Search

In this study, effects of smoking on colour vision with the Farnsworth–Munsell 100 Hue test (FM100h) and achromatic (A), red-green (RG), and blue-yellow (BY) contrast sensitivity functions were evaluated. In total, 50 non-smoker controls and 25 smokers, divided into two groups (group 1, less than 10 cigarettes per day, with 15 patients, and group 2, >10 cigarettes per day, with 10 patients) took part in the experiments. Best-corrected visual acuity (BCVA), FM100h, and A, RG, and BY contrast sensitivity functions were measured. Total and partial RG and BY error scores (TES and PTES) and colour axis index (CA) were used in the analysis. No differences between smoker and non-smoker groups were found in BCVA, CA and A and BY contrast sensitivity, but TES and PTES values and RG contrast sensitivity at 1 cpd were statistically different. Differences between smoker groups were not significant. Error scores in smokers were positively correlated with the number of cigarettes smoked per day, and in BY also with age. Tobacco caused discrimination losses in both chromatic mechanisms but affected the red-green pathway more than the blue-yellow, and therefore, a partial RG score of FM100h test seems to be a good predictor of smoker colour deficiencies.

Producción Científica, The easy access to electronic devices for users has resulted in the development of a vast range of programs and applications for visual evaluation and diagnosis that can be downloaded to any device. Some of them are based on tasks and stimuli that depend on luminance. The aim of the present study was to evaluate differences in luminance reproduction between electronic devices and their implications for contrast reproduction. A total of 20 Galaxy Tab A devices with 8-bit graphics processing units were evaluated. Characterization of every screen was performed obtaining the response curve for the achromatic stimulus. Mean, maximum and minimum luminance, standard deviation and coefficient of variation were obtained to assess differences between devices. Variation of luminance with increasing digital level was observed in all devices following a gamma distribution. Comparison between devices for mean results showed that some of them differed by as much as 45 cd/m2. The coefficient of variation varied from ~5 to 9%. Mean percentage of differences in luminance between devices reached 30%. In conclusion, differences in luminance reproduction between devices were present, even considering devices from the same manufacturing batch. It cannot be assumed that the characterization of one device can be extrapolated to other devices. Every device used for research purposes should be individually characterized to ensure the correct reproduction. For clinical purposes, limitations should be considered by visual specialists., Ministerio de Economía, Industria y Competitividad - program Ramón y Cajal (RYC-2016-20471), Centro para el Desarrollo Tecnológico Industrial y el Fondo Europeo de Desarrollo Regional (IDI-20180123)

Producción Científica, The authors of this study evaluated the potential benefit on visual performance of a novel 3 week visual rehabilitation program based on the use of Gabor patches in patients undergoing bilateral cataract surgery with the implantation of two models of trifocal diffractive intraocular lens (IOL). A total of 30 patients were randomly assigned to two groups: a study group (15 patients) that used a videogame based on Gabor patches and a placebo group (15 patients) that used a videogame without specific stimuli for improving visual performance. No statistically significant differences between groups were found in distance, intermediate, and near post-training visual acuity (p ≥ 0.15). Significantly better distance contrast sensitivity (CS) was found for the spatial frequencies of 6 (p = 0.02) and 12 cpd (p = 0.01) in the study group. Likewise, significantly better values of near CS were found in the study group compared to the placebo group for the spatial frequency of 1.5 cpd (p = 0.02). In conclusion, a 3 week visual rehabilitation program based on the use of Gabor patches in the immediate postoperative period after the bilateral implantation of trifocal diffractive IOLs seems to be beneficial for improving both distance and near visual performance achieved with the implant, Ministerio de Economía, Industria y Competitividad - FEDER (EXP 00106153/IDI-20180123), Ministerio de Economía, Industria y Competitividad - program Ramón y Cajal (RYC-2016-20471)

