Infectious keratitis associated with contact lens wear: REGINFECOR multicenter study.

This 32-centre multicentre study addresses the lack of knowledge about the prevalence and significance of microbial keratitis (MK) associated with contact lens (CL) wear in Spain. A total of 304 cases recruited from 32 hospitals were studied and showed that infectious keratitis associated with contact lens wear mainly affects young women during the summer months. In this study, soft lenses with monthly replacement and single solution cleaning were most commonly used, purchased and fitted in opticians' shops. Common risk factors were identified among users, such as topping off solutions, prolonging the life of lenses, and frequently sleeping, swimming and showering with lenses. Overnight lens wear was significantly associated with a higher incidence of corneal opacities, and the presence of Pseudomonas aeruginosa in bacterial cultures was associated with more severe sequelae and a greater need for corneal transplantation. Although most cases were benign, the time taken to heal was long, which poses a problem for working patients. This study provides valuable epidemiological, microbiological and risk factor information and estimates the incidence of CL related MK in Spain to be approximately 1 case per 30,000 inhabitants per year.

Piggyback corneal como alternativa en el tratamiento del queratocono

El queratocono es una afección inflamatoria, es una ectasia corneal que se caracteriza por un aumento de la curvatura corneal. Se describe como una enfermedad progresiva y asimétrica asociada con cambios estructurales en la organización del colágeno corneal. Existen diferentes opciones terapéuticas con el objetivo de estabilizar la superficie corneal, mejorar la visión y evitar su progresión. El sistema piggyback consiste en adaptar un lente rígido de gas permeable con alta permeabilidad al oxígeno sobre un lente de contacto hidrofílico, es ideal para pacientes que requieren la óptica de un lente de contacto rígido, pero tienen dificultades con su material. Se indica cuando existe una intolerancia a los lentes rígidos de gas permeable, en córneas irregulares y con curvaturas avanzadas. Se presenta una paciente de 24 años de edad con diagnóstico de queratocono desde los 10 años de edad que se corregía con lente rígido de gas permeable. Acudió a consulta del servicio de córnea del Instituto Cubano de Oftalmología Ramón Pando Ferrer, en el año 2010 porque comenzó a presentar intolerancia a los lentes. Debido a que la paciente no presentaba criterio quirúrgico y tenía una agudeza visual mejor corregida con lentes de 1,0 en ambos ojos, se decidió realizar el tratamiento con piggyback corneal. Pese al seguimiento, como parte de la progresión de la enfermedad, a los 10 años de mantenerse con el piggyback, presentó un hidrops corneal agudo, el cual fue tratado. En la actualidad la paciente mantiene seguimiento anual por consulta, sin progresión del queratocono y sin complicaciones con el tratamiento de piggyback corneal.

Keratoconus is an inflammatory condition, a corneal ectasia characterized by increased corneal curvature. It is described as a progressive and asymmetric disease associated with structural changes in the organization of corneal collagen. There are different therapeutic options to stabilize the corneal surface, improve vision and prevent progression. The piggyback system consists of fitting a rigid gas permeable lens with high oxygen permeability over a hydrophilic contact lens, it is ideal for patients who require the optics of a rigid contact lens, but have difficulties with its material. It is indicated when there is intolerance to rigid gas permeable lenses, in irregular corneas and with advanced curvatures. We present a 24-year-old female patient with a diagnosis of keratoconus since she was 10 years old, which was corrected with a rigid gas permeable lens. She went to the cornea service of the Cuban Institute of Ophthalmology Ramón Pando Ferrer, in 2010 because she began to present intolerance to lenses. Since the patient did not present surgical criteria and had a visual acuity better corrected with 1.0 lenses in both eyes, it was decided to perform corneal piggyback treatment. Despite the follow-up, as part of the progression of the disease, after 10 years of piggyback, she presented an acute corneal hydrops, which was treated. At present, the patient maintains annual follow-up via consultation, without progression of keratoconus and without complications with the corneal piggyback treatment.

Lentes de contacto y disbiosis ocular, de lo transitorio a lo patológico / Contact lenses and ocular dysbiosis, from the transitory to the pathological

