal HSV and VZV infections. Patients with HSV- or VZV keratitis-induced corneal scarring may be ideal candidates for planned clinical trials of the efficacy and safety of topical losartan treatment.

PURPOSE: To provide an overview of the clinical results of different ablation profiles based on wavefront technology and discuss their characteristics and limitations. METHODS: Literature review of studies reporting results of ablation profiles based on wavefront technology in virgin healthy eyes. RESULTS: Over the past 10 years, a large number of studies comparing different treatment algorithms and newer excimer laser platforms have been published. Thirty-six clinical studies including 3637 eyes analyzing the clinical results obtained after wavefront-guided, wavefront-optimized, and Q-factor profiles have been reviewed. Although wavefront-driven profiles allowed reduction of the amount of induced optical aberrations with conventional ablations, thereby improving the quality of vision, it appears that no algorithm of treatment or excimer laser platform has demonstrated a clear superiority over another. Wound healing and unexpected biomechanical response to surgery affect the accuracy of customized treatments and produce variable results. In addition, it is difficult to rigorously analyze and compare findings among different studies because of the diverse variety in which the data are reported. CONCLUSIONS: Despite several technological improvements over the years, wavefront ablation profiles have not consistently demonstrated superiority in terms of visual acuity and lower order aberrations compared to the standard procedure, although the induction of higher order aberrations has been reduced. The concept of an individualized eye model has emerged recently, based on the optical ray tracing algorithm, and could theoretically provide a higher level of customization, thus fulfilling the promise of “super vision.”

PURPOSE: To provide an overview of the recent advances concerning the corneal molecular and cellular biology processes involved in the wound healing response after excimer laser surface ablation and LASIK surgery. METHODS: Literature review. RESULTS: The corneal wound healing response is a complex cascade of events that impacts the predictability and stability of keratorefractive surgical procedures such as photorefractive keratectomy and LASIK. The generation and persistence of corneal myofibroblasts (contractile cells with reduced transparency) arise from the interaction of cytokines and growth factors such as transforming growth factor beta and interleukin 1 produced by epithelial and stromal cells in response to the corneal injury. Myofibroblasts, and the opaque extracellular matrix they secrete into the stroma, disturb the precise distribution and spacing of collagen fibers related to corneal transparency and lead to the development of vision-limiting corneal opacity (haze). The intact epithelial basement membrane has a pivotal role as a structure that regulates corneal epithelial–stromal interactions. Thus, defective regeneration of the epithelial basement membrane after surgery, trauma, or infection leads to the development of stromal haze. The apoptotic process following laser stromal ablation, which is proportional to the level of attempted correction, leads to an early decrease in anterior keratocyte density and the diminished contribution of these non-epithelial cells of components such as perlecan and nidogen-2 required for normal regeneration of the epithelial basement membrane. Haze persists until late repair of the defective epithelial basement membrane. CONCLUSIONS: Defective regeneration of the epithelial basement membrane has a critical role in determining whether a cornea heals with late haze after photorefractive keratectomy or with scarring at the flap edge in LASIK. [[ J Refract Surg . 2016;32(2):118–125.]

PURPOSE: To report femtosecond laser-assisted cataract surgeries in patients with Marfan syndrome with mild, moderate, and severe lens subluxation. METHODS: Case reports. RESULTS: Two patients with Marfan syndrome underwent femtosecond laser-assisted cataract surgery (Alcon LenSx Lasers Inc., Aliso Viejo, CA). One patient had a mild lens subluxation in one eye and a moderate lens subluxation in the fellow eye. The other patient had a severe lens subluxation in one eye. In all eyes, the laser was able to perform a circular and free-floating anterior capsulotomy and lens fragmentation. In two of the eyes it was also helpful in decreasing corneal astigmatism by making corneal intrastromal relaxing incisions. There were no postoperative complications. CONCLUSIONS: Femtosecond laser-assisted cataract surgery is an effective approach for cataract surgery in patients with Marfan syndrome with mild, moderate, and even severe lens subluxation, with the benefits of causing minimal further zonular damage and being able to treat corneal astigmatism with relaxing incisions. [[ J Refract Surg. 2015;31(5):338–341.]

PURPOSE: To evaluate the effectiveness and safety of accelerated corneal collagen cross-linking for postoperative LASIK ectasia after 2 years. METHODS: A prospective, single-center case series was performed with patients treated for postoperative LASIK ectasia. All eyes underwent accelerated corneal collagen cross-linking (CCL-Vario Crosslinking; Peschke Meditrade GmbH, Zurich, Switzerland) at 9 mW/cmA prospective, single-center case series was performed with patients treated for postoperative LASIK ectasia. All eyes underwent accelerated corneal collagen cross-linking (CCL-Vario Crosslinking; Peschke Meditrade GmbH, Zurich, Switzerland) at 9 mW/cm 2 for 10 minutes. The main outcome measures were changes in uncorrected distance visual acuity, corrected distance visual acuity, central corneal thickness, corneal topography, and endothelial cell density. These parameters were assessed at baseline and at the 6-month and 1- and 2-year follow-up visit. RESULTS: The study enrolled 40 eyes of 24 patients (15 male and 9 female) with a mean age of 33.8 ± 7.5 years (range: 24 to 52 years) that attained at least 2 years of follow-up. The surgical procedure was uneventful in all cases. All eyes stabilized after treatment without any further signs of progression and no statistically significant changes in the mean uncorrected distance visual acuity (The study enrolled 40 eyes of 24 patients (15 male and 9 female) with a mean age of 33.8 ± 7.5 years (range: 24 to 52 years) that attained at least 2 years of follow-up. The surgical procedure was uneventful in all cases. All eyes stabilized after treatment without any further signs of progression and no statistically significant changes in the mean uncorrected distance visual acuity ( P = .649), corrected distance visual acuity ( P = .616), mean keratometry ( P =.837), steep keratometry ( P = .956), ultrasonic pachymetry ( P = .135), slit-scanning pachymetry ( P = .276), and endothelial cell density ( P = .523). In addition, 72.5% of the patients presented stable or gains of Snellen lines over time. CONCLUSIONS: Accelerated corneal collagen cross-linking seems to be safe and effective in halting postoperative LASIK ectasia progression after 2 years of follow-up. However, a longer follow-up period with a larger cohort is needed to validate these findings. [[ J Refract Surg. 2015;31(6):380–384.]