To analyze using optical simulations if the proper use of a segmented intraocular lens (IOL) can improve the visual outcomes compared to the implantation of a spherical monofocal IOL. The wavefront profile of the Mplus (Oculentis) and a monofocal IOLs with the phase transformation introduced by each IOL were calculated using a Hartmann-Shack wavefront sensor. In addition, the wavefront profile of schematic eye models of various keratoconus conditions was obtained and was propagated to the IOLs. The optical performance of such combination was obtained after combining ray tracing and Fourier optics. A pre-clinical validation was also evaluated incorporating clinical data from three different keratoconus eyes of three patients. The implantation of the Mplus IOL can compensate or reduce the overall coma of the eye with keratoconus improving the quality of vision compared with a spherical monofocal IOL due to lower displacements of the retinal image or tilting in keratoconus. All theoretical simulations were confirmed afterwards by mean of a preclinical validation. The use of a standard toric segmented IOL with a proper orientation and selection of the addition can improve the optical quality of the keratoconus eye compared to the use of a monofocal spherical IOL. David P. Piñero is supported by the Spanish Ministry of Economy, Industry and Competitiveness within the program Ramón y Cajal, RYC-2016-20471.

In recent years, virtual reality (VR) has emerged as a new safe and effective tool for neurorehabilitation of different childhood and adulthood conditions. VR-based therapies can induce cortical reorganization and promote the activation of different neuronal connections over a wide range of ages, leading to contrasted improvements in motor and functional skills. The use of VR for the visual rehabilitation in amblyopia has been investigated in the last years, with the potential of using serious games combining perceptual learning and dichoptic stimulation. This combination of technologies allows the clinician to measure, treat, and control changes in interocular suppression, which is one of the factors leading to cortical alterations in amblyopia. Several clinical researches on this issue have been conducted, showing the potential of promoting visual acuity, contrast sensitivity, and stereopsis improvement. Indeed, several systems have been evaluated for amblyopia treatment including the use of different commercially available types of head mounted displays (HMDs). These HMDs are mostly well tolerated by patients during short exposures and do not cause significant long-term side effects, although their use has been occasionally associated with some visual discomfort and other complications in certain types of subjects. More studies are needed to confirm these promising therapies in controlled randomized clinical trials, with special emphasis on the definition of the most adequate planning for obtaining an effective recovery of the visual and binocular function. All authors have been supported by CDTI (Centro para el Desarrollo Tecnológico Industrial, Ministry of Economy and Competitiveness of Spain) by means of the PID program (Proyectos de Investigación y Desarrollo) in the context of the Project NEIVATECH (Neuroplasticity through Virtual Reality for Amblyopia) (application number: 111705). David P. Piñero was supported by the Ministry of Economy, Industry and Competitiveness of Spain, through the program Ramón y Cajal, RYC-2016-20471.

Background The measurement of the pupillary function is an indispensable test in some eye examinations, being necessary the evaluation of the precision of instruments performing such measures. The aim of this study was to evaluate the intrasession repeatability of pupil size measurements provided by a multidiagnostic platform in a large sample of healthy eyes. Methods This prospective study enrolled 100 healthy eyes of 100 patients, with ages ranging from 23 to 65 years old. Repeated pupil size measures under photopic (P, 220 lx), mesopic (M, 160 lx), low mesopic (L, 70 lx), and scotopic conditions (S, 1 lx) were obtained with the VX120 system (Visionix-Luneau Technologies, Chartres, France) after a complete eye exam. Likewise, pupil size was also measured once in the fellow eye in a total of 75 eyes. The level of intrasession variability as well as differences between fellow eyes were evaluated. Results Most of differences between repeated measures did not exceed 0.5 mm (82% of S and 100% of P below this value). No significant differences between these repeated measures were found for S (p = 0.099) and L (p = 0.751). However, statistically significant differences were found between repeated measures for M (p = 0.002) and P (p = 0.003). The analysis of clinical relevance of differences between pairs (Passing-Bablok) only confirmed the clinical relevance of differences between the first and second repeated measurement of M. Concerning the comparative analysis between fellow eyes, no statistically significant differences in pupil size were found between right and left eyes in any light condition evaluated (p ≥ 0.227). Conclusions The VX120 system can provide consistent measurements of pupil size under scotopic, low mesopic and photopic conditions, with a relative limitation under mesopic conditions.

