A comparative analysis of the effectiveness of laser correction with a mechanical and laser microkeratome for myopia

ABSTRACT Purpose: Myopia, or nearsightedness, is one of the most common eye conditions worldwide. However, a comparison of the effectiveness of different laser-assisted interventions is lacking. Thus, we aimed to compare the efficacy and safety of LASIK and IntraLASIK in addressing myopia. Methods: The study was conducted in two ophthalmology clinics in Beijing, China, in 2022. A total of 84 patients (152 eyes) with different degrees of myopia were examined and underwent LASIK (n=46, 80 eyes) or IntraLASIK (n=38, 72 eyes). Keratometry, corneal topography, pachymetry, visual acuity evaluation, and corneal biomechanical analysis were performed before and after the intervention. Results: IntraLASIK produced more precise flaps than LASIK, with deviations of <8 mm and 0.1 mm from the intended thickness and diameter, respectively. LASIK resulted in nonuniform flaps, with thickness deviations of 5-86 mm. IntraLASIK demonstrated a superior efficacy for patients with severe myopia and thin corneas, with a mean spherical equivalent of 0.9 D at 6 months compared to the 1.4 D for LASIK. Approximately 91% and 83% of the patients with mild to moderate and severe myopia, respectively, achieved results within ± 0.49 D from the refractive target with IntraLASIK. Conclusions: Corneal hysteresis and corneal resistance factor decreased with an increase in laser intensity, and they decreased faster with thinner corneas. Thus, IntraLASIK is more useful than LASIK in patients with thin corneas and severe myopia.

Safety of intraoperative autologous plasma incubation of corneal grafts for reducing endothelial cell loss: a pilot study.

Background/aims: Corneal endothelial cell loss contributes to transplant failure. Autologous plasma products (APP) activate salvaging pathways that can prevent oxidative stress perioperatively. This study aimed to evaluate the safety of intraoperative incubation of full-thickness corneal grafts in platelet-rich plasma (aPRP) and plasma rich in growth factors (PRGF-Endoret) in mitigating postoperative corneal endothelial cell loss (ECL). Methods: Pilot study including patients undergoing penetrating keratoplasty (PK) for various indications between June 2021 and December 2022. Patients were randomly assigned to receive either aPRP or PRGF-Endoret incubation, while those who declined intervention served as the control group. Demographic and clinical data were collected, including preoperative and postoperative endothelial cell count, intraocular pressure, pachymetry, and adverse reactions. Results: Thirty individuals who underwent PK completed follow-up: eight from the aPRP group, 10 from the PRGF-Endoret group, and 12 from the control group. No adverse events related to APP treatment were recorded. In the first and third postoperative months, the APP group had significantly lower ECL percentages (37% vs. 25%, p = 0.02, and 44% vs. 33%, p = 0.02, respectively); this trend was maintained in the sixth month. When stratified, the PRGF-Endoret group showed significant differences in ECL reduction compared to controls at both time points (p = 0.03 and p = 0.05, respectively). The aPRP group showed a similar statistically significant outcome exclusively on the third postoperative month (p = 0.04). APP tended to reduce corneal edema faster than controls. Hexagonality was significantly better in the APP groups in the first and third months, particularly in the PRGF-Endoret group (p < 0.005). Conclusion: Preoperative incubation with APP is safe and promotes better endothelial cell quality and quantity in the early postoperative period following PK. These findings suggest a potential clinical benefit in enhancing graft outcomes and warrant further investigation.

Assessment by the Scheimpflug imaging system of corneal clarity and anterior segment properties in rosacea patients

Abstract Objective To evaluate the effects of rosacea on ocular surface changes such as alterations in dry eye parameters, corneal densitometry, and aberrations, in comparison with healthy controls. Methods A total of 88 eyes of 44 patients diagnosed with rosacea and 88 eyes of 44 healthy controls were enrolled in this cross-sectional study. All participants underwent a comprehensive dermatologic and ophthalmic examination and Tear Break-Up Time (TBUT) and Schirmer-1 tests were performed. The rosacea subtype and Demodex count and OSDI scores of all participants were recorded. Corneal topographic, densitometric, and aberrometric measurements were obtained using the Scheimpflug imaging system. Results The mean age of the 44 patients was 41.2 ± 11.0 years of whom 31 (70.5%) were female. The mean TBUT and Schirmer-1 test values were significantly decreased and OSDI scores were significantly increased in the rosacea group compared to healthy controls (p < 0.01 for all). The most common subtype of rosacea was erythematotelangiectatic rosacea (70.4%). The severity grading of rosacea revealed that 18 (40.9%) patients had moderate erythema. The median (min-max) Demodex count was 14.0 (0-120) and the disease duration was 24.0 (5-360) months. The comparison of the corneal densitometry values revealed that the densitometry measurements in all concentric zones, especially in central and posterior zones were higher in rosacea patients. Corneal aberrometric values in the posterior surface were also lower in the rosacea group compared to healthy controls. The topographic anterior chamber values were significantly lower in the rosacea group. Study limitations Relatively small sample size, variable time interval to hospital admission, and lack of follow-up data are among the limitations of the study. Future studies with larger sample sizes may also enlighten the mechanisms of controversial anterior segment findings by evaluating rosacea patients who have uveitis and those who do not. Conclusion Given the fact that ocular signs may precede cutaneous disease, rosacea is frequently underrecognized by ophthalmologists. Therefore, a comprehensive examination of the ocular surface and assessment of the anterior segment is essential. The main priority of the ophthalmologist is to treat meibomian gland dysfunction and Demodex infection to prevent undesired ocular outcomes.

