Modelado geométrico personalizado de la córnea humana y su aplicación a la detección de ectasias corneales

[SPA] La córnea es una estructura biológica viva cuya arquitectura presenta una morfología singular, ya sea en un estado natural o patológico. Esta singularidad ha sido caracterizada a lo largo de toda la historia en el campo de la oftalmología y la óptica a través de la generación de modelos genéricos o de modelos personalizados de la córnea humana. Hoy en día, el desarrollo de nuevas tecnologías permite caracterizar la morfología corneal a partir de los denominados equipos topográficos; estos equipos aportan una caracterización personalizada de índole cualitativa y cuantitativa al médico oftalmólogo. Sin embargo, los sistemas de diagnóstico de las patologías corneales están basados en unos índices de valoración de la irregularidad de las superficies corneales que son calculados a partir de algoritmos específicos internos para cada topógrafo corneal y de los cuales se desconoce su programación. Por este motivo en esta tesis doctoral se establece un nuevo procedimiento fundamentado en la geometría computacional para obtener un modelo sólido 3D personalizado in vivo de la córnea humana utilizando herramientas de Diseño Geométrico Asistido por Ordenador. Este modelo virtual reconstruye fidedignamente las superficies de la cara anterior y posterior de la córnea, a partir de unos datos aportados por los topógrafos corneales denominados datos en bruto (sin ningún trato mediante algoritmo) tanto para los ojos de pacientes sanos como para los ojos de pacientes diagnosticados con la patología ectásica más común, el queratocono. A partir del nuevo modelo sólido obtenido, se definen unos índices de caracterización de la morfología corneal basados en variables geométricas, los cuales pueden ser utilizados como unos nuevos índices de diagnóstico de la patología ectásica objeto de estudio debido a que presentan una elevada sensibilidad y especificidad para su diagnóstico. [ENG] The cornea is a living biological structure whose architecture has a unique morphology, either in a natural or diseased condition. This uniqueness has been characterized throughout all history in the field of ophthalmology and optics through the generation of generic or customized models of human cornea. Today, the development of new technologies leads to characterize the corneal morphology from the so‐called topographic devices; these devices provide a personalized qualitative and quantitative characterization of its nature for the ophthalmologist. However corneal pathological diagnosis systems are based on indicators of the irregularity of the corneal surfaces, which are calculated from specific internal algorithms for each corneal topographer and whose programming is unknown. For that reason, this doctoral thesis establishes a new procedure based on computational geometry to obtain a 3D solid model, personalized and in vivo of the human cornea by using Computer Aided Geometrical Design tools. This virtual model represents accurately both the anterior and posterior corneal surfaces from a set of raw data (without any algorithm treatment) provided by the corneal topographers for both healthy corneas and corneas with the most common ectasic disease, the keratoconus. The new solid model obtained is later analyzed to define a set of indices that enable the characterization of the corneal morphology and that are based on geometric variables. These indices can be used as new indicators for the diagnosis of the keratoconus disease due to their high sensibility and specificity.[ENG] The cornea is a living biological structure whose architecture has a unique morphology, either in a natural or diseased condition. This uniqueness has been characterized throughout all history in the field of ophthalmology and optics through the generation of generic or customized models of human cornea. Today, the development of new technologies leads to characterize the corneal morphology from the so‐called topographic devices; these devices provide a personalized qualitative and quantitative characterization of its nature for the ophthalmologist. However corneal pathological diagnosis systems are based on indicators of the irregularity of the corneal surfaces, which are calculated from specific internal algorithms for each corneal topographer and whose programming is unknown. For that reason, this doctoral thesis establishes a new procedure based on computational geometry to obtain a 3D solid model, personalized and in vivo of the human cornea by using Computer Aided Geometrical Design tools. This virtual model represents accurately both the anterior and posterior corneal surfaces from a set of raw data (without any algorithm treatment) provided by the corneal topographers for both healthy corneas and corneas with the most common ectasic disease, the keratoconus. The new solid model obtained is later analyzed to define a set of indices that enable the characterization of the corneal morphology and that are based on geometric variables. These indices can be used as new indicators for the diagnosis of the keratoconus disease due to their high sensibility and specificity.Esta tesis se ha realizado en parte gracias a la financiación del proyecto del Fondo Europeo de Desarrollo Regional (FEDER) y del Ministerio Español de Economía y Competitividad, Instituto Carlos III, Red Temática de Investigación Cooperativa en Salud (RETICS) «Prevención, detección precoz y tratamiento de la patología ocular prevalente, degenerativa y crónica». Subprograma «dioptrio ocular y patologías frecuentes» (RD12/0034/0007).Escuela Internacional de DoctoradoUniversidad Politécnica de CartagenaPrograma Oficial de Doctorado en Tecnologías Industriale