La microbiota ocular normal está compuesta por diferentes comunidades bacterianas Gram negativas y positivas que actúan en la superficie ocular como comensales. Un desequilibrio en la homeostasis de las especies nativas o disbiosis desencadena alteraciones funcionales que eventualmente pueden conllevar afecciones oculares, señalándose al uso de lentes de contacto como el factor predisponente más relevante. Mediante una revisión bibliográfica que incluyó artículos científicos publicados entre el año 2018 y 2022, se analizó la relación entre la microbiota ocular sana, la disbiosis asociada al uso de lentes de contacto que desencadena afecciones oculares. La microbiota ocular en individuos sanos, se compone principalmente por bacterias de los filos: proteobacterias, actinobacteria y firmicutes. Estas comunidades bacterianas al verse asociadas al uso de lentes de contacto desarrollaron disbiosis, observándose un aumento de ciertos géneros como Staphylococcus spp. y Pseudomonas spp., que en condiciones normales son comensales de la superficie ocular, pero al estar aumentada su abundancia condicionan la aparición de diversas afecciones oculares como eventos infiltrativos corneales, queratitis y úlcera corneal bacterianas. Dichas patologías tienden a evolucionar de manera rápida, lo que, sumado a una detección y tratamiento tardíos, puede determinar un pronóstico visual deficiente. Se sugiere que, frente a diversas afecciones de la superficie ocular, los profesionales en el área de oftalmología conozcan la composición de las comunidades de microorganismos que conforman esta microbiota ocular, de manera de distinguir e identificar correctamente el agente causal y, con ello, brindar un tratamiento adecuado y efectivo al usuario (AU)

Normal ocular microbiota is composed of different Gram-negative and positive bacterial communities that act as commensals on the ocular surface. An imbalance in the homeostasis of the native species or dysbiosis triggers functional alterations that can eventually lead to ocular conditions, indicating the use of contact lenses as the most relevant predisposing factor. Through a bibliographic review that added scientific articles published between 2018 and 2022, the relationship between healthy ocular microbiota and dysbiosis associated with the use of contact lenses that trigger ocular conditions was analyzed. The ocular microbiota in healthy individuals is mainly composed of bacteria from the phyla: proteobacteria, actinobacteria and firmicutes. These bacterial communities associated with the use of contact lenses develop dysbiosis, observing an increase in certain genera such as Staphylococcus spp. and Pseudomonas spp., which under normal conditions are commensals of the ocular surface, but as their abundance is increased, they condition the appearance of various ocular conditions such as corneal infiltrative events, bacterial keratitis and corneal ulcer. These pathologies tend to evolve rapidly, which, added to late detection and treatment, can lead to a poor visual prognosis. It is suggested that professionals in the ophthalmology area learn about the composition of the communities of microorganisms that make up this ocular microbiota, in order to correctly distinguish and identify the causative agent, thereby providing a adequate and effective treatment to the user (AU)

Contact lenses and ocular dysbiosis, from the transitory to the pathological.

Normal ocular microbiota is composed of different Gram-negative and positive bacterial communities that act as commensals on the ocular surface. An imbalance in the homeostasis of the native species or dysbiosis triggers functional alterations that can eventually lead to ocular conditions, indicating the use of contact lenses as the most relevant predisposing factor. Through a bibliographic review that added scientific articles published between 2018 and 2022, the relationship between healthy ocular microbiota and dysbiosis associated with the use of contact lenses that trigger ocular conditions was analyzed. The ocular microbiota in healthy individuals is mainly composed of bacteria from the phyla: Proteobacteria, Actinobacteria and Firmicutes. These bacterial communities associated with the use of contact lenses develop dysbiosis, observing an increase in certain genera such as Staphylococcus spp. and Pseudomonas spp., which under normal conditions are commensals of the ocular surface, but as their abundance is increased, they condition the appearance of various ocular conditions such as corneal infiltrative events, bacterial keratitis and corneal ulcer. These pathologies tend to evolve rapidly, which, added to late detection and treatment, can lead to a poor visual prognosis. It is suggested that professionals in the ophthalmology area learn about the composition of the communities of microorganisms that make up this ocular microbiota, in order to correctly distinguish and identify the causative agent, thereby providing a adequate and effective treatment to the user.

El efecto del uso prolongado y nocturno de las lentes de contacto en la córnea. A propósito de un caso de descompensación corneal y descenso del recuento endotelial / The effect of prolonged and nocturnal use of contact lenses on the cornea: About a case of corneal decompensation and decreased endothelial count

El edema corneal y la disminución del recuento de células endoteliales son complicaciones relacionadas con la hipoxia crónica de bajo grado, que experimentan los usuarios de lentes de contacto, principalmente debido al uso prolongado y nocturno. Este caso muestra el ejemplo de un paciente que presenta problemas de visión borrosa en ambos ojos, y a quien se le realizó un examen oftalmológico completo que incluyó fotografías, topografía corneal y conteo de células endoteliales. Posteriormente se revisa el metabolismo corneal, la etiopatogenia y las complicaciones derivadas del uso de lentes de contacto (AU)

Corneal edema and decreased endothelial cell count are complications related to chronic low-grade hypoxia experienced by contact lens wearers, primarily due to prolonged and overnight wear. This case shows the example of a patient who has blurred vision problems in both eyes and who underwent a complete ophthalmologic examination that included photographs, corneal topography and endothelial cell count. Subsequently, the corneal metabolism, the etiopathogenesis and the complications derived from the use of contact lenses are reviewed (AU)

The effect of prolonged and nocturnal use of contact lenses on the cornea: about a case of corneal decompensation and decreased endothelial count.