Combined Rotating Ultra-High-Resolution Spectral Domain OCT and Scheimpflug Imaging for In Vivo Corneal Optical Biopsy.

PURPOSE: This article introduces the Pentacam® Cornea OCT (optical coherence tomography). This advanced corneal imaging system combines rotating ultra-high-resolution spectral domain OCT with sub- 2-micron axial resolution and Scheimpflug photography. The purpose of this study is to present the first experience with the instrument and its potential for corneal diagnostics, including optical biopsy. METHODS: In this prospective study, the Pentacam® Cornea OCT was used to image the corneas of seven patients. The novel wide-angle pericentric scan system enables optimal OCT imaging performance for the corneal layer structure over the entire width of the cornea, including the limbal regions. A detailed analysis of the resulting images assessed the synergism between the OCT and Scheimpflug photography. RESULTS: The Pentacam® Cornea OCT demonstrated significantly improved image resolution and ability to individualize corneal layers with high quality. There is a synergism between the OCT high-definition signal to individualize details on the cornea and Scheimpflug photography to detect and quantify corneal scattering. The noncontact exam was proven safe, user-friendly, and effective for enabling optical biopsy. CONCLUSIONS: Pentacam® Cornea OCT is an advancement in corneal imaging technology. The ultra-high-resolution spectral domain OCT and Scheimpflug photography provide unprecedented detail and resolution, enabling optical biopsy and improving the understanding of corneal pathology. Further studies are necessary to compare and analyze the tomographic reconstructions of the cornea with the different wavelengths, which may provide helpful information for diagnosing and managing corneal diseases.

Keratoconus and Corneal Ectasia with Relatively Low Keratometry.

INTRODUCTION: The study aims to demonstrate and estimate the prevalence of clinical corneal ectasia and keratoconus (KC) in patients with relatively low keratometry (low-K KC). METHODS: In a retrospective, analytical, and non-interventionist study, one eye was randomly selected from 1054 patients from the original Tomographic Biomechanical Index (TBIv1) study and the external validation (from Rio de Janeiro, Brazil, and Milan, Italy clinics). Patients were stratified into three groups. Group 1 included 736 normal patients, and groups 2 and 3 included 318 patients with clinical KC in both eyes, divided into low-K KC (90 patients) and high-K KC (228 patients), respectively. All patients underwent a comprehensive ophthalmological evaluation along with Pentacam and Corvis ST (Oculus, Wetzlar, Germany) examinations. Cases with maximum mean zone 3 mm keratometry (Kmax zone mean 3 mm) lower than 47.6 diopters (D) were considered as low-keratometry keratoconus, and cases with Kmax zone mean 3 mm higher than 47.6 D were regarded as high-keratometry keratoconus. RESULTS: Ninety (28.30%) of the 318 KC group presented ectasia with low-keratometric values (low-Kmax). The average age in the normal group was 39.28 years (range 6.99-90.12), in the low-Kmax KC group it was 37.49 (range 13.35-78.45), and in the high-Kmax KC group it was 34.22 years (range 12.7-80.34). Mean and SD values and median (range), respectively, of some corneal tomographic and biomechanical parameters evaluated from the low-Kmax KC group were as follows: Belin-Ambrósio enhanced ectasia display (BAD-D) 3.79 ± 1.62 and 3.66 (0.83-9.73); Pentacam random forest index (PRFI) 0.78 ± 0.25 and 0.91 (0.05-1); corneal biomechanical index (CBI) 0.58 ± 0.43 and 0.75 (0-1); TBI 0.93 ± 0.17 and 1 (0.35-1); and stiffness parameter at A1 (SP-A1) 86.16 ± 19.62 and 86.05 (42.94-141.66). CONCLUSION: Relatively low keratometry, with a Kmax lower than 47.6 D, can occur in up to 28.30% of clinical keratoconus. These cases have a less severe presentation of the disease. Future studies involving larger populations and prospective designs are necessary to confirm the prevalence of keratoconus with low keratometry and define prognostic factors in such cases.

