Local curvatures and its measurements of an optical surface or a wavefront: a review

The mathematical tools to calculate surface and wavefront local curvatures have been growing in importance because, when studying and evaluating some optical systems, the local curvature becomes extremely important. Many practical methods have been created to measure the wavefront shape and local curvatures as well as many mathematical tools to describe them. These methods are very useful in ophthalmology mainly for corneal evaluation, but the methods are now being used in other fields of optical metrology, especially in optical testing, interferometric wavefront description, and others. In some instruments and optical devices, mainly ophthalmic and optometric instruments, the local curvatures distribution over the pupil of an optical system is more important than the wavefront topography. A typical example is a human eye, in which corneal topographers, eye aberrometers, and several other instruments are used to measure the local curvatures. In particular, the main aspects of the curvature calculation at a given point for different slopes in any direction are introduced. The principal curvatures, mean, Gaussian, cylindrical, tangential, and sagittal curvatures are described. In the second part of this review, we describe the main methods and devices for wavefront sensing, measuring elevations, slopes, or curvatures. We conclude with a description of some methods to measure and calculate local curvatures from wavefront sensors by measuring the wavefront elevations, the transverse aberrations (slopes), or directly the curvature

Automated detection of photoreceptors in in-vivo retinal images

The inclusion of adaptive optics (AO) into ophthalmic imaging technology has allowed the study of histological elements of retina in-vivo, such as photoreceptors, retinal pigment epithelium (RPE) cells, retinal nerve fiber layer and ganglion cells. The high-resolution images obtained with ophthalmic AO imaging devices are rich with information that is difficult and/or tedious to quantify using manual methods. Thus, robust, automated analysis tools that can provide reproducible quantitative information about the tissue under examination are required. Automated algorithms have been developed to detect the position of individual photoreceptor cells and characterize the RPE mosaic. In this work, an algorithm is presented for the detection of photoreceptors. The algorithm has been tested in synthetic and real images acquired with an Adaptive Optics Scanning Laser Ophthalmoscope (AOSLO) and compared with the one developed by Li and Roorda. It is shown that both algorithms have similar performance on synthetic and cones-only images, but the one here proposed shows more accurate measurements when it is used for cones-rods detection in real images.La inclusión de la óptica adaptativa (adaptive optics, AO) en la tecnología de imágenes oftálmicas ha permitido el estudio in-vivo de los elementos histológicos de retina, como los fotorreceptores, células del epitelio pigmentario de la retina (retinal pigment ephitelium, RPE), la capa de fibras nerviosas de la retina y células ganglionares. Las imágenes de alta resolución obtenidas con dispositivos oftálmicos con AO son ricos en información, que es difícil y/o tediosa de cuantificar por medio de métodos manuales. Por lo tanto, se requieren herramientas de análisis automatizadas robustas que puedan proporcionar información cuantitativa reproducible del tejido bajo examen. Algoritmos automatizados han sido desarrollados para detectar la posición de células individuales fotorreceptoras y caracterizar el mosaico RPE. En este trabajo, se presenta un algoritmo para la detección de los fotorreceptores. El algoritmo ha sido probado en imágenes sintéticas y reales adquiridas con un oftalmoscopio de barrido láser con óptica adaptativa (Adaptive Optics Scanning Laser Ophthalmoscope, AOSLO) y comparado con el desarrollado por Li y Roorda. Se muestra que ambos algoritmos tienen un rendimiento similar en imágenes sintéticas e imágenes con sólo conos, pero el algoritmo propuesto muestra mediciones más precisas cuando se utiliza para la detección de conos-bastones en imágenes reales

Determinants of penetrance and variable expressivity in monogenic metabolic conditions across 77,184 exomes

Penetrance of variants in monogenic disease and clinical utility of common polygenic variation has not been well explored on a large-scale. Here, the authors use exome sequencing data from 77,184 individuals to generate penetrance estimates and assess the utility of polygenic variation in risk prediction of monogenic variants

Physical optics and light measurements

Physical Optics and Light Measurement

Geometrical and instrumental optics

Geometrical and Instrumental Optic