Corneal edema and decreased endothelial cell count are complications related to chronic low-grade hypoxia experienced by contact lens wearers, primarily due to prolonged and overnight wear. This case shows the example of a patient who has blurred vision problems in both eyes and who underwent a complete ophthalmologic examination that included photographs, corneal topography and endothelial cell count. Subsequently, the corneal metabolism, the etiopathogenesis and the complications derived from the use of contact lenses are reviewed.

Lentes de contacto dentales: una alternativa de tratamiento estético

RESUMEN El presente reporte tuvo como objetivo presentar la planificación y ejecución de un tratamiento rehabilitador con el empleo de la técnica de lentes de contacto dentales para la resolución estética de la forma y tamaño de las piezas dentales. Se reportó el caso de un paciente de sexo masculino de 20 años de edad que presentaba inconformidad con su sonrisa por la presencia de diastema en los incisivos centrales de la arcada superior; por lo que se efectuó un tratamiento estético con el empleo de lentes de contacto dentales de disilicato de litio, en el cual se realizó un desgaste mínimo de la superficie dental para garantizar una correcta inserción y adaptación de los laminados de cerámica. Al año del seguimiento no se detectaron infiltraciones, sensibilidades o fracturas en los dientes rehabilitados con esta técnica. Entre las ventajas de lentes de contacto dentales o lumineers, como también es conocida, presenta una máxima conservación de la estructura dental, además, de altos niveles de estética por su gran translucidez y brillo similar a la de los dientes naturales.

ABSTRACT The objective of this report was to present the planning and execution of a rehabilitative treatment with the use of the dental contact lens technique for the aesthetic resolution of the shape and size of the teeth. The case is a 20-year-old male patient who presented dissatisfaction with his smile due to the presence of diastema in the central incisors of the upper arch. An aesthetic treatment was carried out with the use of lithium disilicate dental contact lenses. Minimal wear of the dental surface was implemented, to guarantee a correct insertion and adaptation of the ceramic laminates. After one year of follow-up, no infiltrations, sensitivities or fractures were detected in the teeth rehabilitated with this technique. Among the advantages of dental contact lenses or lumineers, as it is also known, is that it presents a maximum preservation of the dental structure, as well as high levels of aesthetics due to its great translucency and brightness similar to that of natural teeth.

RESUMO O objetivo deste relatório foi apresentar o planejamento e execução de um tratamento reabilitador com a utilização da técnica de lentes de contato odontológicas para a resolução estética da forma e do tamanho dos dentes. Foi relatado o caso de um paciente do sexo masculino, 20 anos, que apresentava insatisfação com o sorriso devido à presença de diastemas em incisivos centrais da arcada superior; Para tanto, foi realizado um tratamento estético com a utilização de lentes de contato odontológicas de dissilicato de lítio, no qual foi realizado um desgaste mínimo da superfície dentária para garantir a correta inserção e adaptação dos laminados cerâmicos. Em um ano de acompanhamento, não foram detectadas infiltrações, sensibilidades ou fraturas nos dentes reabilitados com esta técnica. Dentre as vantagens das lentes de contato ou luminárias odontológicas, como também é conhecido, apresenta uma preservação máxima da estrutura dentária, bem como elevados níveis de estética devido a sua grande translucidez e brilho semelhante ao dos dentes naturais.

A refined model on flow and oxygen consumption in the human cornea depending on the oxygen tension at the interface cornea/post lens tear film during contact lens wear.

The study of oxygen consumption rate under" in vivo" human cornea during contact lens wear has been technically a challenge and several attempts have been made in the last 20 years to model the physiology of the human cornea during contact lens wear. Unfortunately, some of these models, based on a constant corneal oxygen consumption rate, produce areas on the cornea where the oxygen tension is negative, which has no physical sense. In order to avoid such inconsistency, different researchers have developed alternative models of oxygen consumption, which predict the likely oxygen metrics available at the interface cornea/post lens tear film by determination of oxygen flux, oxygen consumption, and oxygen tension through the different layers (endothelium, stroma, and epithelium). Although oxygen deficiency produces corneal edema, corneal swelling, hypoxia, acidosis, and other abnormalities, the estimation of the oxygen distribution below the impact of a contact lens wear is interesting to know which lens transmissibility was adequate to maintain the cornea and avoid epithelial and stromal anoxia. The estimation of minimum transmissibility for a lens for extended wear applications will be very useful for both clinicians and manufacturers. The aim of this work is to present a complete discussion based on Monod kinetics model that permits give an estimation of oxygen partial pressure distribution, the profile distribution of corneal flux and oxygen consumption rate, and finally the estimation of the relaxation mechanism of the cornea depending on the oxygen tension at the interface cornea/post lens tear film. Relaxation time in this context can quantify the capability of the corneal tissue to adapt to increasing concentrations of oxygen. It is proposed this parameter as a biological meaningful indicator of the interaction between contact lens polymers and living tissues such as the corneal cellular layer.