Prevalence and antibiotic resistance in bacterial isolates of dogs with ulcerative keratitis in São Paulo State, Brazil.

OBJECTIVE: Identify microorganisms present in canine eyes affected by ulcerative keratitis and assess its resistance profile to available antimicrobial drugs. METHODS: Samples were collected from 88 canine eyes that exhibited ulcerative keratitis. They were identified using MALDI-TOF and subjected to antimicrobial susceptibility testing by disk diffusion. RESULTS: Among the assessed subjects, brachycephalic dogs accounted for 74.48% (50/83) of the evaluated canines. Among the 88 evaluated eyes, 90.9% (80/88) showed positive cultures, with 11.33% (10/88) of the samples isolating more than one species of bacteria. Of all bacterial isolates identified (90), Gram-positive bacteria accounted for 63.33% (57/90), while Gram-negative bacteria constituted 36.66% (33/90), with predominance of Staphylococcus spp. at 35.55% (32/90) being, Staphylococcus pseudintermedius at 68.75% (22/32), and Pseudomonas aeruginosa at 15.55% (14/90), respectively. Staphylococcus spp. exhibited resistance to penicillin (89.29%), sulfadiazine and trimethoprim (60.71%), and tetracycline (67.86%), while doxycycline (88.89%), cefotaxime (85.71%), chloramphenicol (82.14%), gentamicin, and moxifloxacin (78.57%) showed the highest sensitivity rates. Pseudomonas aeruginosa displayed sensitivity (100%) to gentamicin and imipenem, and resistance (8.33%) to norfloxacin, ciprofloxacin, and cefepime. Similarly, the Enterobacteriaceae family showed higher sensitivity to amikacin and gentamicin (88.89%), imipenem (88.24%), and levofloxacin (87.5%), with pronounced resistance to amoxicillin-clavulanate (50%) and cefazolin (47.06%). This highlights multiresistance in 23.33% (21/90) of the isolates. CONCLUSIONS: The most isolated species in canine ulcerative keratitis are S. pseudintermedius and P. aeruginosa. However, other species were also isolated, demonstrating diversity in ocular microbiota infection. There is a high-rate multidrug resistance associated with canine ulcerative keratitis. Nevertheless, these strains exhibited sensitivity to antimicrobials commonly used in veterinary ophthalmology.

Determination of progressive endothelial cell loss after posterior chamber phakic intraocular lens implantation.

Comments about endothelial cell loss after posterior chamber phakic intraocular lens are provided, with a particular emphasis on the importance of determining progressive postoperative cell density reduction, excluding that related to surgical trauma.

Mimicking the Physicochemical Properties of the Cornea: A Low-Cost Approximation Using Highly Available Biopolymers.

Corneal diseases represent a significant global health challenge, often resulting in blindness, for which penetrating keratoplasty is the clinical gold standard. However, in cases involving compromised ocular surfaces or graft failure, osteo-odonto keratoprosthesis (OOKP) emerges as a vital yet costly and complex alternative. Thus, there is an urgent need to introduce soft biomaterials that mimic the corneal tissue, considering its translation's physicochemical, biological, and economic costs. This study introduces a cross-linked mixture of economically viable biomaterials, including gelatin, chitosan, and poly-D-lysine, that mimic corneal properties. The physicochemical evaluation of certain mixtures, specifically gelatin, chitosan, and poly-D-lysine cross-linked with 0.10% glutaraldehyde, demonstrates that properties such as swelling, optical transmittance, and thermal degradation are comparable to those of native corneas. Additionally, constructs fabricated with poly-D-lysine exhibit good cytocompatibility with fibroblasts at 72 h. These findings suggest that low-cost biopolymers, particularly those incorporating poly-D-lysine, mimic specific corneal characteristics and have the potential to foster fibroblast survival. While further studies are required to reach a final corneal-mimicking solution, this study contributes to positioning low-cost reagents as possible alternatives to develop biomaterials with physicochemical properties like those of the human cornea.

Assessment by the Scheimpflug imaging system of corneal clarity and anterior segment properties in rosacea patients.