Optical Impact of Corneal Clearance in Healthy Eyes Fitted with Scleral Contact Lenses: A Pilot Study

This pilot study was conducted to evaluate the effect on refraction and optical quality of the increase in the corneal clearance after fitting a specific model of scleral contact lens (ScCL) in healthy subjects. A total of 15 eyes from 15 subjects were enrolled in the study, with evaluation of refraction, ocular aberrations and central corneal clearance with the same model of ScCL (ICD Toric, Paragon Vision Science, Gilbert, AZ, USA), but using 3 different sagittal heights: 4200, 4500 and 4800 µm. Mean values of corneal clearance for each ScCL fitted were 418.1 ± 112.1, 706.5 ± 120.3 and 989.9 ± 117.0 µm, respectively. Significant changes were detected in the spherical equivalent and high-order aberrations, especially coma and spherical aberration, when fitting ScCLs of increasing sagittal heights compared to the pre-fitting values. In conclusion, the increase in central corneal clearance when fitting ScCLs affects refraction, leading to a more myopic refractive error, and inducing an increase in different ocular HOAs. This should be considered when fitting ScCLs, especially multifocal designs.The author David P Piñero has been supported by the Ministry of Economy, Industry and Competitiveness of Spain within the program Ramón y Cajal, RYC-2016-20471

Female leadership in sports clubs

The objective of this study was to determine the type of leadership applied by the directors of amateur sports clubs. This quantitative, descriptive and cross-sectional study was carried out on a sample of 48 directors of sports clubs in total: 23 (47.91%) belonging to collective sports clubs and 25 (52.08%) to individual sports clubs. The study administered the MLQ-X5 Multifactor Leadership Questionnaire (45 items). The answers are collected on a Likert scale ranging from 0 (never) to 4 (almost always). The results indicated that the directors opt for a transformational leadership style (3.24), preferably followed by the corrective leadership type (3.18) and almost the same level as the developer type (3.17). The study concluded that the collective sports directors opt for the style of transformational leadership by being proactive and promoting the achievement of extraordinary goals

Predicting First-Year College Student Retention: Validation of the College Persistence Questionnaire in a Spanish Sample

This paper analyzes the factorial and predictive validity of a Spanish adaptation of the College Persistence Questionnaire (SCPQ) on the retention of first year students (FYS) at university. The participants were 490 FYS from two public universities in Southern Europe (Spain). Factorial analysis of the SCPQ (chi(2)/gl = 1.66, CFI = 0.92, NNFI = 0.91, RMSEA = 0.04) showed six reliable dimensions, similar to those found in the original study: Academic Integration, Social Integration, Supportive Services Satisfaction, Academic Conscientiousness, Degree Commitment and Institutional Commitment. Logistic regression showed that institutional commitment significantly predicted FYS' permanence. The results support SCPQ's validity as an adequate and useful tool for assessing FYS' academic experiences involved in student retention.This research was partially funded by the University of Valencia, grant number SFPIE_DOCE12-79415

Geometrical optimization of thermoforming continuous fibers reinforced thermoplastics with Finite Element Models: A case study

The manufacturing of thermoformed components of continuous fiber-reinforced thermoplastics (CFRTPs) relies on an optimization process owing to a demand for quality and the mechanical requirements. Geometrical optimization is typically based on trial-and-error processes, and delays due to the manufacturing of different prototypes increases the development cost of the final product. In this study, the mechanical behavior of a CFRTPs top mount damping component made of polyamide 6 (PA6) reinforced with long glass fibers (47% in volume) and installed in an automobile differential system was evaluated. This was achieved by developing ad hoc tooling for axial testing. The experimental results were used to validate those obtained using a finite element (FE) model based on the fabricated geometry and mechanical properties of the CFRTPs laminate. Furthermore, a complete mathematical procedure was implemented to address the lack of information on the mechanical moduli and Poisson's ratio in the material datasheet for the FE simulation. This method was based on a Halpin-Tsai model and classical lamination theory with a 3D expansion for out-of-plane mechanical property calculation, wherein Tsai's modulus was obtained for checking purposes. The obtained results were fitted with the test results to validate the developed FE model. In addition, this model was used to further optimize the component geometry. The implementation of in silico models based on FE techniques can be useful for accelerating the development of recyclable CFRTPs for large-scale production, allowing significant weight reduction and lower greenhouse emission without diminishing their reliability and safety throughout their useful life.The authors would like to acknowledge the support of CMP Automotive Group for collaboration in the experimental part and to IGESTEK for the information provided on the composites it manufactures

