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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.

iii) Results. The results show that the green, brown and blue filters, do not cause significant changes in contrast sensitivity when compared with a grey filter of equal luminance, although chromatic discrimination is disturbed. Yellow and orange filters improve achromatic contrast at certain spatial frequencies, but impair chromatic discrimination. iv) Conclusions. Compared to grey 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 tritanlike defects with discrimination losses increasing with the cut-off wavelength.

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Purpose To analyze the “in vitro” aberrometric pattern of a refractive IOL and two extended depth of focus IOLs. Methods A special optical bench with a Shack-Hartmann wavefront sensor (SH) was designed for the measurement. Three presbyopia correction IOLs were analyzed: Mini WELL (MW), TECNIS Symfony ZXR00 (SYM), and Lentis Mplus X LS-313 MF30 (MP). Three different pupil sizes were used for the comparison: 3, 4, and 4.7 mm. Results MW generated negative primary and positive secondary spherical aberrations (SA) for the apertures of 3 mm (−0.13 and +0.12 μm), 4 mm (−0.12 and +0.08 μm), and 4.7 mm (−0.11 and +0.08 μm), while the SYM only generated negative primary SA for 4 and 4.7 mm apertures (−0.12 μm and −0.20 μm, resp.). The MP induced coma and trefoil for all pupils and showed significant HOAs for apertures of 4 and 4.7 mm. Conclusions In an optical bench, the MW induces negative primary and positive secondary SA for all pupils. The SYM aberrations seem to be pupil dependent; it does not produce negative primary SA for 3 mm but increases for higher pupils. Meanwhile, the HOAs for the MW and SYM were not significant. The MP showed in all cases the highest HOAs.

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.

The use of a single value of nk for the calculation of the total corneal power in keratoconus has been shown to be imprecise, leading to inaccuracies in the detection and classification of this corneal condition. Furthermore, our study shows the relevance of corneal thickness in corneal power calculations in keratoconus.

We have compared corresponding pairs obtained by simultaneous matching (haploscopic matching) and by memory matching (after 10 minutes) using 34 reference tests selected from the Munsell Atlas (glossy) belonging to the four main hues 5Y, 5G, 5PB and 5RP. These colours lie very close to the F 1 and F 2 axis in the SVF space, where we have analysed our results. Illuminants D 65 and A were used as reference and matching illuminants, respectively. Our results show, for both kinds of matching, a tendency to select more colourful colours than the original ones, with significant differences between matching and test colours, whereas hue does not seem to follow a definite pattern. This behaviour is similar to that found in colour matching experiments without illuminant changes. The analogy does not hold for lightness, which in the present experiment does not seem to follow a clear pattern. The best matching colours lie along the red-green axis and the worst matching colours along the blue-yellow axis.