OBJECTIVE: To evaluate the effects of rosacea on ocular surface changes such as alterations in dry eye parameters, corneal densitometry, and aberrations, in comparison with healthy controls. METHODS: A total of 88 eyes of 44 patients diagnosed with rosacea and 88 eyes of 44 healthy controls were enrolled in this cross-sectional study. All participants underwent a comprehensive dermatologic and ophthalmic examination and Tear Break-Up Time (TBUT) and Schirmer-1 tests were performed. The rosacea subtype and Demodex count and OSDI scores of all participants were recorded. Corneal topographic, densitometric, and aberrometric measurements were obtained using the Scheimpflug imaging system. RESULTS: The mean age of the 44 patients was 41.2 ±â€¯11.0 years of whom 31 (70.5%) were female. The mean TBUT and Schirmer-1 test values were significantly decreased and OSDI scores were significantly increased in the rosacea group compared to healthy controls (p < 0.01 for all). The most common subtype of rosacea was erythematotelangiectatic rosacea (70.4%). The severity grading of rosacea revealed that 18 (40.9%) patients had moderate erythema. The median (min-max) Demodex count was 14.0 (0-120) and the disease duration was 24.0 (5-360) months. The comparison of the corneal densitometry values revealed that the densitometry measurements in all concentric zones, especially in central and posterior zones were higher in rosacea patients. Corneal aberrometric values in the posterior surface were also lower in the rosacea group compared to healthy controls. The topographic anterior chamber values were significantly lower in the rosacea group. STUDY LIMITATIONS: Relatively small sample size, variable time interval to hospital admission, and lack of follow-up data are among the limitations of the study. Future studies with larger sample sizes may also enlighten the mechanisms of controversial anterior segment findings by evaluating rosacea patients who have uveitis and those who do not. CONCLUSION: Given the fact that ocular signs may precede cutaneous disease, rosacea is frequently underrecognized by ophthalmologists. Therefore, a comprehensive examination of the ocular surface and assessment of the anterior segment is essential. The main priority of the ophthalmologist is to treat meibomian gland dysfunction and Demodex infection to prevent undesired ocular outcomes.

Exploring clinical variability in gelsolin amyloidosis: Brazilian family case study with confocal microscopy.

INTRODUCTION: Genetic mutations or inflammatory, degenerative, or neoplastic conditions can trigger amyloidosis. Hereditary gelsolin amyloidosis is a genetic disorder primarily marked by amyloid fibrils composed of misfolded gelsolin fragments. CASE REPORT: We present three sisters with AGel amyloidosis, illustrating its clinical diversity. Patient 1, a 51-year-old, had bilateral ptosis, ocular discomfort, and dry eye syndrome due to cranial nerve involvement. Patient 2, a 53-year-old, experienced progressive bilateral visual impairment. Patient 3, a 50-year-old, exhibited right eye ectropion. Genetic analysis, with the identical mutation, heterozygous c.640G > A (p.Asp214Asn) mutation, confirmed AGel amyloidosis diagnoses, with common findings including lattice corneal amyloidosis, reduced corneal sensitivity, and recurrent corneal erosions. Neurological manifestations included ataxia and peripheral neuropathy, with skin abnormalities observed in patient 1. Ocular involvement severity and distribution varied among patients. DISCUSSION: Common ocular and neurological manifestations validated AGel amyloidosis diagnoses, reinforcing its hereditary basis. Neurological symptoms highlighted the disorder's impact on various organ systems, while skin abnormalities contributed to ocular discomfort. Variable ocular involvement emphasized the disorder's heterogeneity. These patients emphasize hereditary gelsolin amyloidosis's clinical diversity and suggest potential environmental influences on disease expression. Genetic confirmation and confocal microscopy findings reaffirm the genetic basis while raising questions about assessing systemic disease severity, necessitating further investigation in larger cohorts. Ophthalmologists' specialized care is crucial for managing ocular symptoms, given the absence of a universal cure.

Aspectos a considerar para el diagnóstico del queratocono infantil / Aspects to consider for the diagnosis of infant keratoconus

Introducción: Globalmente, existe un aumento de la prevalencia del queratocono y su diagnóstico en edades tempranas. Se notifican un gran número de casos subclínicos y otros con una rápida progresión, condicionada por el inicio precoz de la enfermedad y la asociación a factores de riesgo. Objetivo: Describir los aspectos epidemiológicos, clínicos y el resultado de los medios de diagnóstico implicados en la detección precoz del queratocono infantil. Desarrollo: En niños con ametropía hay elementos que alertan la presencia de un queratocono como causa del defecto refractivo. Desde el punto de vista epidemiológico se encuentran: distribución geográfica, rol de la herencia y factores ambientales. Clínicamente se señalan los antecedentes de enfermedades, tales como las alergias, la presencia de miopía o astigmatismo miópico con inestabilidad refractiva y los signos clínicos relacionados con la progresión del cono. En los pacientes de riesgo es preciso realizar exámenes mediante diferentes medios de diagnóstico según su disponibilidad, siendo primordial el análisis refractivo, queratométrico y topográfico. Conclusiones: En la evaluación de los niños con ametropía se deben tener en cuenta elementos epidemiológicos y clínicos que permiten sospechar y diagnosticar precozmente el queratocono. En la interpretación de los resultados de los medios de diagnóstico involucrados en su detección, se deben considerar los hallazgos más frecuentes en la población infantil según el grado de progresión de la ectasia.