Ultra-Thin Veneers: A Current State-of-the-Art

ABSTRACT: Currently, the aesthetic requirements of patients are increasing and they have begun to request more conservative treatments. One alternative to achieve harmonious results is through the indication of ultra-thin veneers. This is considered a conservative technique but the evidence basis for it seems to be limited. The following review attempts to summarize the relevant literature to establish guidelines for clinicians based on scientific evidence regarding the use of ultra-thin veneers. Ultra-thin veneers seem to be a reliable alternative to achieve aesthetic and harmonious results; however, many factors must be considered to ensure correct diagnosis and treatment plan. In addition, the literature is scarce in relation to a consensus on tooth preparation and long-term studies evaluating the success of this type of treatment over time do not exist.

RESUMEN: Actualmente, los requisitos estéticos de los pacientes han aumentando y solicitan tratamientos más conservadores. Una alternativa para lograr resultados armónicos es mediante la indicación de carillas o laminados ultrafinos. Esta se considera una técnica conservadora, pero la base teórica parece ser limitada. La siguiente revisión intenta resumir la literatura relevante para establecer pautas para clínicas basadas en evidencia científica sobre el uso de carillas ultrafinas. Las carillas ultrafinas parecen ser una alternativa confiable para lograr resultados estéticos y armónicos; sin embargo, se deben considerar muchos factores para asegurar un diagnóstico y plan de tratamiento correcto. Además, la literatura es escasa en relación a un consenso sobre la preparación dental y no existen estudios a largo plazo que evalúen el éxito de este tipo de tratamiento a lo largo del tiempo.

Smart contact lens: A promising therapeutic tool in aniridia.

OBJECTIVE: The perform pre-clinical testing using optical design tools to simulate the optical quality of a smart artificial iris platform encapsulated in a scleral contact lens. These tools allow us to generate aniridia eye models and evaluate different metrics of visual quality and retinal illumination based on the aperture of the artificial iris based on liquid crystals. METHOD: The OCT imaging technique was used to measure the geometry of the anterior segment in a patient with aniridia and, from these data, the eye model was generated with the Zemax optical design program and specific programs developed in Matlab. Ocular aberrations were calculated and the visual function of the anirida eye model was evaluated in three scenarios: (i) without optical correction, (ii) with correction with a commercial scleral contact lens, and (iii) with correction with an optical lens. Intelligent contact based on artificial iris. RESULTS: Optical quality in patients with aniridia is limited by the magnitude of high-order aberrations. Conventional scleral contact lens design accurately corrects for blur but is unable to compensate for high-order ocular aberrations, especially spherical aberrations. The artificial iris-based smart contact lens design enables virtually all high-order aberrations to be compensated with active control of the pupillary diameter (activation of liquid crystal cells based on ambient lighting). In addition to minimizing high-order aberrations, reducing the pupil size would increase the depth of focus. CONCLUSIONS: This article demonstrates by means of optical simulations the concept of an intelligent artificial iris platform encapsulated in a scleral contact lens and its possible application in patients with aniridia. Furthermore, it allows us to anticipate possible visual results in clinical trials with healthy patients (after application of mydriatic agents) and in patients with aniridia. The results demonstrate a better visual quality and a decrease in retinal illumination.

Biocompatibility with the Ocular Surface and Antimicrobial Activity of a New Multi-Purpose Contact Lens Solution / Biocompatibilidad con la superficie ocular y actividad antimicrobiana de una nueva solución multipropósito para lentes de contacto / Biocompatibilidade com a superfície ocular e atividade antimicrobiana de uma nova solução de lentes de contato multipropósito

Abstract Introduction: Multipurpose solutions (MPS) for soft contact lenses (SCL) play an essential role in inhibiting potentially pathogenic agents. Their antimicrobial effectiveness is assessed in vitro and their safety in vivo, with clinical trials that include a combination of different solutions and lens materials. The objective is to assess the biocompatibility of a new SCL MPS produced in Colombia that contains polyhexamethylene biguanide (PHMB) and to determine its antimicrobial activity. Materials and Methods: This was a crossover study with 25 subjects who did not wear lens and who were fitted with different combinations of five SCL materials with either MPS or control physiological saline solution (CS). Corneal thickness, conjunctival hyperemia, corneal staining, and comfort were assessed after two hours of wearing SCL. Antimicrobial effectiveness was measured using ISO 14729 standard assays. Results: When considering SCL material, there was a statistically significant difference between the new MPS and the CS for Comfilcon A (p < 0.05). There was no statistical or clinically significant difference for corneal thickness or corneal staining between the combination of lens material and new MPS with the CS (p > 0.05). After two hours of lens insertion, comfort scores were higher than 7.8. The MPS reduced bacteria colony forming units (CFU) in over 3 log, and fungal CFU in over 1.0 log. Conclusions: The new MPS met the antimicrobial standards of ISO 14729, is considered safe and biocompatible with the ocular surface and retains high comfort levels.