Análisis de los sistemas actuales en oftalmología para el estudio de enfermedades relacionadas con la modificación geométrica de la arquitectura corneal

[ES] El análisis de la morfología corneal es un procedimiento muy útil en el diagnóstico clínico de determinadas patologías oculares, especialmente las relacionadas con alteraciones ectásicas corneales. Desde la aparición de los sistemas basados en Discos de Plácido a los sistemas que incorporan la fotografía Scheimpflug, existe una variedad de instrumentos que ofrecen la posibilidad de analizar con gran precisión parámetros de la morfología corneal. En esta comunicación se revisan los diversos instrumentos que han sido utilizados para caracterizar la morfología corneal, estando todos influenciados, en mayor o menor medida, por factores como la rapidez de adquisición de datos y la estabilidad de la película lagrimal. [ENG] The analysis of the corneal shape is a very useful process that permits the clinical diagnosis of determined ocular pathologies, especially those related with corneal ectatic disorders. From the appearance of the systems based on the Placido-disc technology to the new systems that combine the accurate Scheimpflug photography, there are a variety of ophthalmic instruments that permit to analyze with high accuracy some parameters of the corneal shape. This communication reviews the different systems that have been used to characterize the corneal morphology, being all of them influenced, to a greater or lesser extent, by factors such as the speed for data acquisition and the stability of the tear film.Centro Universitario de la Defensa. Escuela de Turismo de Cartagena. Escuela Técnica Superior de Ingeniería Industrial UPCT. Escuela Técnica Superior de Ingeniería de Telecomunicación (ETSIT). Escuela de Ingeniería de Caminos y Minas (EICM). Escuela de Arquitectura e Ingeniería de Edificación (ARQ&IDE). Parque Tecnológico de Fuente Álamo. Navantia. Campus Mare Nostrum. Estación Experimental Agroalimentaria Tomás Ferr

Iterative Methods for the Biomechanical Evaluation of Corneal Response. A Case Study in the Measurement Phase

The number of corneal surgeries steadily grew in recent years and boosted the development of corneal biomechanical models. These models can contribute to simulating surgery by reducing associated risks and the need for secondary interventions due to ectasias or other problems related to correcting other diseases. Biomechanical models are based on the geometry obtained with corneal topography, which is affected by intraocular pressure and material properties. Knowledge of stress distribution in the measurement phase is a key factor for improving the accuracy of in silico mechanical models. In this work, the results obtained by two different methods: prestress method and displacements method were compared to evaluate the stress and strain distribution in a general geometric model based on the Navarro eye geometry and two real corneal geometries. The results show that both methods are equivalent for the achievement of the stress distribution in the measurement phase. Stress distribution over the corneal geometry in the measurement phase is a key factor for accurate biomechanical simulations, and these simulations could help to develop patient-specific models and reduce the number of secondary interventions in clinical practice.This publication was carried out in the framework of the Thematic Network for Co‐Operative Research in Health (RETICS) reference number RD12/0034/0007 and RD16/0008/0012, financed by the Carlos III Health Institute—General Subdirection of Networks and Cooperative Investigation Centers (R&D&I National Plan 2008–2011) and the European Regional Development Fund (FEDER). The author David P. Piñero was supported by the Ministry of Economy, Industry, and Competitiveness of Spain within the program Ramón y Cajal, RYC‐2016‐20471

Relationship between Corneal Morphogeometrical Properties and Biomechanical Parameters Derived from Dynamic Bidirectional Air Applanation Measurement Procedure in Keratoconus