Introduction: Globally, there is an increase of the keratoconus prevalence and its diagnosis in early ages. A great number of subclinical cases and others with a quick progression are notified, conditioned by the early onset of the disease and the association with risk factors. Objective: To describe the epidemiological, clinical aspects and the result of diagnostic means involved in the early detection of infant keratoconus. Development: There are elements that alert the presence of a keratoconus as a cause of the refractive defect in children with ametropia. From the epidemiologic point of view they are: geographical distribution, heredity role and environmental factors. History of previous diseases are clinically pointed out, such as allergies, myopia or myopic astigmatism with refractive instability and the clinical signs related to cone progression. In risk patients it is necessary to carry out exams by means of different diagnostic means according to their availability, being essential the refractive, keratometric and topographic analysis. Conclusions: In the evaluation of children with ametropia, epidemiological and clinical elements should be taken into account that allow to suspect and early diagnose the keratoconus. In the interpretation of results of the diagnostic means involved in their detection the most frequent findings in the infant population, should be considered according to the ectasia degree of progression.

El trasplante de córnea en Villa Clara: diez años transcurridos de la primera intervención quirúrgica / Corneal transplantation in Villa Clara: after ten years the first surgical intervention

Introducción: La córnea constituye el elemento más importante del sistema óptico, al ser el primer medio transparente del ojo; tiene la finalidad de mejorar la calidad de la imagen que se forma en la retina, por lo que su transparencia es imprescindible para poder obtener una buena agudeza visual. Cuando sus capas están afectadas por diferentes enfermedades, se requiere sustituir este tejido dañado; este procedimiento, denominado trasplante de córnea o queratoplastia, tiene diferentes finalidades. Objetivo: Caracterizar los resultados de la cirugía de trasplante de córnea tras diez años del primer procedimiento quirúrgico en la provincia de Villa Clara. Métodos: Se realizó un estudio observacional descriptivo longitudinal retrospectivo, con una muestra de 204 pacientes operados de trasplante de córnea en el Hospital Universitario Clínico-Quirúrgico «Arnaldo Milián Castro» de Villa Clara, en el período comprendido entre 2008 y 2018. Las variables estudiadas fueron: sexo, finalidad del procedimiento, diagnóstico y complicaciones. Resultados: Predominó el sexo masculino (53,4 %); la finalidad más frecuente del trasplante tuvo fines ópticos (85,8 %); principal diagnóstico: la queratopatía bullosa (42,7 %); dentro de las complicaciones más frecuentes estuvieron: el rechazo al injerto, el defecto epitelial y el glaucoma secundario. Conclusiones: La cirugía de trasplante de córnea en la provincia de Villa Clara significa un gran avance en el desarrollo y perfeccionamiento para el tratamiento de múltiples afecciones corneales. Los diagnósticos más frecuentes fueron: la queratopatía bullosa y las opacidades corneales; las complicaciones más frecuentes, el rechazo al injerto, la aparición de defectos epiteliales y el glaucoma secundario.

Introduction: the cornea constitutes the most important element of the optical system, being the first transparent medium of the eye; its purpose is to improve the quality of the image that is formed on the retina, so its transparency is essential to obtain good visual acuity. When its layers are affected by different diseases, it is required to replace this damaged tissue; this procedure called cornea transplant or keratoplasty has different purposes. Objective: to characterize the results of corneal transplant surgery ten years after the first surgical procedure in Villa Clara province. Methods: a retrospective, longitudinal, descriptive and observational study was carried out with a sample of 204 patients who underwent corneal transplant surgery at "Arnaldo Milián Castro" Clinical and Surgical University Hospital in Villa Clara between 2008 and 2018. Age, purpose of the procedure, diagnosis and complications were the variables studied. Results: male gender predominated (53.4%); the most frequent purpose of the transplant was for optical purposes (85.8%); bullous keratopathy (42.7%) was the main diagnosis as well as, graft rejection, epithelial defect and secondary glaucoma were among the most frequent complications. Conclusions: corneal transplant surgery in Villa Clara province means a great advance in the development and improvement for the treatment of multiple corneal conditions. The most frequent diagnoses were bullous keratopathy and corneal opacities; graft rejection, the appearance of epithelial defects and secondary glaucoma were the most frequent complications.

Biometric and corneal characteristics in marfan syndrome with ectopia lentis.

