Lluch, S.; Julio, G.; Pujol, P.; Merindano, M. Graefe's archive for clinical and experimental ophthalmology Vol. 254, num. 1, p. 143-148 DOI: 10.1007/s00417-015-3186-9 Data de publicació: 2016-01-01 Article en revista
Background Optical coherence tomography (OCT) has become
a very useful tool to study in vivo different ocular structures
and to improve differential diagnosis and management of
many ocular pathologies. This study aims to identify pterygium
alterations that trigger characteristic OCT images, and
analyze if this pattern correctly demarcates lesion boundary.
Methods Thirty-two patients, 22 men, and ten women, aged
between 26 and 56 (mean age 40.5±6.9) with symptomatic
primary pterygium were recruited. After excision, lesion images
were obtained by high-definition OCT. Specimens were
stained with hematoxylin–eosin (H&E), antivimentin for all
mesenchymal origin cells and altered limbal basal cells, CD45
for lymphocyte and macrophage cells, CD1a for Langerhans
cells, and S100 for melanocyte and Langerhans cells.
Results The typical OCT wedge-shape hyperreflective mass
was evident only by vimentin antibody and included, mainly,
fibroblasts but also immune cells (verified by CD45) in a rich
network of collagen fibers. The mass apex, often extended
centripetally as a thin subepithelial line, hyperreflective by
OCT, was formed by a row of fibroblasts under an apparently
intact Bowman’s layer, as vimentin samples revealed.
Hyperreflective epithelium overlying the mass showed a great
number of vimentin-positive infiltrated cells such as melanocytes,
Langerhans cells, and lymphocytes (identified by the
other biomarkers). H&E staining revealed the presence of
goblet cells. Nevertheless, only vimentin staining revealed
the presence of altered basal cells above partially dissolved
or apparently intact Bowman’s layer, coinciding in this last
case with the fibroblast subepithelial line. In most of the cases
(72 %), the altered cells occupied a basal segment shorter than
the fibroblast subepithelial line but in some specimens, these
cells exceeded the fibroblast line length.
Conclusions This study demonstrated the great visual accordance
between pterygium OCT images and vimentin staining.
Alteration in collagen arrangement, infiltration of inflammatory
cells, and fibroblast subepithelial line in the lesion apex
were the main histological changes responsible for the anomalous
hyperreflectivity of the OCT pattern. By contrast, altered
basal cells located in the basal epithelial layer of the
pterygium head could not be detected by OCT, which might
generate lesion size underestimation.
Julio, G.; Lluch, S.; Pujol, P.; Merindano, M.; Marques, M.S. Optometry and vision science Vol. 92, num. 7, p. 790-795 DOI: 10.1097/OPX.0000000000000622 Data de publicació: 2015-07-01 Article en revista
Purpose To analyze conjunctival cytological features 1 month after pterygium excision using limbo-conjunctival autograft (LCA) with and without intraoperative mitomycin C and to assess tissue short-term evolution in both situations.; Methods Fifty-nine primary nasal pterygia from 59 patients were excised with LCA. Twenty-nine were treated with intraoperative mitomycin C 0.02% (MMC+) and 30 were treated without it (MMC-). Impression cytology was performed in nasal and temporal conjunctiva before and 1 month after the excision. Goblet cell density (GCD) and nucleus-to-cytoplasm nongoblet epithelial cell ratio were quantified.; Results Surgical strategy comparisons (intergroup comparisons): All the preoperative data were, in mean, within the reference range, except for a slight goblet cell hyperplasia in the area of the lesion in MMC+ but no significant differences were found between the groups (p = 0.079 for GCD and p = 0.245 for nucleus-to-cytoplasm ratio; analysis of variance). Clinically relevant differences after surgery were only shown in nasal GCD that was significantly lower in MMC+ than in MMC- (p = 0.000; analysis of variance), with the mean value in MMC+ slightly below normal values whereas that in MMC- remained normal. Tissue evolution (intragroup comparisons): No clinically relevant changes were found in MMC-. Data from MMC+ displayed no changes 1 month after surgery, except for nasal GCD that showed a significant reduction (p = 0.000; paired t test). Nevertheless, this GCD decrease was more modest than that previously described using mitomycin C without autograft, because in the present study, nasal GCD was not lower but similar to postoperative temporal data of the same eye (p = 0.164; paired t test).; Conclusions Limbo-conjunctival autograft is a good technique for conjunctiva early recovery. When mitomycin C was added, the GCD reduction was lower than described using other surgical techniques. Mitomycin C, in optimal concentration and exposure, associated with LCA could be a good clinical option to minimize pterygium recurrence.
PURPOSE: To evaluate the effect of pterygium size and excision on corneal astigmatism before, after surgery.