The push-up method is routinely used to measure the amplitude of accommodation. In this method the diopter value corresponding to the nearest point that the eye can focus is determined, wearing his neutralizing lens, but not the value of the maximum diopter variation that makes the eye. The aim of this paper is to review the calculation described in the push-up method taking into account the real position of the near point of the eye. In the subjective push-up method, it is calculated the reciprocal of the distance from the lens until the test object at this position of first, slight, sustained blur. We calculated the differences between this value and the ocular amplitude of accommodation, taking into account that the eye is really looking at the image of first blur through the neutralizing lens. Experimental measurements were also taken to determine whether they were similar to theoretical values. The results obtained by the two calculation methods compared were in general significantly different and the difference was greater for young people with high ametropy. The theoretical results were in agreement with the experimental ones. According to the optometric information required must select the appropriate calculation method, since the values obtained in each of them are not comparable.

Video projectors allow interesting applications in vision sciences since they provide a large projection area. We have colorimetrically characterized a LCoS projector using a mathematical model requiring additivity and constancy of the primaries -a sigmoid function in our case. Significant differences in chromaticity in the CIELAB space, but not in lightness, were found between the center and the corners of the screen. The lack of spatial homogeneity led us to estimate the parameters of the model as a function of spatial position, using different strategies. The best result was obtained by interpolating the values of the parameters of the model determined from experimental measurements in a regular spatial grid on the screen.

Purpose: To develop and validate a new iPad-based color vision test (Optopad). Methods: A total of 341 student eyes were enrolled in a first comparative study between Optopad and the Isihara tests. In a second comparative study, Optopad vs. the Farnworth-Munsell test (FM 100H), a total of 66 adult eyes were included. Besides the agreement between tests, the correlation between FM 100H and Optopad outcomes were investigated. Multiple regression analysis was used to predict the total error score (TES) from contrast thresholds measured with the Optopad test. Results: The Ishihara and Optopad tests detected the same anomalous patients. Concerning FM 100H vs. Optopad, 10 subjects were diagnosed as anomalous with both tests, 3 mild anomalous cases based on TES were classified as normal with Optopad, and 2 anomalous subjects based on Optopad test showed normal TES values. Statistically significant correlations of TES and partial error red-green (PTESRG) with thresholds measured with the red-green Optopad stimuli were found. A multiple quadratic regression model was obtained relating TES and chromatic contrast values from Optopad (R2 = 0.855), with only 13 cases showing residuals of ≥ 25 units. Conclusions: The design and implementation of a chromatic contrast discrimination test has been carried out, with promising clinical results. This test seems to provide comparable outcomes to those obtained with Ishihara and FM 100H tests.

Purpose: To evaluate a new method of calculation of total corneal astigmatism based on Gaussian optics and the power design of a spherocylindrical lens (C) in the healthy eye and to compare it with keratometric (K) and power vector (PV) methods. Methods: A total of 92 healthy eyes of 92 patients (age, 17–65 years) were enrolled. Corneal astigmatism was calculated in all cases using K, PV, and our new approach C that considers the contribution of corneal thickness. An evaluation of the interchangeability of our new approach with the other 2 methods was performed using Bland–Altman analysis. Results: Statistically significant differences between methods were found in the magnitude of astigmatism (P < 0.001), with the highest values provided by K. These differences in the magnitude of astigmatism were clinically relevant when K and C were compared [limits of agreement (LoA), −0.40 to 0.62 D), but not for the comparison between PV and C (LoA, −0.03 to 0.01 D). Differences in the axis of astigmatism between methods did not reach statistical significance (P = 0.408). However, they were clinically relevant when comparing K and C (LoA, −5.48 to 15.68 degrees) but not for the comparison between PV and C (LoA, −1.68 to 1.42 degrees). Conclusions: The use of our new approach for the calculation of total corneal astigmatism provides astigmatic results comparable to the PV method, which suggests that the effect of pachymetry on total corneal astigmatism is minimal in healthy eyes.