PURPOSE: To describe the biometric and corneal characteristics of patients with Marfan Syndrome (MFS) and ectopia lentis. STUDY DESIGN: Observational, descriptive, prospective study. Subjects Individuals with MFS with ectopia lentis (EL). METHODS: Fourty-four eyes of 23 patients underwent Scheimpflug analysis using the Pentacam (Oculus, Wetzlar, Germany), axial length (AL) using the IOL master 700 (Carl Zeiss AG, Oberkochen, Germany), endothelial cell count (ECC) using the CEM-350 (NIDEK, Maihama, Japan) and corneal biomechanics evaluation with the Ocular Response Analyzer: ORA (Reichert Ophthalmic Instruments, Buffalo, New York, USA) and Corvis (Oculus, Wetzlar, Germany). Statistical analysis was performed using IBM SPSS Statistics 25.0. RESULTS: The direction of lens subluxation was most frequently supero-nasal 40.9% (18/44). Mean keratometry (Km) was 40.22±1.76 Diopters (D); mean corneal astigmatism was 1.68±0.83 D; total corneal aberrometric root mean square (RMS) was 2.237±0.795µm; higher-order aberrations (HOAs) RMS were 0.576±0.272µm; mean AL was 25.63±3.65mm; mean ECC was 3315±459cell/mm2; mean CBI was 0.13±0.24, mean TBI was 0.31±0.25, mean posterior elevation was 4.3±4.5µm; mean total corneal densitometry was 16.0±2.14 grayscale units (GSU). CONCLUSION: Increased axial length, flatter and thicker corneas with higher regular astigmatism, normal densitometry, normal corneal biomechanical indices and normal posterior elevation were observed in Marfan patients with EL.

Radial keratotomy: background and how to manage these patients nowadays.

In this review, we presented the principles of radial keratotomy (RK), its evolution, enhancement, and complications, and strategies to manage the consequences of RK in the present day. It is essential to understand the RK procedure f, the theoretical background that supported this surgery, the current effect on the cornea, and how to approach patients needing vision improvement. These patients are developing cataracts that need to be handled well, from the IOL calculation to the surgical procedure. Guided keratorefractive surgery is the most accurate procedure to improve these patient's vision and life. Nevertheless, some patients may need other approaches, such as sutures, penetrating keratoplasty, corneal rings, and pinhole implants, depending on the degree of irregularity of the cornea, ablation depth for guided surgery or if the sutures are open.

Evaluation of biophysical alterations in the epithelial and endothelial layer of patients with Bullous Keratopathy.

The cornea is a fundamental ocular tissue for the sense of sight. Thanks to it, the refraction of two-thirds of light manages to participate in the visual process and protect against mechanical damage. Because it is transparent, avascular, and innervated, the cornea comprises five main layers: Epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. Each layer plays a key role in the functionality and maintenance of ocular tissue, providing unique ultrastructural and biomechanical properties. Bullous Keratopathy (BK) is an endothelial dysfunction that leads to corneal edema, loss of visual acuity, epithelial blisters, and severe pain, among other symptoms. The corneal layers are subject to changes in their biophysical properties promoted by Keratopathy. In this context, the Atomic Force Microscopy (AFM) technique in air was used to investigate the anterior epithelial surface and the posterior endothelial surface, healthy and with BK, using a triangular silicone tip with a nominal spring constant of 0.4 N/m. Six human corneas (n = 6) samples were used for each analyzed group. Roughness data, calculated by third-order polynomial adjustment, adhesion, and Young's modulus, were obtained to serve as a comparison and identification of morphological and biomechanical changes possibly associated with the pathology, such as craters and in the epithelial layer and exposure of a fibrotic layer due to loss of the endothelial cell wall. Endothelial cell membrane area and volume data were calculated, obtaining a relevant comparison between the control and patient. Such results may provide new data on the physical properties of the ocular tissue to understand the physiology of the cornea when it has pathology.

Evaluation of the common pauraque (Nyctidromus albicollis) cornea using light and scanning electron microscopy.

The common pauraque Nyctidromus albicollis (Gmelin, 1789) is a widespread avian species; however due to its nocturnal habits and reclusive behaviour, little is known about their vision and ecology. Most avian species are visually dependent with advanced visual systems providing high spatial resolution, on the species needs. Each ocular structure has a specific role in contributing towards high visual function, and the cornea is the first refractive structure in the visual process. However, the common pauraque cornea had not been described until the present data. Therefore, this study aims to describe the morphology and morphometry of the common pauraque cornea by means of light and scanning electron microscopy to evaluate the cross-sectional anatomy as well as the ultrastructure of the endothelial cells. Histological similarities with the cornea of other birds have been observed, but the thickness of the common pauraque cornea is much smaller than the other described corneas. A better understanding of the common pauraque cornea can help us better explain the physiology of vision and the visual requirements of this species. In turn, this will help us better understand how this species successfully interacts with its environment, and will improve our knowledge on how to interpret pathological changes in their cornea in a clinical setting.

Results of intrastromal corneal ring implantation in advanced keratoconus With the aim of postpoing or avoiding corneal transplantation.

