Video of the labelling of projected Placido rings through the scanning annulus

The Elliptical Scanning Algorithm is an effective method to individually detect and label the projected rings. It consecutively defines an elliptical annulus of one pixel wide which grows pixel by pixel and sweeps the image, from centre to periphery, until it detects and labels each whole ring. In a way, it works like a snake-annealing algorithm. Active contour models (snakes) are energy-minimising curves that deform to fit image features. Elliptical Scanning Algorithm changes its geometry in order to label reflected rings.

Screening Subclinical Keratoconus With Placido-Based Corneal Indices

Purpose. To assess in a sample of normal, keratoconic, and keratoconus (KC) suspect eyes the performance of a set of new topographic indices computed directly from the digitized images of the Placido rings. Methods. This comparative study was composed of a total of 124 eyes of 106 patients from the ophthalmic clinics Vissum Alicante and Vissum Almería (Spain) divided into three groups: control group (50 eyes), KC group (50 eyes), and KC suspect group (24 eyes). In all cases, a comprehensive examination was performed, including the corneal topography with a Placidobased CSO topography system. Clinical outcomes were compared among groups, along with the discriminating performance of the proposed irregularity indices. Results. Significant differences at level 0.05 were found on the values of the indices among groups by means of Mann-Whitney-Wilcoxon nonparametric test and Fisher exact test. Additional statistical methods, such as receiver operating characteristic analysis and K-fold cross validation, confirmed the capability of the indices to discriminate between the three groups. Conclusions. Direct analysis of the digitized images of the Placido mires projected on the cornea is a valid and effective tool for detection of corneal irregularities. Although based only on the data from the anterior surface of the cornea, the new indices performed well even when applied to the KC suspect eyes. They have the advantage of simplicity of calculation combined with high sensitivity in corneal irregularity detection and thus can be used as supplementary criteria for diagnosing and grading KC that can be added to the current keratometric classifications.

El espacio, la luz y lo santo. La arquitectura del templo cristiano

Es conciso y profundo el estudio que hace el autor de las variables religiosas que le cuadran, a pesar de aquella contradicción que también él registra (esta inevitable tensión entre la intemperie y la arquitectura religiosa), al diseño del templo cristiano. Con sentido pedagógico -y filosófico- parte de los conceptos previos a toda habitación -espacio, volumen, masa...- para luego aplicarse con brillante racionalidad técnica y religiosa, a proponer relaciones entre lo fijo y lo incontenible, entre lo construible y la liturgia que lo habitará. Accesible para profanos de uno y otro campo, el arquitectónico y el teológico, la obra que recomendamos con estas líneas, es un ejercicio, al que os invito, de contemplación e imaginación, que no otra cosa opera por debajo de los ritos, las palabras y los signos que hacen de los templos cristianos lugares de vida, esperanza y, ¡qué necesidad tenemos de ello...!, humanidad.

El Caballero Cubierto en la Procesión del Santo Entierro de Cristo

Hermandad del Caballero Cubierto, Orihuela; Hermandad de los Pilares de Nuestra Señora de la Soledad; Ayuntamiento de Orihuela