SIGNIFICANCE: Apple devices could be suitable for vision tests, provided that the test has been correctly adapted to the device, after considering the spatial and colorimetric characterization of the screen. PURPOSE: The majority of vision applications has not been developed by vision or colorimetry experts and suffers from conceptual and design errors that may lead average users to an erroneous assessment of their visual capabilities. The reliability of vision tests depends on the accurate generation of the necessary visual stimuli in a particular device. Our aim was to ascertain whether a given color test, designed for a colorimetrically characterized device, might be used in another similar device. METHODS: We evaluated color reproduction errors in three iPad tablets of different models with Retina screens, using their individual color characterization models and the model derived for another device. RESULTS: Our results showed, even with this small sample, the high degree of error caused when disregarding the fact that the colorimetric design valid for a given device may not be correct when displayed in another. CONCLUSIONS: The distortion of the chromatic content may lead to subjects with vision defects to pass as normal or vice versa, compromising diagnosis reliability.

Background: In this study, the reliability of perimetric contrast sensitivity measurements favouring the achromatic, the red-green and the blue-yellow post-receptorial mechanisms was analysed. Methods: A new technique, multichannel ATD perimetry, provides spatial and temporal stimuli favouring the detection by an achromatic mechanism (A), from a magno or parvocellular origin or by a red-green (RG) chromatic mechanism, with a parvocellular origin or a blue-yellow (BY) mechanism, with a koniocellular origin. The repeatability and reproducibility of contrast sensitivity measurements with these stimuli were studied in a group of 40 healthy subjects. The analysis was carried out on 21 testing points within a 60° by 40° fovea-centred region of the visual field. Results: The within-observer repeatability for the four mechanisms studied is either good or excellent when the intra-class correlation coefficient (ICC) can be calculated. For the remaining points, the Friedman's test finds that the measurements are repeatable. The between-observer reproducibility was either excellent or good in cases where the ICC was applied and according to the Friedman's test all results were reproducible. Conclusions: The results obtained showed good repeatability and reproducibility with A, RG and BY stimuli, although with BY stimuli repeatability is slightly worse. Future studies on the diagnostic validity of this device are based on the fact that changes of sensitivity can be compared by means of a visual single task, contrast sensitivity measurement and using a common metric. The ATD multichannel perimeter was built thanks to the support of the Spanish Ministerio de Ciencia y Tecnología Grants DPI2000-0116-P4-02 and PTR 1995-0909-OP, in collaboration with INDUSTRIAS DE OPTICA SA (San Cugat del Vallés, Spain).

Purpose. To evaluate the intrasession repeatability of corneal curvature, eccentricity, and aberrometric measurements obtained with a multidiagnostic device in healthy eyes.Methods. This study enrolled 107 eyes of 107 patients ranging in age from 23 to 65 years. All of them underwent a complete anterior segment examination with the VX120 system (Visionix-Luneau Technologies, Chartres, France). Three consecutive measurements were obtained. The within-subject standard deviation (Sw), intrasubject precision (1.96×Sw), and intraclass correlation coefficient (ICC) were calculated.Results. AllSwfor corneal power measurements were below 0.26 D, with ICC above 0.982. TheSwfor corneal astigmatism at different areas (3, 5, and 7 mm) was below 0.21 D, with ICC above 0.913. Concerning the axis of astigmatism, itsSwwas below 11.27°, with ICC above 0.975. TheSwand ICC for corneal eccentricity were 0.067 and 0.957, respectively. TheSwand ICC for high-order aberration root mean square (RMS) were 0.048 µm and 0.901, respectively. For 3rd- and 4th-order aberrometric parameters, allSwwere below 0.037 µm and all ICC were higher than 0.84, except for quadrafoil RMS (ICC: 0.689).Conclusions. The multidiagnostic device evaluated is able to provide consistent measurements of corneal power, eccentricity, and third- and fourth-order aberrations in healthy eyes.

