RESUMEN

A challenging issue in photoacoustic biomedical imaging is to take into account the presence of dispersive acoustic media, since these are prone to induce amplitude attenuation and scattering of the photoacoustic frequency components. These perturbations are largely the cause for which the photoacoustic tomographic image reconstruction from projections lacks a plane-wave transport formalism. Attending this problem, we further develop an analytic formalism of the transport and its numerical implementation accounting for dispersive acoustic media. We differentiate three variations of an acoustically perturbing media. Our object of interest is a numerical description of the light absorption map of a coronal human breast image. Then, we analyze conditions for which the propagation of photoacoustic perturbations can obey the generalized Heaviside telegraph equation. In addition, we provide a study of the causality consistency of the wave propagation models. We observe transport implications due to the presence of dispersive acoustic media and derive model adjustments that include attenuation and diffusion approximations within the two-dimensional forward problem. Next, we restore the inverse problem description with the deduced perturbation components. Finally, we solve the nonlinear inverse problem with a numerical strategy for a filtered backprojection reconstruction. At a stage prior to the image reconstruction, we compensate for the effect of acoustic attenuation and diffusion to calculate the inversions of the wave perturbations located within the projections. In this way, we manage to significantly reduce reconstruction artifacts. In consequence, we prevent the use of some additional image processing of noise reduction. We demonstrate a feasible strategy on how to solve the stated nonlinear inverse problem of photoacoustic tomography accounting for dispersive acoustic media. In particular, we emphasize efforts to achieve an analytical description, and thus an algorithm is placed, for imaged sound perturbations to be cleaned from acoustic scattering in a simplified manner.

Asunto(s)

Procesamiento de Imagen Asistido por Computador/métodos , Técnicas Fotoacústicas/métodos , Procesamiento de Señales Asistido por Computador , Tomografía Óptica/métodos , Algoritmos , Mama/diagnóstico por imagen , Femenino , Humanos , Fantasmas de Imagen

Asunto(s)

Humanos , Lactante , Preescolar , Niño , Adolescente , Fondo de Ojo , Tomografía Óptica/métodos , Tomografía de Coherencia Óptica/métodos

RESUMEN

Objetivo: determinar la utilidad de la microperimetría y la tomografía óptica coherente en la detección de daño retinal subclínico por cloroquina. Métodos: estudio prospectivo, observacional y analítico en pacientes consumidores de cloroquina, atendidos en la consulta de Neuroftalmología del Instituto Cubano de Oftalmología Ramón Pando Ferrer, entre septiembre 2010 y octubre 2011. Fueron incluidos 44 ojos. Se realizaron exámenes para evaluar función (psicofísica visual y microperimetría) y estructura (biomicroscopia y tomografía óptica coherente). Resultados: la edad promedio fue de 43 años con una dosis acumulada de cloroquina de 182 g y un tiempo de consumo inferior a cinco años. Existió relación significativa entre la dosis acumulada y las variables siguientes: visión del color (-0,495; p= 0,001), grosor retinal peripapilar temporal (-0,353; p= 0,019) e inferior (-0,336; p= 0,026), macular central (-0,652; p= 0,000) y sensibilidad retinal por microperimetría (-0,436; p= 0,003) con alteraciones funcionales y estructurales en relación con el incremento de la dosis acumulada. Conclusiones: se demostró que es posible detectar daño retinal funcional temprano mediante microperimetría y tomografía óptica coherente en pacientes consumidores de cloroquina, en presencia de otros estudios funcionales y biomicroscopia normales. Unido a la tomografía óptica coherente el microperímetro puede constituir una útil herramienta para pesquisa de toxicidad retiniana(AU)

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Objective: to determine the usefulness of microperimetry and of the optical coherence tomography in the detection of subclinical retinal damage due to chloroquine. Methods: prospective, observational and analytical study in patients taking chloroquine, who were seen at the Neuro-ophthalmology service of "Ramón Pando Ferrer" Institute of Ophthalmology from September 2010 through October 2011. Forty four eyes were included. Tests were performed to assess function (visual psychophysics and microperimetry) and structure (biomicroscopy and optical coherence tomography). Results: mean age was 43 years with a cumulative dose of 182 g and less than 5 years taking this drug. There was significant correlation between the cumulative dose of chloroquine and the following variables: color vision (-0.495, p = 0.001), temporal peripapillary retinal thickness (-0.353, p= 0.019) and lower (-0.336, p = 0.026), central macular (-0.652, p = 0.000) and retinal sensitivity by microperimetry (-0.436, p= 0.003) with functional and structural changes related to the increase in cumulative dose. Conclusions: it was demonstrated that it is possible to detect early functional retinal damage by using microperimetry and optical coherence tomography in patients taking chloroquine, despite normal results of other functional studies and of biomicroscopy. The combination of microperimetry and optical coherence tomography may be a useful screening tool for retinal toxicity(AU)