PURPOSE: To evaluate the safety and efficacy of the surgery of intracorneal ring segment implantation with 320° of arc (320-ICRS) in patients with advanced keratoconus stage IV and maximum keratometry (Kmax) above 60 D. METHODS: A prospective, interventional case series study evaluating 25 eyes of 19 patients with keratoconus stage IV and Kmax > 60D in which 320-ICRS were implanted using VisuMax® femtosecond. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), keratometric values (mean - mean-K, flat - K1, and steep - K2), maximum keratometry (Kmax), tomographic astigmatism, refractive astigmatism and asphericity (Q) were assessed preoperatively and at 3, 6 and 12 months after the procedure. RESULTS: The UDVA improved from 1.03 ± 0.28 LogMAR (20/200) to 0.54 ± 0.21 LogMAR (20/60), (p < 0.001), the CDVA (with glasses) improved from 0.63 ± 0.29 LogMAR (20/80) to 0.31 ± 0.16 LogMAR (20/40),(p = 0.004), K1 reduced from 54.41 ± 4.46 D to 49.36 ± 4.11 D (p < 0.001), K2 reduced from 61.15 ± 4.37 D to 53.715 ± 4.05 D, (p < 0.001), mean-K reduced from 57.55 ± 4,17 D to 51.44 ± 3,94 D (p < 0.001), Kmax reduced from 69.80 ± 8.20 D to 63.43 ± 6.31 D (p < 0.001) and asphericity (Q) changed from -1.57 ± 0.35 to -0.77 ± 0.56 (p < 0.001). A total of 89.9% patients reached BCVA wearing scleral contact lens  0.2 LogMAR(20/25). CONCLUSION: 320-ICRS to treat advanced keratoconus appears to be an efficacious and safe procedure, being a surgical alternative to delay or even prevent corneal transplantation.

Bilateral acute iris transillumination (BAIT) syndrome: Differential diagnosis based on clinical, OCT and UBM findings.

INTRODUCTION: Bilateral acute iris transillumination (BAIT) is a relatively new syndrome whose etiopathogenesis is still not fully understood. It is characterized by acute bilateral onset of intense pigment dispersion in the anterior chamber, iris depigmentation with severe transillumination defects, accentuated pigment deposition in the angle, and elevated intraocular pressure (IOP). In literature, the first case was of bilateral acute iris depigmentation (BADI) reported in 2004 in a 77-year-old woman. In 2019, Perone et al. published a review about BAIT syndrome. They reported a total of 79 cases have been published up that date, mainly in Europe and especially in Turkey and Belgium. The majority of reported cases were of bilateral acute iris depigmentation (BADI). BAIT syndrome might be mainly confused with acute iridocyclitis, acute primary angle-closure (APAC) and pigment dispersion syndrome (PDS). In relation to BAIT, controversies still exist regarding the etiology being the differential diagnosis of paramount importance for adequate treatment. PURPOSE: To report a case of BAIT syndrome associated to refractory glaucoma and to discuss the differential diagnosis based on clinical, OCT and UBM findings. METHODS: We present a case of BAIT syndrome in which clinical, OCT and UBM findings have pointed out the similarities and, mainly the diagnosis differences with other ocular diseases. CONCLUSIONS: BAIT syndrome with accentuated IOP rise must be differentiated of other ocular diseases. It requires urgent clinical therapy and/or surgical management as occurred in the present case for avoiding structural damage in OCT and visual field loss. OCT and UBM are critical for early recognition, differential diagnosis and management.

Recusa familiar para doação de córneas para transplante: fatores associados e tendência / Negativa familiar para donación de córneas para trasplante: factores asociados y tendencia / Family refusal to donate a cornea for transplantation: associated factors and trends

Resumo Objetivo Analisar a recusa familiar de doação de córnea para transplante em uma Organização de Procura de Órgãos. Métodos Estudo quantitativo do tipo transversal sobre as recusas de córnea de doadores em situação de morte encefálica. A fonte de dados foi constituída pelos Termos de Autorização de Doação de Órgãos e Tecidos firmados entre janeiro de 2001 a dezembro de 2020 em uma Organização de Procura de Órgãos. Os dados foram coletados, tabulados e analisados de forma descritiva e inferencial. O presente estudo foi aprovado pelo Comitê de Ética em Pesquisa. Resultados Dos 2.447 Termos de Autorização de Doação de Órgãos e Tecidos firmados no período, 620 (25.34%) recusaram a doação de córneas. Com relação à tendência temporal de recusas de doação de córneas, o único período que apresentou significância foi de 2001 a 2009, quando as faixas etárias de zero a 11 anos e 12 a 19 anos demonstraram tendência decrescente, e a faixa etária maior ou igual a 60 anos, mostrou-se crescente. No período total de 2001 a 2020, as faixas etárias dos 20 a 40 anos, 41 a 59 anos e maior ou igual a 60 anos apresentaram, 48%, 59% e 73%, respectivamente, menores chances de recusa da doação de córneas. Conclusão A faixa etária apresentou associação com a recusa, tendo em vista que os indivíduos de maior idade apresentaram maiores índices.