METHODS: Thirty two eyes with pterygium, were operated using the limbal-conjunctival autograft technique. Corneal topography was performed preoperatively, one, and 3 months after the intervention.
RESULTS: A significant correlation (p < 0.05) was obtained berween pterygium length and preoperative astigmatism, but no correlation was observed berween length and astigmatism at any timepoint. A statistically significant reduction was found berween pre-surgical astigmatism and astigmatism at one and three months. No differences were observed berween one and 3 months. No significant differences were found when comparing the presurgical and postsurgical astigmatism axis.
CONCLUSIONS: Pterygium surgery with limbal-conjunctival autograft moderarely reduces corneal astigmatism. Preoperative astigmatism is associated with the size of the
Quevedo, L.; Aznar, J.; Merindano, M.; Cardona, G.; Solé, J. Research quarterly for exercise and sport Vol. 82, num. 4, p. 644-651 DOI: 10.1080/02701367.2011.10599801 Data de publicació: 2011-12 Article en revista
Julio, G.; Merindano, M.; Lluch, S.; Caum, C. International Conference on the Tear Film & Ocular Surface: Basic Science and Clinical Relevance p. 77 Data de presentació: 2010-09-23 Presentació treball a congrés
Julio, G.; Merindano, M.; Lluch, S.; Caum, C. International Conference on the Tear Film & Ocular Surface: Basic Science and Clinical Relevance p. 76-77 Data de presentació: 2010-09-23 Presentació treball a congrés
The importance of vision in life is unquestionable. It is because of this that optometry, as a science of vision focused in measurement and analysis of visual function, has been developing techniques and instruments to evaluate its functionality in various contexts. Sport has become a social phenomenon, as evidenced by an increasing trend towards active participation, both professionally and recreationally. In order to enhance athletic performance, many have looked towards the sciences (medicine, biomechanics, psychology) for answers. With the specialization of sports vision, optometry has been particularly useful. The importance of the science of vision relating to sports is easily justified by considering that, in general, vision plays a dominant role in athletic success since the majority of external stimuli that athletes have to react to come through the visual system. One of the most critical areas that Sports Vision incorporates is the specific screening of visual capacities related to sports performance. If we consider the dynamic characteristics of most sporting modalities that generally involve constant environmental changes, sudden and fast movements of players and ball, speed, etc., we have to accept the premise that action sports require visual performance evaluation that is different from normal vision testing, since routine testing only samples static vision. Assessment of specific sports-related visual abilities includes peripheral vision, visual reaction time or dynamic visual acuity. In reference to the evaluation of dynamic visual acuity, defined as the ability to resolve a target under conditions of relative motion between the observer and the test stimulus, it must be noted that methods developed to date for its measurement have not been, in general, psychometrically validated, and are too cumbersome and unwieldy to find a place in clinical practice or in field situations. This lack of proper equipment explains much the difficulty of establishing objective, precise and reliable measurements of a visual skill, considered, not only from the sporting context but also from road safety or aircraft operating, as one of the most predictive of real-world task performances, especially in dynamic conditions." Additionally, the need to improve our daily work giving visual attention to elite athletes in the Olympic Training Centre in Sant Cugat del Vallés has led us to develop this doctoral dissertation, with the design of the DinVA 3.0., a computer assisted test for the measurement of dynamic visual acuity. The efficacy of our instrument has been supported by four experimental studies. The first three, included into the psychophysics context, have allowed us to find the legitimacy of the DinVA test measurement by establishing its construct validity, as well as internal and temporal consistency. The last experiment is a differential study where we compared the results of dynamic visual acuity obtained by a sample of elite water polo players and a group of totally sedentary students of Optometry. The obtained results have shown that speed, contrast and direction of displacement of the stimulus significantly affect dynamic visual acuity, supporting the construct validity of the DinVA3.0. Additionally, we have verified that our instrument to measure dynamic visual acuity has a high degree of internal validity, as well as a high test-retest reliability of the obtained measures. Finally, we have been able to establish that athletic training seems to improve dynamic visual acuity. In conclusion, with this doctoral dissertation we aim at offering both, clinicians and researchers, a standardized and typified instrument that allows a solid and specific measure of dynamic visual acuity depending on the application context. It is easy to use, offers the possibility of training, and does not require more equipment than something so common and ubiquitous as a computer.