Asunto(s)

Humanos , Masculino , Femenino , Perforaciones de la Retina/inducido químicamente , Perforaciones de la Retina/diagnóstico , Cloroquina/efectos adversos , Tomografía Óptica/métodos , Pruebas del Campo Visual/métodos , Estudios Prospectivos , Estudios Observacionales como Asunto

RESUMEN

Objetivo: determinar la utilidad de la microperimetría y la tomografía óptica coherente en la detección de daño retinal subclínico por cloroquina. Métodos: estudio prospectivo, observacional y analítico en pacientes consumidores de cloroquina, atendidos en la consulta de Neuroftalmología del Instituto Cubano de Oftalmología Ramón Pando Ferrer, entre septiembre 2010 y octubre 2011. Fueron incluidos 44 ojos. Se realizaron exámenes para evaluar función (psicofísica visual y microperimetría) y estructura (biomicroscopia y tomografía óptica coherente). Resultados: la edad promedio fue de 43 años con una dosis acumulada de cloroquina de 182 g y un tiempo de consumo inferior a cinco años. Existió relación significativa entre la dosis acumulada y las variables siguientes: visión del color (-0,495; p= 0,001), grosor retinal peripapilar temporal (-0,353; p= 0,019) e inferior (-0,336; p= 0,026), macular central (-0,652; p= 0,000) y sensibilidad retinal por microperimetría (-0,436; p= 0,003) con alteraciones funcionales y estructurales en relación con el incremento de la dosis acumulada. Conclusiones: se demostró que es posible detectar daño retinal funcional temprano mediante microperimetría y tomografía óptica coherente en pacientes consumidores de cloroquina, en presencia de otros estudios funcionales y biomicroscopia normales. Unido a la tomografía óptica coherente el microperímetro puede constituir una útil herramienta para pesquisa de toxicidad retiniana

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Objective: to determine the usefulness of microperimetry and of the optical coherence tomography in the detection of subclinical retinal damage due to chloroquine. Methods: prospective, observational and analytical study in patients taking chloroquine, who were seen at the Neuro-ophthalmology service of "Ramón Pando Ferrer" Institute of Ophthalmology from September 2010 through October 2011. Forty four eyes were included. Tests were performed to assess function (visual psychophysics and microperimetry) and structure (biomicroscopy and optical coherence tomography). Results: mean age was 43 years with a cumulative dose of 182 g and less than 5 years taking this drug. There was significant correlation between the cumulative dose of chloroquine and the following variables: color vision (-0.495, p = 0.001), temporal peripapillary retinal thickness (-0.353, p= 0.019) and lower (-0.336, p = 0.026), central macular (-0.652, p = 0.000) and retinal sensitivity by microperimetry (-0.436, p= 0.003) with functional and structural changes related to the increase in cumulative dose. Conclusions: it was demonstrated that it is possible to detect early functional retinal damage by using microperimetry and optical coherence tomography in patients taking chloroquine, despite normal results of other functional studies and of biomicroscopy. The combination of microperimetry and optical coherence tomography may be a useful screening tool for retinal toxicity

Asunto(s)

Humanos , Masculino , Femenino , Cloroquina/efectos adversos , Perforaciones de la Retina/diagnóstico , Perforaciones de la Retina/inducido químicamente , Pruebas del Campo Visual/métodos , Tomografía Óptica/métodos , Estudios Observacionales como Asunto , Estudios Prospectivos

RESUMEN

Modern adaptive optics (AO) systems for large telescopes require tomographic techniques to reconstruct the phase aberrations induced by the turbulent atmosphere along a line of sight to a target which is angularly separated from the guide sources that are used to sample the atmosphere. Multi-object adaptive optics (MOAO) is one such technique. Here, we present a method which uses an artificial neural network (ANN) to reconstruct the target phase given off-axis references sources. We compare our ANN method with a standard least squares type matrix multiplication method and to the learn and apply method developed for the CANARY MOAO instrument. The ANN is trained with a large range of possible turbulent layer positions and therefore does not require any input of the optical turbulence profile. It is therefore less susceptible to changing conditions than some existing methods. We also exploit the non-linear response of the ANN to make it more robust to noisy centroid measurements than other linear techniques.