Resumen Objetivo Analizar la negativa familiar de donación de córneas para trasplante en una Organización de Búsqueda de Órganos. Métodos: Estudio cuantitativo tipo transversal sobre la negativa de córnea de donantes en situación de muerte encefálica. La fuente de datos estuvo compuesta por los Términos de Autorización de Donación de Órganos y Tejidos firmados entre enero de 2001 y diciembre de 2020 en una Organización de Búsqueda de Órganos. Se recopilaron los datos, luego se tabularon y se analizaron de forma descriptiva e inferencial. El presente estudio fue aprobado por el Comité de Ética en Investigación. Resultados De los 2447 Términos de Autorización de Donación de Órganos y Tejidos firmados en el período, 620 (25,34 %) negaron la donación de córneas. Con relación a la tendencia temporal de negativas de donación de córneas, el único período que presentó significación fue de 2001 a 2009, cuando los grupos de edad de 0 a 11 años y de 12 a 19 años demostraron una tendencia decreciente, y el grupo de edad mayor o igual a 60 años se mostró creciente. En el período total de 2001 a 2020, los grupos de edad de 20 a 40 años, de 41 a 59 años y mayor o igual a 60 años presentaron un 48 %, un 59 % y un 73 %, respectivamente, menor probabilidad de negativa de donación de córneas. Conclusión El grupo de edad presentó relación con la negativa, considerando que los individuos de mayor edad presentan mayores índices.

Abstract Objective To analyze family refusals to donate a cornea for transplantation in an Organ Procurement Organization. Methods This was a quantitative cross-sectional study on corneal donation refusals from potential brain-dead donors. The data source was based on the Terms of Authorization for Donation of Organs and Tissues signed from January 2001 to December 2020 in an Organ Procurement Organization. Data were collected, tabulated, and analyzed in a descriptive and inferential manner. The present study was approved by the Research Ethics Committee. Results Of the 2,447 Terms of Authorization for Donation of Organs and Tissues signed in the above period, 620 (25.34%) of them refused to donate a cornea. Regarding the time trend of corneal donation refusals, the period 2001-2009 was the only one that showed significance, when the 0-11 and 12-19 age groups showed a decreasing trend and that of 60 years or older showed an increasing trend. In the period 2001-2020, the age groups of 20-40, 41-59, and 60 years or older had lower rates of refusal to donate a cornea (48%, 59%, and 73%, respectively). Conclusion The age group is associated with refusal because older individuals had the highest refusal rates.

The association of pre-photorefractive keratectomy Schirmer-1 test value with postoperative corneal epithelial thickness, ocular surface discomfort, and visual acuity

ABSTRACT Purpose: To investigate the association of pre--photorefractive keratectomy Schirmer-1 test value with post--photorefractive keratectomy central corneal epithelial thickness, ocular surface disease index score, and uncorrected distance visual acuity. Methods: Patients were categorized according to preoperative Schirmer-1 value: the normal Schirmer Group (n=54; Schirmer-1 test value, >10 mm) and the low Schirmer Group (n=52; Schirmer-1 test value, between 6 and 10 mm). We analyzed ablation depth, visual acuity, result of Schirmer-1 test (with anesthesia), tear film break-up time, ocular surface disease index score, central corneal epithelial thickness, and spherical equivalent refraction. Results: We found significant differences between the groups in Schirmer-1 test value, tear film break-up time, and ocular surface disease index score, both preoperatively and postoperatively (p<0.001). The preoperative central corneal epithelial thicknesses of the two groups were similar (p>0.05). After photorefractive keratectomy, the Schirmer-1 test value and spherical equivalent refraction decreased in both groups (p<0.05), and ocular surface disease index scores and central corneal epithelial thickness values increased in the low Schirmer Group (p<0.001) but not in the normal Schirmer Group (p>0.05). The postoperative central corneal epithelial thicknesses of the low Schirmer Group were significantly higher than those of the normal Schirmer Group (p<0.001). Postoperative uncorrected distance visual acuity did not differ significantly between the two groups (p>0.05). Conclusions: In patients with low Schirmer-1 test values before photorefractive keratectomy, the corneal epithelium thickened and ocular surface complaints increased during the postoperative period. However, changes in the corneal epithelium did not affect the postoperative uncorrected distance visual acuity. To reduce postoperative problems on the ocular surface in these patients, we recommend that dry eye be treated before photorefractive keratectomy.