Premi extraordinari doctorat curs 2007-2008, àmbit d’Enginyeria Civil
La descripción del flujo de fluidos involucra la solución de las ecuaciones de Navier-Stokes compresible, un problema muy complejo cuya estructura matemática no es del todo comprendida. Por lo tanto, mediante análisis asintótico, se pueden derivar modelos simplificados bajo ciertas hipótesis sobre el problema hechas en términos de parámetros adimensionales que miden la importancia relativa de los diferentes procesos físicos. Los flujos a baja velocidad se pueden describir por diferentes modelos que incluyen las ecuaciones de Navier Stokes incompresible cuya matemática es mucho mas conocida. Sin embargo, algunos flujos importantes no se pueden considerar incompresibles debido a la presencia de efectos térmicos. En esta clase de problemas se pueden derivar otra clase de ecuaciones simplificadas: las ecuaciones de Boussinesq y las ecuaciones de bajo numero de Mach.
La complejidad de estos problemas matemáticos hace que su solución numérica sea muy difícil. En estos problemas el método de los elementos finitos es inestable, lo que en la práctica implica soluciones numéricas que presentan oscilaciones nodo a nodo de naturaleza no física. En las ecuaciones de Navier Stokes incompresible, dos fuentes bien conocidas de inestabilidad son la condición de incompresibilidad y la presencia del término convectivo. Muchas técnicas de estabilización utilizadas hoy en día se basan en la separación de escalas, descomponiendo la incógnita en una parte gruesa inducida por la discretización del domino y una parte fina de subescala. Modelar la subescala y su influencia conduce a un problema modificado para la escala gruesa que resulta estable.
Aunque las técnicas de estabilización son ampliamente utilizadas hoy en día, importantes problemas permanecen abiertos. Contribuyendo a su comprensión, en este trabajo se analizan varios aspectos del modelado de las subescalas. Para problemas escalares de segundo orden, se encuentra la dependencia de la subescala con el tamaño de la malla en el caso general de mallas anisótropas. Estas ideas son extendidas a sistemas de ecuaciones para considerar el problema de Oseen. También se analiza el modelado de las subescalas en problemas transitorios, obteniendo un mejor esquema de integración temporal para el problema de escala gruesa. Para considerar flujos a baja velocidad, se presenta la extensión de estas técnicas a problemas no lineales acoplados, lo que esta íntimamente relacionado con el problema del modelado de la turbulencia, que es un tema en si mismo.
Los flujos acoplados térmicamente, aparte del interés intrínseco que merecen, son importantes desde un punto de vista ingenieril. Una solución precisa del problema de flujo es necesaria para definir las cargas térmicas sobre las estructuras, que en muchos casos responden fuertemente, haciendo el problema acoplado. Esta clase de problemas, que motivaron este trabajo, incluyen la respuesta estructural en el caso de un incendio.
A general description of a fluid flow involves the solution of the compressible Navier-Stokes equations, a very complex problem whose mathematical structure is not well understood. Therefore, simplified models can be derived by asymptotic analysis under some assumptions on the problem, made in terms of dimensionless parameters that measure the relative importance of different physical processes. Low speed flows can be described by several models including the incompressible Navier Stokes equations whose mathematical structure is much better understood. However many important flows cannot be considered as incompressible, even at low speed, due to the presence of thermal effects. In such kind of problems another class of simplified equations can be derived: the Boussinesq equations and the Low Mach number equations. The complexity of these mathematical problems makes their numerical solution very difficult. For these problems the standard finite element method is unstable, what in practice means that node to node oscillations of non physical nature may appear in the numerical solution. In the incompressible Navier Stokes equations, two well known sources of numerical instabilities are the incompressibility constraint and the presence of the convective terms. Many stabilization techniques used nowadays are based on scale separation, splitting the unknown into a coarse part induced by the discretization of the domain and a fine subgrid part. The modelling of the subgrid scale and its influence leads to a modified coarse scale problem that now can be shown to be stable. Although stabilization techniques are nowadays widely used, important problems remain open. Contributing to their understanding, several aspects of the subgrid scale modelling are analyzed in this work. For second order scalar problems, the dependence of the subgrid scale on the mesh size, in the general anisotropic case, is clarified. These ideas are extended to systems of equations to consider the Oseen problem. The modelling of the subgrid scales in transient problems is also analyzed, leading to an improved time discretization scheme for the coarse scale problem. To consider low speed flow models, the extension of these techniques to nonlinear and coupled problems is presented, something that is intimately related to the problem of turbulence modelling, which a entire subject on its own right. Thermally coupled flow problems, despite the intrinsic interest they deserve, are important from an engineering point of view. An accurate solution of a flow problem is needed to define thermal loads on structures which, in many cases have a strong response, making the problem coupled. This kind of problems, that motivated this work, include the problem of a structural response in the case of fires.
Peces, M.; Merindano, M.; Pinedo, I.; Anadón-Baselga, M.; Capo, M.A Microscopy 2001. Symposia on biological applications of microscopy: microscopy in medicine and environmental sciences. p. 1 Presentació treball a congrés