Resumen Introducción: las soluciones multipropósito (SMP) para lentes de contacto blandos (LCB) desempeñan un papel esencial en la inhibición de agentes potencialmente patógenos. Su efectividad antimicrobiana se evalúa in vitro, y su seguridad, in vivo, con ensayos clínicos que incluyen una combinación de diferentes soluciones y materiales para lentes. El objetivo es evaluar la biocompatibilidad de una nueva SMP producida en Colombia que contiene polihexametileno biguanida (PHMB) y determinar su actividad antimicrobiana. Materiales y métodos: estudio cruzado con 25 sujetos no usuarios de lentes, que fueron adaptados con cinco combinaciones diferentes de materiales de LCB con una nueva SMP o solución salina fisiológica de control (CS). El grosor corneal, la hiperemia conjuntival, la tinción corneal y la comodidad se evaluaron después de dos horas de uso del LC. La efectividad antimicrobiana se midió utilizando ensayos estándar ISO 14729. Resultados: considerando el material del LCB, solo hubo una diferencia estadísticamente significativa entre la nueva SMP y el CS para el Comfilcon A (p < 0.05). Tampoco hubo diferencias estadísticamente o clínicamente significativas para el grosor corneal o la tinción corneal, entre la combinación del material del lente y la nueva SMP con el CS (p > 0.05). Después de dos horas de uso del lente, las puntuaciones de confort fueron superiores a 7.8. La SMP redujo las unidades formadoras de colonias (UFC) de bacterias en más de 3 log, y las UFC fúngicas en más de 1.0 log. Conclusiones: la nueva SMP cumplió con los estándares antimicrobianos de ISO 14729, y se considera segura y biocompatible con la superficie ocular, con altos niveles de confort.

Resumo Introdução: as soluções multipropósito (SMP) para lentes de contato macias (LCM) apresentam um papel essencial na inibição de agentes potencialmente patógenos. Sua eficácia como agente antimicrobiano se valia in vitro, e sua segurança, in vivo, como ensaios clínicos que incluem uma combinação de diferentes soluções e materiais para lentes. O objetivo é avaliar a biocompatibilidade de uma nova SMP produzida na Colômbia a base de polihexametileno biguanida (PHMB) e determinar seu potencial antimicrobiano. Materiais e métodos: estudo cruzado com 25 indivíduos não usuários de lentes, que foram adaptados com cinco combinações diferentes de LCM como uma nova SMP ou solução salina fisiológica como controle (CS). A espessura da córnea, a hiperemia conjuntival, a coloração da córnea e a comodidade, foram avaliadas após duas horas de uso da LCB. A eficácia antimicrobiana foi medida com ensaios padrão ISO 14729. Resultados: considerando o material da LCB, houve apenas uma diferença estatisticamente significativa entre a nova SMP e o CS, paro o Comfilcon A (p <0.05). Não houve diferença estatisticamente ou clinicamente significativa para a espessura da córnea ou a coloração da córnea, entre a combinação do material da lente e a nova SMP com o controle CS (p > 0.05). Após duas horas de uso, as pontuações de conforto foram superiores a 7,8. A SMP reduziu as unidades formadoras de colônias (UFC) de bactérias em mais de 3 log, e as UFC fúngicas em mais de 1.0 log. Conclusões: a nova SMP cumpriu com os padrões antimicrobianos ISO 14729, é considerada segura e biocompatível com a superfície ocular, com altos níveis de conforto.

Smart contact lens: a promising therapeutic tool in aniridia. / Lente de contacto inteligente: una prometedora herramienta terapéutica en aniridia.

OBJECTIVE: To perform pre-clinical testing using optical design tools to simulate the optical quality of a smart artificial iris platform encapsulated in a scleral contact lens. These tools allow us to generate aniridia eye models and evaluate different metrics of visual quality and retinal illumination based on the aperture of the artificial iris based on liquid crystals. METHOD: The OCT imaging technique was used to measure the geometry of the anterior segment in a patient with aniridia and, from these data, the eye model was generated with the Zemax optical design program and specific programs developed in Matlab. Ocular aberrations were calculated and the visual function of the anirida eye model was evaluated in three scenarios: (i) without optical correction, (ii) with correction with a commercial scleral contact lens, and (iii) with correction with an optical lens. intelligent contact based on artificial iris. RESULTS: Optical quality in patients with aniridia is limited by the magnitude of high-order aberrations. Conventional scleral contact lens design accurately corrects for blur but is unable to compensate for high-order ocular aberrations, especially spherical aberrations. The artificial iris-based smart contact lens design enables virtually all high-order aberrations to be compensated with active control of the pupillary diameter (activation of liquid crystal cells based on ambient lighting). In addition to minimizing high-order aberrations, reducing the pupil size would increase the depth of focus. CONCLUSIONS: This article demonstrates by means of optical simulations the concept of an intelligent artificial iris platform encapsulated in a scleral contact lens and its possible application in patients with aniridia. Furthermore, it allows us to anticipate possible visual results in clinical trials with healthy patients (after application of mydriatic agents) and in patients with aniridia. The results demonstrate a better visual quality and a decrease in retinal illumination.