David P Piñero,1 Alberto López-Navarro,2 Inmaculada Cabezos,1 Dolores de Fez,1 María T Caballero,1 Vicent J Camps1 1Group of Optics and Visual Perception, Department of Optics, Pharmacology and Anatomy, University of Alicante, 2Optometry Clinic, Prevention Service of the University of Alicante, Alicante, Spain Purpose: To evaluate the intrasession repeatability of refractive and ocular aberrometric measurements obtained using a new multidiagnostic device in healthy eyes.Patients and methods: A total of 107 eyes of 107 patients, age ranging from 23 to 65years, were enrolled in this study. A complete eye examination was performed in all eyes, including an ocular examination using the VX120 system. Three consecutive measurements were obtained using this device to assess the intrasession repeatability of different refractive and ocular aberrometric parameters. The within-subject standard deviation (Sw), intrasubject precision (1.96×Sw), and intraclass correlation coefficient (ICC) were calculated.Results: Sw and intrasubject precision for refractive data were below 0.12 and 0.20D, respectively, in all cases. The ICC ranged from 0.947 for the J45 power vector component to 0.997 for the sphere. Concerning aberrometric measurements Sw and intrasubject precision values were below 0.05µm and 0.10µm, respectively. Likewise, the ICC ranged from 0.805 for the quadrafoil root mean square to 0.954 for the primary spherical aberration. Poor correlations were found between most of the refractive parameters and their Sw (–0.033≤r≤0.053, p≥0.064). Moderate and significant positive correlations were found between the magnitude of the aberrometric parameters evaluated and their Sw (r≥0.446, p

espanolEn el presente estudio se ha disenado y testeado un campimetro de deteccion de anomalias en la percepcion cromatica utilizando un proyector de video (Multicampimetro). Para ello se ha caracterizado colorimetricamente un proyector de video, pixel a pixel, intentando modelizar las inhomogeneidades de la proyeccion. Se han determinado los valores triestimulo de los primarios del proyector, en funcion del nivel digital, en 49 localizaciones de la superficie de proyeccion y, a partir de ellas, se ha llegado a un modelo de caracterizacion del dispositivo que minimiza las diferencias de color entre el color predicho y el reproducido, en comparacion con el metodo tradicional, que generaliza la caracterizacion del centro a toda la pantalla. Con este perimetro, hemos medido los umbrales de deteccion de estimulos que favorecen la respuesta de los mecanismos cromaticos (rojo-verde y azul-amarillo) del sistema visual humano, utilizando dos configuraciones de tamano: tamano constante y tamano variable con la excentricidad y adaptado a los campos receptivos del cortex visual. El metodo psicofisico de medida utilizado es el MOBS (Modified Binary Search). Se han estudiado los parametros que pueden influir en la distorsion de la medida, asi como la repetitividad, la especificidad y la sensibilidad del dispositivo, resultando favorables estos tres ultimos parametros. Se ha creado una base de datos para la configuracion de estimulo a tamano constante y se ha comprobado que los resultados de la sensibilidad de ambos mecanismos reproducen las caracteristicas ya descritas en la bibliografia. Al comparar ambas configuraciones de tamano, se encuentra mayor sensibilidad periferica y mejor repetitividad con el estimulo de tamano adaptado a la excentricidad. EnglishIn the present study, we have designed and tested a perimeter for the detection of damage in the chromatic mechanisms using a video projector. To this purpose, we have characterized pixel to pixel a video projector, to account for the inhomogeneities in the projection. We have measured the tristimulus values of the projector primaries as a function of digital level, at 49 locations of the projection screen and, from them, we have arrived to a characterization model which reduces the color differences between predicted and reproduced color, in comparison with the traditional method, which generalizes the characterization of the screen center to all the screen. With the perimeter, we measured the detection thresholds of stimuli favouring the response of the red-green and blue-yellow chromatic mechanisms of the human visual system. Stimulus size could either be constant or change with eccentricity with the size of the receptive fields of the neurons in the visual cortex. The psychophysical method of measurement used is the MOBS (Modified Binary Search). We have studied the factors that can distort the measurements, as well as the repeatability, the specificity and the sensitivity of the device, with good results. A database has been created for the configuration of constant size stimulus. The trends shown by the data are consistent with the literature. When comparing both size configurations, the peripheral sensitivity is increased and repeatability is better with the stimulus size adapted to the eccentricity.