Asunto(s)

Algoritmos , Artefactos , Aumento de la Imagen/métodos , Interpretación de Imagen Asistida por Computador/métodos , Redes Neurales de la Computación , Telescopios , Tomografía Óptica/métodos

RESUMEN

Objetivo: evaluar las características del disco óptico y la capa de fibras neurorretinianas en la sospecha de cierre angular primario, el desempeño de las funciones discriminantes y la influencia del tamaño del disco en estos.Métodos: estudio de serie de casos de corte transversal en 47 ojos (30 pacientes) con sospecha de cierre angular primario. Se utilizó el tomógrafo confocal de barrido láser (HRT 3, Heidelberg Engineering, Alemania). Para el análisis de la influencia del tamaño del disco se consideraron tres grupos: área de disco menor de 1,6 mm2, entre 1,6 y 2 mm2 y mayor de 2,0 mm2.Resultados: el área de disco se relacionó positivamente con el área de copa, área de anillo, volumen de copa, área de sección transversal de la capa de fibras neurorretinianas y tamaño de copa (p=0,023, p=0,009, p=0,022, p=0,026, p=0,020 respectivamente) y negativamente con la curvatura horizontal de la capa de fibras neurorretinianas (p=0,019). Hubo una relación significativa con la variación de la altura del contorno (p=0,008), fundamentalmente a expensas de las diferencias de los discos pequeños con los medianos. Para las funciones MRA, GPS y FSM el mejor desempeño fue en el disco pequeño (aproximandamente 92 porciento de concordancia con el disco sano en cada una). La función RB mostró la mayor coincidencia (100, 96 y 100 porciento; según grupos de área de disco), mientras el GPS, la menor (92, 72 y 55,6 porciento respectivamente).Conclusiones: el área de disco se relaciona con el área de copa, área de anillo, volumen de copa, área de sección transversal y curvatura horizontal de la capa de fibras neurorretinianas, tamaño de copa y variación de altura del contorno. Las funciones MRA, GPS y FSM identifican el disco sano con mayor certeza cuando es pequeño. La función RB se desempeña mejor mientras el GPS peor, independientemente del valor de área de disco(AU)

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Objective: to evaluate the characteristics of the optic disc and of the retinal nerve fiber layer in the suspected primary angle closure, the performance of glaucomatous discriminant functions, and the influence of the optic disc size in the results.Methods: a cross-sectional case series study in 47 eyes (30 patients) with suspected primary angle-closure, for which the confocal laser tomography (HRT 3, Heidelberg Engineering, Germany), was used to obtain the images. The influence of the optic disc size was analized in 3 groups: < 1,6mm2, 1,6 - 2,0 mm2 y > 2,0 mm2.Results: the disc area was positively related to the cup area, the rim area, the cup volume, the retinal nerve fiber layer cross sectional area, and the cup size (p=0,023, p=0,009, p=0,022, p=0,026, p=0,020 respectively) and negatively related with the horizontal curvature of the retinal nerve fiber layer (p=0,019). There was a significant relation to the variation of contour height (p=0,008), particularly to differences between small and medium size discs. Discriminant functions such as MRA, GPS and FSM performed better in small discs (approximately 92 percent of agreement with the normal discs for each one). The RB function obtained the greater coincidence (100, 96 and 100 per cent for respective groups of disc areas), whereas GPS obtained the smallest (92, 72 and 55,6 percent respectively).Conclusions: the disc area is related to cup area, rim area, cup volume, retinal nerve fiber layer cross sectional area, retinal nerve fiber layer horizontal curvature, cup size and the variation of contour height. The MRA, GPS and FSM discriminant functions identify better the normal optic disc when it is small. The RB function performs the best whereas the GPS performs the worst, regardless of the disc area(AU)