The effects of light scatter when using a photochromic vs. non-photochromic contact lens.

PURPOSE: To assess the visual effects of wearing both an activated and an inactivated photochromic contact lens, with a direct comparison to a non-photochromic contact lens worn in the fellow eye. This study focused on the visual effects of scatter quantified as the minimum distance between two points of light, and the diameter of the halo and starbursts that surround a bright white point source. METHODS: 60 subjects (aged 18-65 years) were measured in a contralateral design where lens type was randomly assigned, one type to each eye. During activated testing, all visual measures of both study lenses were made while each eye was illuminated by a violet (λmax=365, half bandwidth 20nm) activator, which caused steady-state activation of the photochromic lens during the period of testing. Two-point thresholds were determined by measuring the minimum distance between two points of broadband xenon light. Glare geometry was measured using an aperture (∼4mm) that created a bright point source of light 45 inches from the plane of the eye. Between the point source and subject, a centering precision caliper was used to measure lateral spread of halos (diffusion around the source) and visual spokes. The head was stabilized using an adjustable head-rest assembly and the eye was aligned and monitored with a bore camera. RESULTS: Compared to the non-photochromic lens, and based on the stimulus conditions used in these measurements, the activated and inactivated photochromic lens reduced the light spread using the two-point threshold technique by 32% and 19% respectively; the diameter of the halos were reduced by 44% and 16% respectively; and the spokes were narrowed by 39% and 20% respectively. Based on 95% confidence interval testing, these effects were all statistically significant (p<0.05). CONCLUSIONS: These results are consistent with previous data showing that soft contact lenses with a photochromic additive can improve many aspects of visual function, consistent with their level or activation. Our past data focused on visual function under bright light conditions (e.g., glare disability, discomfort, photostress recovery and chromatic contrast) with an activated photochromic. In this study, we found differences even in the inactivated state, using less intense stimuli (10cd/m2 at the source). This suggests that the photochromic lens improves the effects of light scatter even at lower luminance.

Detección de Acanthamoeba por reacción en cadena de la polimerasa en tiempo real en líquidos de conservación de lentes de contacto / Detection of Acanthamoeba sp. by real-time polymerase chain reaction in contact lens solutions

RESUMEN Objetivo: Estandarizar una técnica de reacción en cadena de la polimerasa en tiempo real para la detección del parásito e identificar Acanthamoeba en líquidos conservantes de lentes de contacto. Métodos: Se realizó un estudio descriptivo observacional de corte transversal sobre la técnica de reacción en cadena de la polimerasa en tiempo real para la detección de Acanthamoeba, en el Instituto de Investigaciones en Ciencias de la Salud de la ciudad de Asunción, en Paraguay. Se analizaron 110 líquidos conservantes aportados por usuarios sanos de lentes de contacto, mediante reacción en cadena de la polimerasa en tiempo real y cultivo en medio PAGE - SDS. Resultados: Se estandarizó con éxito la técnica de reacción en cadena de la polimerasa en tiempo real con límite de sensibilidad de 1 pg/µL. Se aisló Acanthamoeba a partir de una muestra (1 por ciento) por método de cultivo, mientras que la carga parasitaria en el líquido conservante fue inferior al límite de detección de la reacción en cadena de la polimerasa en tiempo real. El ADN obtenido del cultivo de dicha muestra fue positivo para Acanthamoeba por este método. Conclusión: El sistema estandarizado presenta buena sensibilidad y podrá ser incorporado en los laboratorios que cuentan con acceso a equipos de reacción en cadena de la polimerasa en tiempo real para un diagnóstico rápido y más eficiente en casos de sospechas de queratitis amebiana. Recomendamos el uso combinado de métodos moleculares y cultivo para aumentar la potencia del diagnóstico, sobre todo en muestras donde la carga parasitaria es muy baja(AU)