The measurement of accommodative response is usually performed by means of the Nott method. The accommodative response values were obtained as described in the bibliography and considering that the neutralizing lens shapes the target image. The values in accommodative response differ according to the calculation method utilized. The accommodation and convergence values when the target is placed 40 cm away from the glasses are not the same in emmetropic and ametropic subjects. At the position of the effective binocular object, the initial values are indeed the same for both types of subjects. Comparing with experimental measurements using the Monocular Estimate Method (Mem), it was obtained the same values given the effect of the neutralizing lens. Optimizing the Nott method would require placing the target at a position where the effective binocular object is 40 cm. Furthermore, the effect of the neutralizing lens should be considered in the calculation method.

Status of binocular vision is evaluated using binoculars and accommodative tests. The results of these tests allow the optometrist to decide or the type of lenses has to be prescribed or whether a vision therapy is required. The aim of this work is to check the accuracy of the measurement of the relative amplitude of accommodation. Relative accommodation amplitude assesses the ability to increase or decrease the accommodation when convergence demand is constant. The eye must be neutralized to take the measurement. Because the test is situated at a distance of 40 cm, it is considered that the convergence is 2'5 am and the accommodation 2'50 D. However, this assumption could lead to important errors in ammetropic subjects due to the eye after neutralization accommodates in the image produced by the lens forms and converges in the position of the effective binocular object [1]. Therefore, it is necessary to set measurement conditions in which the accommodative and convergence stimulus are the same for all subjects. Furthermore, the lenses added on the neutralization to determine the relative amplitude of accommodation do not correspond to the dioptric value of relaxation and stimulation of the eye accommodation. To obtain this value a more precise calculation has to be performed.

We have designed a configurable stand-alone Matlab-based software to simulate dichromatic perception of video streams. The algorithm used is an extension for video streams of the “corresponding pair algorithm” by Capilla and coworkers for simulation of dichromatic perception of images. The software allows the user to upload a video sequence and to process it using different dichromatic color vision models and viewing conditions. The output video may be generated in different spatial and temporal resolutions and file formats. The functions for Matlab environment and a stand-alone application may be downloaded from the Repository of the University of Alicante. © 2013 Wiley Periodicals, Inc. Col Res Appl, 39, 486–491, 2014

This study aimed to evaluate the theoretical influence on intraocular lens power (PIOL) calculation of the use of keratometric approach for corneal power (Pc) calculation in keratoconus and to develop and validate an algorithm preliminarily to minimize this influence. Methods: Pcwas calculated theoretically with the classical keratometric approach, the Gaussian equation, and the keratometric approach using a variable keratometric index (nkadj) dependent on r1c(Pkadj). Differences in PIOL calculations (ΔPIOL) using keratometric and Gaussian Pcvalues were evaluated. Preliminary clinical validation of a PIOLalgorithm using Pkadj was performed in 13 keratoconus eyes. Results: PIOL underestimation was present if Pc was overestimated, and vice versa. Theoretical PIOLoverestimation up to −5.6 D and −6.2 D using Le Grand and Gullstrand eye models was found for a keratometric index of 1.3375. If nkadjwas used, maximal Δ PIOL was ±1.1 D, with most of the values ≤±0.6 D. Clinically, PIOLunder- and over-estimations ranged from −1.1 to − 0.4 D. No statistically significant differences were found between PIOL obtained with Pkadjand Gaussian equation (P > 0.05). Conclusion: The use of the keratometric Pcfor PIOL calculations in keratoconus can lead to significant errors that may be minimized using a Pkadj approach. The research leading to these results has received funding from the Generalitat Valenciana (Valencian Community, Spain) under the grant for emergent research groups with reference GV2014/086.