Asunto(s)

Humanos , Masculino , Femenino , Adolescente , Adulto Joven , Adulto , Persona de Mediana Edad , Anciano , Glaucoma de Ángulo Cerrado/diagnóstico , Tomografía Óptica/métodos , Disco Óptico/patología , Epidemiología Descriptiva

RESUMEN

OBJETIVO: Correlacionar área do disco óptico com parâmetros geométricos e biomecânicos da córnea. MÉTODOS: Estudo retrospectivo nos arquivos de pacientes do Instituto de Olhos Renato Ambrósio a fim de se identificar os pacientes que realizaram exames HRT (Heidelberg Retina Tomography), Pentacam e ORA. A retinografia digital foi revisada de modo a se classificar na escala DDLS (Disc Damage Likelihood Scale). RESULTADOS: 244 olhos de 122 pacientes (75 mulheres) foram incluídos no estudo. A média de idade foi de 47,2 anos (de 8 a 97 anos, desvio padrão de 21,7). Não houve correlação significante entre área do disco e nenhuma das medidas de PIO (IOPg, IOPcc). Encontrou-se uma relação negativa significativa com CRF (r=-0,1337, p=0,0263). A relação com histerese foi também negativa (-0,1123), mas o valor p foi maior que 0,05 (0,0625). Não houve correlação significante entre área do disco e progressão paquimétrica mínima ou média. Entretanto, observou-se correlação significante e positiva entre a área do disco e astigmatismo corneano (Delta K), sendo de 1,15 (p=0,0129). CONCLUSÃO: Existe uma correlação negativa entre a área do disco óptico e os parâmetros biomecânicos e estruturais da córnea. Tal correlação pode ser parte da explicação da córnea ser um fator de risco para maior susceptibilidade do nervo óptico para neuropatia glaucomatosa.

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PURPOSE: To correlate optic disc size geometry, corneal architecture and biomechanics. METHODS: Optic disc area and geometry was accessed by HRT III (Heidelberg Retina Tomography - Heidelberg eng), Pentacam (Oculus) was used for accessing IOP and corneal parameters and ORA (Ocular Response Analyze - Reichert) was utilized to access corneal biomechanical properties. Classification based DDLS (Disc Damage Likelihood Scale) scale from retinography was performed. Settings: Instituto de Olhos Renato Ambrósio. RESULTS: 244 eyes of 122 patients (75 female) were included. The average age was 47,2 years (from 8 to 97 years). A significant negative correlation was found between disc optic size and CRF (r=0,1337, p=0,0263). A small trend was also found between optic nerve size and hysteresis (r=-0,1123, p=0,0625). A significant negative correlation was also found between disc optic size and thinnest point, maximal pachymetri progression, corneal volume at (1, 4 e 6mm) and difference from thinnest and central value (p<0,05). The highest negative correlation was with corneal volume within 4mm in diameter (r=-1,887; p=0,0017). A positive correlation between size of optic disc and cornea astigmatism (delta K), was found (r= 1,15; p=0,0129). CONCLUSION: There is a negative correlation between optic disc size and corneal thickness and biomechanical properties. These findings may help explaining susceptibility for the development of glaucoma neuropathy in some cases.

Asunto(s)

Humanos , Masculino , Femenino , Niño , Adolescente , Adulto , Persona de Mediana Edad , Anciano , Anciano de 80 o más Años , Disco Óptico/diagnóstico por imagen , Tonometría Ocular/métodos , Córnea/diagnóstico por imagen , Tomografía Óptica/métodos , Paquimetría Corneal/métodos , Tamaño de los Órganos , Fenómenos Biomecánicos , Enfermedades del Nervio Óptico , Glaucoma de Ángulo Abierto , Hipertensión Ocular , Estudios Retrospectivos , Factores de Riesgo , Población Blanca , Susceptibilidad a Enfermedades , Presión Intraocular