ABSTRACT Objective: Standardize a real-time polymerase chain reaction technique for detection of the parasite and identify Acanthamoeba in contact lens solutions. Methods: A cross-sectional observational descriptive study was conducted about a real-time polymerase chain reaction technique for detection of Acanthamoeba at the Institute of Health Sciences Research in the city of Asunción, Paraguay. A total 110 solutions were analyzed, which were provided by healthy contact lens users, by real-time polymerase chain reaction and culture in SDS-PAGE medium. Results: Successful standardization was achieved of the real-time polymerase chain reaction technique with a sensitivity limit of 1 pg/µl. Acanthamoeba was isolated from one sample (1 percent) by culture, whereas the parasite load in the contact lens solution was below the detection limit of the real-time polymerase chain reaction technique. The DNA obtained from the culture of that sample was positive for Acanthamoeba by the real-time polymerase chain reaction technique method. Conclusion: The system standardized exhibits good sensitivity and may be incorporated into laboratories with real-time polymerase chain reaction technique equipment for a rapid and more efficient diagnosis of suspected amoebic keratitis. We recommend the combined use of molecular methods and culture to enhance diagnostic power, mainly in samples where the parasite load is very low(AU)

[Complications associated with the use of soft contact lenses]. / Complicaciones asociadas al uso de lentes de contacto blandas.

Soft contact lenses are a good alternative to the use of glasses for the correction of refractive defects. However, improper use can be associated with complications. Incorrect handling, poor hygiene, or over-use of the lenses can lead to poor tolerance, eye inflammation, and even visions sequelae. In this review, the most common and also the most serious are described, including the infectious and non-infectious complications associated with the use of soft contact lenses, including recommendations for their correct use.

Peripheral refraction and spherical aberration profiles with single vision, bifocal and multifocal soft contact lenses.

PURPOSE: To compare the peripheral refraction and spherical aberration profiles along three visual field meridians of 16 commercial single vision (SV), bifocal (BF) and multifocal (MF) test contact lenses with a single vision control. METHOD: Forty-four participants [24.2±2.4 years, SE: -0.50 to -4.50D] were randomly fitted, contra-laterally, with 6 SV's [Air Optix Aqua (control), Acuvue Oasys, Biofinity, Clariti, Night & Day and Proclear], 3 BF's [Acuvue Bifocal low and high add, MiSight] and 8 MF's [Proclear D & N in 1.5 and 2.5D adds; AirOptix, PureVision low & high adds]. Peripheral refraction was performed across horizontal, oblique and vertical meridians, with lenses on eye using the BHVI-EyeMapper. The power vectors M, J0, J45 and the spherical aberration coefficient were analysed. The peripheral refraction and aberration profiles of the test lenses were compared with the profiles of the control lens using curvature and slope coefficients. RESULTS: Compared to the control, a relative peripheral hyperopic shift (M), a less negative J0 curvature coefficient along the horizontal meridian, a less positive J0 curvature coefficient along the vertical meridian, a less negative J45 curvature coefficient along the oblique meridian and a more positive spherical aberration curvature coefficient along most meridians was seen with the Acuvue Bifocal and all center-near multifocal lenses. For the center-distance multifocal lenses the direction of the curvature coefficients of the same refraction and aberration components was opposite to that of the center-near lenses. The greatest differences in the slope coefficients when compared to the control were found for the Acuvue Bifocal lenses and all multifocal contact lenses for the refractive component M and the spherical aberration coefficient along the horizontal visual field meridian, with the Acuvue Bifocal and the center-near multifocal lenses having more positive coefficients and the center-distance lenses having more negative coefficients. CONCLUSION: When worn on eye, different commercially available lens types produce differences in the direction and magnitude of the peripheral refraction and spherical aberration profiles along different visual field meridians. This information may be relevant to refractive development and myopia control.

Physicochemical stability of contact lenses materials for biomedical applications.

PURPOSE: The physicochemical stability, thermal and water plasticizing effect on transport properties of contact lenses (CL) were analyzed to verify its capacity to maintain the original properties after being dehydrated and rehydrated. METHODS: Two daily disposable (nesofilcon A and delefilcon A) and two monthly CL (comfilcon A and lotrafilcon B) were used. Measurements of refractive index (RI), water content (WC), chemical structure and thermal properties were taken: new (N), after dehydration (D) and rehydrated (R). RI and WC were accessed using a digital automated refractometer (CLR-12-70). Chemical structure was evaluated by a Fourier Transformed Infrared Spectroscopy (FTIR-ATR) and Differential Scanning Calorimetry (DSC) with a calorimeter (Mettler Toledo DSC-821). RESULTS: The FTIR spectrum of N, D and R was quite similar for all CL, with higher differences observed in the transmission between 3500-3000cm-1 due to the hydroxyl group (OH). After dehydration and rehydration, there were no significant changes in the chemical structure. RI and WC of the CL rehydrated did not vary significantly from the initial CL (p>0.05) and thermal properties also confirm that the behavior did not change. It was observed that the glass-transition temperature decrease with increased WC. CONCLUSION: No significant alterations were observed in the physicochemical structure of the materials after dehydration and rehydration showing a good stability of their components. The strong water plasticizing effect in the silicone hydrogel lens materials improves flexibility and chain mobility and may should be considered for other biomedical applications.