To obtain an accurate algorithm for calculating the keratometric index that minimizes the errors in the calculation of corneal power assuming only a single corneal surface in the range of corneal curvatures of the normal population.Corneal power was calculated by using the classical keratometric index and also by using the Gaussian equation. Differences between types of calculation of corneal power were determined and modeled by regression analysis.We proposed two options for the selection of the most appropriate keratometric index (n(k)) value for each specific case. First was the use of specific linear equations (depending on the ratio of the anterior to the posterior curvature, k ratio) according to the value of the central radius of curvature of the anterior corneal surface (r(1c)) in 0.1 mm steps and the theoretical eye model considered. The second was the use of a general simplified equation only requiring r(1c) (Gullstrand eye model, n(k) = -0.0064286r(1c) + 1.37688; Le Grand eye model, n(k) = -0.0063804r(1c) + 1.37806).The generalization of the keratometric index (n(k)) value is not an appropriate approximation for the estimation of the corneal power and it can lead to significant errors. We proposed a new algorithm depending on r(1c), with a maximal associated error in the calculation of the corneal power of 0.5 D and without requiring knowledge of the posterior corneal curvature.

This work uses the S-CIELAB color model to compare images that have been calibrated and processed using a colorimetric dithering method which simulates increments in viewing distance. Firstly, we obtain XYZ calibrated images by applying the appropriate color transformations to the original images. These transformations depend on whether the image is viewed on a display device or encoded by a capture device, for example. Secondly, we use a colorimetric dithering method consisting of a partitive additive mixing of XYZ tristimulus values. The number of dithered pixels depends on simulated viewing distance. The dithered tristimulus values are transformed to digital data to observe the dithering effects in the image. Finally, we predict color differences using the S-CIELAB model as color appearance model for images. Moreover, this paper proposes some applications of this method to artistic and industrial problems where one must compare two images that appear different at close viewing distance, but match when they are seen from afar.

In this work, the metric of a new multistage colour vision model, ATTD05, is assessed and a new colour difference formula is suggested. Firstly, the uniformity of the ATTD05 colour space was compared with that of CIECAM02 for some Munsell samples, because if the model yields a uniform perceptual space, we will be able to implement a colour difference formula as a Euclidian distance between two points. Secondly, we developed a new space based on the perceptual descriptors of the model: brightness, hue, colourfulness, and saturation. After that, we calculated the free parameters of the space that better fit the measured and experimental data of two datasets (small-magnitude and large-magnitude colour differences), by minimizing the performance factor (PF/3). Finally, we compare colour differences calculated for ATTD05 and for other models. The PF/3 and the STRESS parameters were used to decide which model predicts better perceptual differences and, therefore, which model was the more uniform. Spanish Ministry for Education and Science; contract grant numbers: DPI2005-08999-C02-02 and DPI2008-06455-C02-02.

We present a systematic algorithm capable of searching for optimal colors for any lightness L* (between 0 and 100), any illuminant (D65, F2, F7, F11, etc.), and any light source reported by CIE. Color solids are graphed in some color spaces (CIELAB, SVF, DIN99d, and CIECAM02) by horizontal (constant lightness) and transversal (constant hue angle) sections. Color solids plotted in DIN99d and CIECAM02 color spaces look more spherical or homogeneous than the ones plotted in CIELAB and SVF color spaces. Depending on the spectrum of the light source or illuminant, the shape of its color solid and its content (variety of distinguishable colors, with or without color correspondence) change drastically, particularly with sources whose spectrum is discontinuous and/or very peaked, with correlated color temperature lower than 5500 K. This could be used to propose an absolute colorimetric quality index for light sources comparing the volumes of their gamuts, in a uniform color space. This research was supported by the Ministerio de Educación y Ciencia, Spain, under grant DPI2005-08999-C02-02, and by the Conselleria d’Empresa, Universitat i Ciència of the Generalitat Valenciana, Spain, under grant IIARC0/2004/59.

