Impact of lens material on objective refraction in eyes with trifocal diffractive intraocular lenses

Purpose: Compare subjective (Rx) and objective (ObjRx) refractions outcomes with two autorefractors models and an aberrometer in eyes implanted with a hydrophobic trifocal IOL (FineVision POD F GF, Physiol, Liége, Belgium) and a hydrophilic one (FineVision POD F, Physiol, Liége, Belgium). Methods: Prospective comparative cohort study, with 100 subjects randomly assigned to either the POD F group (n = 50) or the POD F-GF group (n = 50). Postoperative eye examinations at 1-month visit included seven result sets, one for each assessment method: Rx, AR (automated refraction measured with the autorefractor KR8800), WF-P (Zernike-coefficients-based objective refraction, photopic pupil size), WF-M (Zernike-coefficients-based objective refraction, mesopic pupil size), WF-4 (Zernike-coefficients-based objective refraction, 4 mm pupil), OPD-C (automated refraction measured with the aberrometer OPD in the central pupil/photopic conditions), and OPD-M (automated refraction measured with the aberrometer OPD under mesopic conditions). Results: Mean differences between ObjRx and Rx reached statistical significance for sphere and spherical equivalent (M) only with OPD-C in the POD F-GF group. All ObjRx methods showed significant differences with Rx in the POD F group, with some values differing by more than 0.50 D (-0.58 D in M for the WF-P). Bland Altman plots showed better agreement for the astigmatic components, and for sphere and spherical equivalents in both IOL groups measured with AR and OPD-M. Conclusions: None of the objective methods of refraction evaluated in this study were as reliable as the subjective refraction, irrespective of the lens material, but POD F-GF ObjRx seems to differ less with Rx than POD F ObjRx values.Award-winningPostprint (author's final draft

Clinical assessment of chromatic aberration in phakic and pseudophakic eyes using a simple autorefractor

We describe a psychophysical method and a simple setup – an autorefractor with a Scheiner disc, sequentially illuminated with red and blue lights – for the clinical assessment of the longitudinal chromatic aberration (LCA) in phakic and pseudophakic patients. This method applies to the unaccommodated eye, even in the presence of positive or negative refractive errors and astigmatism. It measures the chromatic difference of refraction as an estimate of LCA. We built a proof of concept from inexpensive and off-the-shelf optomechanical components with which we obtained the preliminary clinical results presented in the paper. We considered one control group of phakic patients and three groups of pseudophakic patients with monofocal implants of different designs and materials. The results, satisfactory and consistent with those reported by other researchers in related works, demonstrate the method and system feasibility

Representación paramétrica de la transformada de Fourier de tejidos téxtiles

Postprint (published version

Expected visual acuity and depth of focus with spherical and aspheric intraocular lenses

Trabajo presentado al 6th EOS Topical Meeting on Visual and Physiological Optics celebrado en Dublin (Irlanda) del 20 al 22 de agosto de 2012.Expected visual acuity (VA) and depth of focus (DOF) of both spheri-cal and aspheric intraocular lenses (IOLs) are calculated from the in vitro Modulation Transfer Function. The resulting VAs were similar for both types of design but DOF were larger in eyes implanted with spherical IOLs.Peer reviewe

Detection of local defects in textile webs using Gabor filters

Contiene fórmulas y gráficosA method of image analysis is proposed for detection of local defects in materials with periodic regular texture. A general improvement and enlargement of vision system capabilities for versatility, full automatism, computational efficiency, and robustness in their application to the industrial inspection of periodic textured materials is pursued. In the proposed method, a multiscale and multiorientation Gabor filter scheme that imitates the early human vision process is applied to the sample under inspection. The designed algorithm automatically segments defects from the regular texture. A variety of examples of fabric inspection are presented. In all of them defects are successfully segmented from the texture background.Supported by the Spanish CICYT under projects TAP96-1015-C03-02 and TAP97-1089 to J. Escofet, M. S. Milla´n, and J. Pladellorens, and grant TIC94- 0849 to R. Navarro.Peer reviewe

Authomatic method based on image analysis for pilling evaluation in fabrics

Contiene fórmulas, gráficos y fotografíasA fully automatic method for pilling evaluation in wear-andtear fabrics is developed from the image analysis of a set of standard photographs (Zweigle KG-741 Reutlingen). The method involves operations in both the spatial and frequency domains to segment pills from the textured background of the web. It calculates the total area of pilling in the sample image and assigns a degree of pilling according to the standard. Two mathematical descriptions are analyzed according to the underlying rule established by the standard images, using the visual estimation of the area of pilling performed by a group of observers. A logarithmic (in base two) approach, which is consistent with human visual perception laws and facilitates an optimization of the method, is eventually adopted.We acknowledge the Comisión Interministerial de Ciencia y Tecnología (CICYT), under project No. TAP97-1089.Peer reviewe

Representación paramétrica de la transformada de Fourier de tejidos textiles

La naturaleza periódica de las imágenes de tejido textil permite el uso de las técnicas de la transformación de Fourier rápida para su clasificación. Debido a los patrones de repetición dentro de las imágenes del tejido textil, es posible encontrar una forma relativamente fácil de descripción para su densidad espectral de energía. Un trabajo previamente publicado permite mostrar el uso de descriptores para el espectro de Fourier de las imágenes, en particular su eficiencia a la invarianza a la rotación, traslación y cambio de escala [1]. Dichos descriptores mostraron ser muy efectivos para representar un tejido textil y pueden ser utilizados para caracterizar texturas cuasi¿periódicas mediante técnicas no destructivas en tiempo real e in situ. Muestras de texturas textiles son evaluadas con esta técnica de representación paramétrica con el propósito de analizar su robustez y reproducibilidad. Finalmente, un conjunto de tejidos textiles es sometido a este modelo con el objetivo de evaluar la posibilidad de utilizarlo para la clasificación, verificación y reconocimiento de formas

Optical and Clinical Outcomes of an Extended Range of Vision Intraocular Lens

PURPOSE:To assess the in vitro optical quality and halo formation of the AcrySof IQ Vivity intraocular lens (IOL) (Alcon Laboratories, Inc) and to evaluate the clinical outcomes in patients who had bilateral implantation of this IOL. METHODS:The optical quality was evaluated with the PMTF optical bench (Lambda-X). Through-focus modulation transfer function area (MTFa) curves between −5.00 and +2.00 diopters (D) were obtained for 3- and 4.5-mm pupil apertures. The halo was assessed in vitro with a test bench. The clinical study included 30 patients. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity and binocular defocus curve were evaluated 6 months postoperatively. RESULTS:The through-focus MTFa curve for the 4.5-mm pupil size showed only one peak at distance focus (38.4 units). For the 3-mm pupil size, the through-focus MTFa showed a lower peak of MTFa (28.9 units), located at −0.70 D, and an extended depth of focus up to −2.20 D. The halo formed was larger and more intense compared to a standard monofocal IOL. The clinical outcomes at 6 months revealed satisfactory visual acuity outcomes. All patients achieved a binocular CDVA of 0.1 logMAR or better. The mean visual acuity was better than 0.2 logMAR between +1.00 and −2.00 D of defocus. At a vergence of −2.50 D, the visual acuity was 0.31 ± 0.09 logMAR. CONCLUSIONS:The AcrySof IQ Vivity IOL provided good distance optical and visual quality and an extended range of focus of approximately 2.00 D, obtaining an optimal or functional visual acuity up to 50 to 40 cm. The halo formed was low intensity overall, but higher intensity than a monofocal IOL