Advances in diagnostic applications for monitoring intraocular pressure in Glaucoma: A review.

Continuous intraocular pressure (IOP) monitoring for improving glaucoma diagnosis and treatment has remained a challenge for the past 60 years because glaucoma is the second leading cause of irreversible blindness worldwide. Several devices with different measurement principles and recently developed biosensors with semiconductor materials offer exciting properties. However, none of these devices for continuous IOP monitoring have been fully integrated into clinical practice, primarily due to technical problems. This review summarizes state-of-the-art biosensors developed for IOP monitoring by explaining their basic functions and applications, the main technology (pressure transductors, piezoresistive sensors, capacitive sensors, and resonant sensors), measurement approach (noninvasive, minimally invasive or invasive (surgically implantable)), and telemetry characteristics. To provide updated information for clinicians and researchers, we also describe the advantages and limitations of the application of these new sensors to eye care management. Despite significant improvements in IOP biosensor technology, the accuracy of their measurements must be improved to obtain a clear equivalence with actual IOP (measured in units of mmHg) to facilitate their clinical application. In addition, telemetry systems may be simplified to prevent adverse outcomes for patients and to guarantee the safety of stored data.

Endophthalmitis caused by Fusarium: An emerging problem in patients with corneal trauma. A case series.

BACKGROUND: Although fortunately very rare in countries with a temperate climate, certain factors, such as clinical or pharmacological immunosuppression, may cause Fusarium-related fungal infections to become an emerging problem. Moreover, Fusarium is one of the most important etiological agents in exogenous endophthalmitis, which is often favored by the disruption of the epithelial barriers. AIMS: The aim of this series of clinical cases is to identify characteristic clinical findings that may allow an early diagnosis and more efficient management of this ophthalmologic emergency. METHODS: Three cases of endophthalmitis due to Fusarium solani and Fusarium oxysporum, diagnosed in 2009, 2010, and 2014 in patients from two different health regions belonging to the same health system and separated by around 43 miles, are presented. The Fusarium isolates were initially identified microscopically and the species subsequently confirmed by sequencing the elongation factor alpha (EFα) and internal transcribed spacers (ITS). Susceptibility to antifungal agents was determined using the EUCAST broth dilution method. RESULTS: Evolution was poor as two of the three patients progressed to phthisis bulbi despite surgical measures and broad-spectrum antifungal antibiotic therapy. CONCLUSIONS: It is essential to rapidly instigate multidisciplinary measures to combat suspected endophthalmitis due to Fusarium given the poor prognosis of this type of infection.

Extended depth of focus contact lenses vs. two commercial multifocals: Part 2. Visual performance after 1 week of lens wear.

PURPOSE: To compare the visual performance of prototype contact lenses designed via deliberate manipulation of higher-order spherical aberrations to extend-depth-of-focus with two commercial multifocals, after 1 week of lens wear. METHODS: In a prospective, participant-masked, cross-over, randomized, 1-week dispensing clinical-trial, 43 presbyopes [age: 42-63 years] each wore AIROPTIX Aqua multifocal (AOMF), ACUVUE OASYS for presbyopia (AOP) and extended-depth-of-focus prototypes (EDOF) appropriate to their add requirements. Measurements comprised high-contrast-visual-acuity (HCVA) at 6m, 70cm, 50cm and 40cm; low-contrast-visual-acuity (LCVA) and contrast-sensitivity (CS) at 6m and stereopsis at 40cm. A self-administered questionnaire on a numeric-rating-scale (1-10) assessed subjective visual performance comprising clarity-of-vision and lack-of-ghosting at various distances during day/night-viewing conditions and overall-vision-satisfaction. RESULTS: EDOF was significantly better than AOMF and AOP for HCVA averaged across distances (p≤0.038); significantly worse than AOMF for LCVA (p=0.021) and significantly worse than AOMF for CS in medium and high add-groups (p=0.006). None of these differences were clinically significant (≤2 letters). EDOF was significantly better than AOMF and AOP for mean stereoacuity (36 and 13 seconds-of-arc, respectively: p≤0.05). For clarity-of-vision, EDOF was significantly better than AOP at all distances and AOMF at intermediate and near (p≤0.028). For lack-of-ghosting averaged across distances, EDOF was significantly better than AOP (p<0.001) but not AOMF (p=0.186). EDOF was significantly better than AOMF and AOP for overall-vision-satisfaction (p≤0.024). CONCLUSIONS: EDOF provides better intermediate and near vision performance than either AOMF or AOP with no difference for distance vision after 1 week of lens wear.