The Department of Optics of the University of Alicante is organizing a one-year (2005-6 period) postgraduate course in colour technology with the collaboration of members of the academic staff of several Spanish universities (University of Granada, Technical University of Catalonia, Technical University of Valencia, University of Valencia, etc) and other national institutions (CSIC's Department of Metrology and Technological Institute of Optics, Colour and Imaging-AIDO). Several multinational companies have also shown their interest in collaborating. We wish this course to mark the beginning of multi-disciplinary and inter-universities national postgraduate studies, with a high degree of professional specialisation, which fulfil the guidelines of the European Higher Education Area (Bologna Process) and other European technological platforms such as Manufuture or EuMaT.

Purpose. Tinted lenses for everyday use should not impair visual acuity and contrast sensitivity or cause radical changes in color perception. The main aim of this study was to compare the performance in contrast detection and color discrimination tasks of a set of tinted lenses with that of gray filters of equal luminance under D65. Methods. The contrast sensitivity functions of 10 observers were measured using sinusoidal gratings of mean luminance of 13 cd/m 2 by the adjustment method. Color discrimination thresholds from white (x 0.313, y 0.330), green (x 0.346, y 0.407), and blue (x 0.280, y 0.253) were measured along 12 directions in the CIE-1931 xy diagram with and without lenses. Results. Green, brown, and blue filters did not cause significant changes in contrast sensitivity compared with a gray filter of equal luminance, although chromatic discrimination was disturbed. Yellow and orange filters improved achromatic contrast at certain spatial frequencies, but impaired chromatic discrimination. Conclusions. Compared with gray filters of the same luminance, yellow filters may be useful when enhancement of low achromatic contrasts is desirable, although overall brightness decrements may occur. Nevertheless, these lenses cause tritan-like defects with discrimination losses increasing with the cutoff wavelength. (Optom Vis Sci 2002;79:-)

Purpose: In this study, we describe contrast sensitivity losses in the visual field of a patient affected by chloroquine toxicity, measured with stimuli favoring different visual mechanisms. We have compared these results with those of other, usual clinical tests. Methods: The vision of a patient who underwent ten years of chloroquine treatment was analyzed by a battery of clinical tests: visual acuity (VA), Amsler’s grid, Farnsworth–Munsell 100-hue test, spectral domain optical coherence tomography, multifocal electroretinogram (ERG), white-on-white and red-on-white Humphrey perimetries, chromatic and achromatic contrast sensitivity perimetry tests, and fluorescein angiography. Measurements were taken just before the cessation of the treatment, and 6 months later. Results: The subjective visual perception of the patient was worse (in comparison with the rest of the visual field at the time of the first visit) in the center of the visual field, and was impaired on the second visit. Although standard automated perimetry (SAP) was practically normal and ERG results did not worsen with time, VA, Amsler’s grid, and visual fields with stimuli favoring the magnocellular and chromatic pathways signalled progressive loss of visual function. Conclusions: Standard tests such as SAP or ERG may not detect visual field losses or progression of existing visual losses in a case of chloroquine toxicity, whereas tests evaluating contrast sensitivity with stimuli favoring different visual mechanisms may be more sensitive. The ATD multichannel perimeter was built thanks to the support of the Spanish Ministerio de Ciencia y Tecnología (Grants DPI2000-0116-P4-02 and PTR 1995-0909-OP), in collaboration with Industrius De Optica SA (San Cugat del Vallés, Spain).