The morphogeometric analysis of the corneal structure has become a clinically relevant diagnostic procedure in keratoconus (KC) as well as the in vivo evaluation of the corneal biomechanical properties. However, the relationship between these two types of metrics is still not well understood. The current study investigated the relationship of corneal morphogeometry and volume with two biomechanical parameters: corneal hysteresis (CH) and corneal resistance factor (CRF), both provided by an Ocular Response Analyzer (Reichert). It included 109 eyes from 109 patients (aged between 18 and 69 years) with a diagnosis of keratoconus (KC) who underwent a complete eye examination including a comprehensive corneal topographic analysis with the Sirius system (CSO). With the topographic information obtained, a morphogeometric and volumetric analysis was performed, defining different variables of clinical use. CH and CRF were found to be correlated with these variables, but this correlation was highly influenced by corneal thickness. This suggests that the mechanical properties of KC cornea contribute only in a partial and limited manner to these biomechanical parameters, being mostly influenced by morphogeometry under normal intraocular pressure levels. This would explain the limitation of CH and CRF as diagnostic tools for the detection of incipient cases of KC.This publication was carried out in the framework of the Thematic Network for Co-Operative Research in Health (RETICS) reference number RD12/0034/0007 and RD16/0008/0012, financed by the Carlos III Health Institute—General Subdirection of Networks and Cooperative Investigation Centers (R&D&I National Plan 2008–2011) and the European Regional Development Fund (FEDER). The author David P. Piñero has been supported by the Ministry of Economy, Industry, and Competitiveness of Spain within the program Ramón y Cajal, RYC-2016-20471

3D printed personalized corneal models as a tool for improving patient’s knowledge of an asymmetric disease

Additive manufacturing is a vanguard technology that is currently being used in several fields in medicine. This study aims to evaluate the viability in clinical practice of a patient-specific 3D model that helps to improve the strategies of the doctor-patient assistance. Data obtained from a corneal topographer were used to make a virtual 3D model by using CAD software, to later print this model by FDM and get an exact replica of each patient’s cornea in consultation. Used CAD and printing software were open-source, and the printing material was biodegradable and its cost was low. Clinic users gave their feedback by means of a survey about their feelings when perceiving with their senses their own printed cornea. There was 82 surveyed, 73.8% (9.74; SD: 0.45) of them considered that the model had helped them a lot to understand their disease, expressing 100% of them their intention of taking home the printed model. The majority highlighted that this new concept improves both quality and clinical service in consultation. Custom-made individualized printed models allow a new patient-oriented perspective that may improve the communication strategy from the ophthalmologist to the patient, easing patient’s understanding of their asymmetric disease and its later treatment.This publication has been carried out in the framework of the Thematic Network for Co-Operative Research in Health (RETICS), reference number RD16/0008/0012, financed by the Carlos III Health Institute–General Subdirection of Networks and Cooperative Investigation Centers (R&D&I National Plan 2013–2016) and the European Regional Development Fund (FEDER)

A machine-learning model based on morphogeometric parameters for RETICS disease classification and GUI development

This work pursues two objectives: defining a new concept of risk probability associated with su_ering early-stage keratoconus, classifying disease severity according to the RETICS (Thematic Network for Co-Operative Research in Health) scale. It recruited 169 individuals, 62 healthy and 107 keratoconus diseased, grouped according to the RETICS classification: 44 grade I; 18 grade II; 15 grade III; 15 grade IV; 15 grade V. Di_erent demographic, optical, pachymetric and eometrical parameters were measured. The collected data were used for training two machine-learning models: a multivariate logistic regression model for early keratoconus detection and an ordinal logistic regression model for RETICS grade assessments. The early keratoconus detection model showed very good sensitivity, specificity and area under ROC curve, with around 95% for training and 85% for validation. The variables that made the most significant contributions were gender, coma-like, central thickness, high-order aberrations and temporal thickness. The RETICS grade assessment also showed high-performance figures, albeit lower, with a global accuracy of 0.698 and a 95% confidence interval of 0.623–0.766. The most significant variables were CDVA, central thickness and temporal thickness. The developed web application allows the fast, objective and quantitative assessment of keratoconus in early diagnosis and RETICS grading terms.This publication has been carried out as part of the Thematic Network for Co-Operative Research in Health (RETICS), reference number RD16/0008/0012, financed by the Carlos III Health Institute-General Subdirection of Networks and Cooperative Investigation Centers (R&D&I National Plan 2013-2016), European Regional Development Funds (FEDER), and the Results Valorization Program financed by the Technical University of Cartagena (PROVALOR-UPCT)