RESUMEN

La OCT (Tomografía de Coherencia Óptica) es una técnica de exploración tele oftalmológica moderna que se aplica para estudiar en vivo el segmento anterior y posterior, aunque en la actualidad su uso es mayor para la obtención de imágenes de la retina. Con un rápido chequeo del paciente se podrá valorar y estudiar a unos niveles, hasta ahora no conseguidos con otros medios, el estado de la retina y al mismo tiempo detectar con gran precisión distintas patologías y su evolución. En este trabajo se revisó la OCT en cuanto a la base de su funcionamiento y su importancia en el diagnóstico de las patologías retinianas y neurooftalmológicas. Se tuvo en cuenta la literatura disponible sobre el tema y los resultados se representan en Microsoft Word(AU)

Asunto(s)

Humanos , Masculino , Femenino , Tomografía Óptica/métodos , Oftalmopatías/diagnóstico , Telemedicina , Equipo para Diagnóstico , Técnicas de Diagnóstico Oftalmológico

RESUMEN

The objective of the present study was to evaluate changes in optic nerve head parameters, measured by confocal laser tomography, before and after trabeculectomy in order to identify outcome measures for the management of glaucoma. The optic nerve head of 22 eyes (22 patients) was analyzed by confocal laser tomography with the Heidelberg retinal tomogram (HRT) before and after trabeculectomy. The median time between the first HRT and surgery was 4.6 months (mean: 7.7 +/- 8.3) and the median time between surgery and the second HRT was 10.8 months (mean: 12.0 +/- 6.8). The patients were divided into two groups, i.e., those with the highest (group A) and lowest (group B) intraocular pressure (IOP) change after surgery. Differences in the 12 standard topographic parameters before and after surgery for each group were evaluated by the Wilcoxon signed rank test and the differences in these parameters between the two groups were compared by the Mann-Whitney rank sum test. Multiple regression analysis was used to evaluate the influence of the change in IOP (DeltaIOP and DeltaIOP%) and the changes in the other parameters. There were significant differences in the HRT measures before and after surgery in group A only for cup volume. In group B, no parameter was statistically different. The changes in group A were not significantly different than those in group B for any parameter (P > 0.004, Bonferroni correction for multiple comparisons). DeltaIOP and DeltaIOP% had a statistically significant effect on Delta cup disk area, Delta cup volume and Delta mean cup depth. Changes in cup shape size were influenced significantly only by DeltaIOP. Some optic disc parameters measured by HRT presented a significant improvement after filtering surgery, depending on the amount of IOP reduction. Long-term studies are needed to determine the usefulness of these findings as outcome measures in the management of glaucoma.

Asunto(s)

Glaucoma/cirugía , Disco Óptico/anatomía & histología , Trabeculectomía , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Tomografía Óptica/métodos , Resultado del Tratamiento

RESUMEN

The objective of the present study was to evaluate changes in optic nerve head parameters, measured by confocal laser tomography, before and after trabeculectomy in order to identify outcome measures for the management of glaucoma. The optic nerve head of 22 eyes (22 patients) was analyzed by confocal laser tomography with the Heidelberg retinal tomogram (HRT) before and after trabeculectomy. The median time between the first HRT and surgery was 4.6 months (mean: 7.7 ± 8.3) and the median time between surgery and the second HRT was 10.8 months (mean: 12.0 ± 6.8). The patients were divided into two groups, i.e., those with the highest (group A) and lowest (group B) intraocular pressure (IOP) change after surgery. Differences in the 12 standard topographic parameters before and after surgery for each group were evaluated by the Wilcoxon signed rank test and the differences in these parameters between the two groups were compared by the Mann-Whitney rank sum test. Multiple regression analysis was used to evaluate the influence of the change in IOP (deltaIOP and deltaIOP percent) and the changes in the other parameters. There were significant differences in the HRT measures before and after surgery in group A only for cup volume. In group B, no parameter was statistically different. The changes in group A were not significantly different than those in group B for any parameter (P > 0.004, Bonferroni correction for multiple comparisons). deltaIOP and deltaIOP percent had a statistically significant effect on delta cup disk area, delta cup volume and delta mean cup depth. Changes in cup shape size were influenced significantly only by deltaIOP. Some optic disc parameters measured by HRT presented a significant improvement after filtering surgery, depending on the amount of IOP reduction. Long-term studies are needed to determine the usefulness of these findings as outcome measures in the management of glaucoma.

Asunto(s)

Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad , Glaucoma/cirugía , Disco Óptico/anatomía & histología , Trabeculectomía , Estudios Retrospectivos , Resultado del Tratamiento , Tomografía Óptica/métodos