Metasurface-based contact lenses for color vision deficiency.

We embed large-scale, plasmonic metasurfaces into off-the-shelf rigid gas permeable contact lenses and study their ability to serve as visual aids for color vision deficiency. In this study, we specifically address deuteranomaly, which is the most common class of color vision deficiency. This condition is caused by a redshift of the medium-type cone photoreceptor and leads to ambiguity in the color perception of red and green and their combinations. The effect of the metasurface-based contact lenses on the color perception was simulated using Commission Internationale de l'Eclairage (CIE) color spaces and conventional models of the human color-sensitive photoreceptors. Comparison between normal color vision and uncorrected and corrected deuteranomaly by the proposed element demonstrates the ability offered by the nanostructured contact lens to shift back incorrectly perceived pigments closer to the original pigments. The maximal improvement in the color perception error before and after the proposed correction for deuteranomaly is up to a factor of $\sim{10}$∼10. In addition, an Ishihara-based color test was also simulated, showing the contrast restoration achieved by the element, for deuteranomaly conditions.

Clinical spectrum of AIFM1-associated disease in an Irish family, from mild neuropathy to severe cerebellar ataxia with colour blindness.

Mutations in apoptosis-inducing factor mitochondrion-associated-1 (AIFM1) cause X-linked peripheral neuropathy (Cowchock syndrome, CMT4X); however, more recently a cerebellar presentation has been described. We describe a large Irish family with seven affected males. They presented with a variable age of onset, 18 months to 39 years of age. All developed variably present sensorineural deafness, peripheral neuropathy, cerebellar ataxia, and pyramidal involvement. In addition, three had colour vision deficiency. Scale for the assessment and rating of ataxia ranged 2 to 23/40, while Charcot-Marie-Tooth neuropathy score 2 varied between 7 and 13/36. All individuals had normal cognitive assessment. Neurophysiology demonstrated length-dependent large-fibre sensorimotor axonal neuropathy, with particular involvement of superficial radial sensory responses. Brain imaging, performed in four, revealed varying extent of cerebellar atrophy, and white matter changes in one. Optical coherence tomography was abnormal in one, who had unrelated eye pathology. Four obligate female carriers were assessed clinically, two of them neurophysiologically; all were unaffected. Whole genome sequencing demonstrated a previously reported hemizygous AIFM1 mutation. Analysis for mutations in other genes associated with colour deficiency was negative. AIFM1-associated phenotype in this family demonstrated significant variability. To our knowledge, this is the first report of AIFM1-associated colour blindness. Superficial radial nerve was particularly affected neurophysiologically, which could represent a phenotypic marker towards this specific genetic diagnosis.

Do Type 1 Diabetes Mellitus and Color-Vision Deficiencies Influence Shade-Matching Ability?

PURPOSE: To evaluate the effect of color-vision deficiencies and type 1 diabetes mellitus (DM) on visual shade-matching ability. MATERIALS AND METHODS: Four groups of participants were investigated: a control group (n = 68); a group with protanomalia (n = 10); a group with deuteranomalia (n = 19); and a group with type 1 DM (n = 13). Color vision was evaluated monocularly using the Ishihara test, Farnsworth-Munsell 100 hue (FM100H) test, Hardy Rand Rittler (HRR) test, and with an HMC Anomaloskop MR (Rayleigh and Moreland tests). The final exam was on a Toothguide Training Box (TTB) and consisted of 15 lightness-chroma-hue tasks. The color difference (ΔE*ab) and the shade-matching score (ΣΔE*ab) were computed, and the correct lightness (L*), chroma (C*), and hue (h*) selections were counted. The means and standard deviations for the ΣΔE*ab, ΔE*ab, L*, C*, h*, Ishihara, HRR, FM100H, and Rayleigh and Moreland tests were calculated. One-way analysis of variance (ANOVA) and post hoc Bonferroni test were used for statistical analyses and a comparison of means (α = .05). The data analyses were performed using SPSS 22.0 for Windows (IBM). RESULTS: The control group selected the shade tab on the TTB significantly better (ΣΔE*ab = 31.57 ± 13.50) than the group with protanomalia (ΣΔE*ab = 55.50 ± 12.36; P < .0001) and the group with deuteranomalia (ΣΔE*ab = 59.18 ± 16.35; P < .0001), but not significantly better than the group with type 1 DM (ΣΔE*ab = 39.43 ± 11.46; P = .368). The group with type 1 DM selected the shade tab on the TTB significantly better than the group with protanomalia (P = .038) and the group with deuteranomalia (P < .0001). CONCLUSION: Participants with color-vision deficiencies are less accurate at shade matching than the control group and the group with type 1 DM.

AcrySof Natural SN60AT versus AcrySof SA60AT intraocular lens in patients with color vision defects.

PURPOSE: To determine whether implantation of the AcrySof Natural intraocular lens (IOL) worsened the severity of existing color deficit in congenital partial red-green color deficient individuals (CPRG). METHODS: A prospective controlled randomized double-masked analysis of 30 consecutive patients with CPRG defect and bilateral cataracts received a Natural IOL (test group) in 1 eye and a single-piece AcrySof IOL (control group) in the other eye. Patients were tested unilaterally to detect CPRG defect using Ishihara pseudoisochromatic plates and the Farnsworth D-15 test. Plates 1 to 21 measured the Ishihara error score; plates 22 to 25 indicated severity of defect based on clarity of both numerals as partial mild/moderate (both visible), partial severe defect (only 1 visible). The D-15 test is based on number of diametrical crossings on the circular diagram; severity is graded as mild (1 crossing), moderate (2 crossings), or severe (>2 crossings). Tests were performed before and after IOL implantation at 1, 3, and 6 months. At mean follow-up of 6.13 months +/- 1.2 (SD), analysis of variance test judged the difference in error scores and cross tabulation represented change in number of diametrical crossings. RESULTS: The mean age was 62.3 +/- 8.5 years. All patients were men. Before IOL implantation, all patients had moderate CPRG defect on both tests. The Ishihara error score in the test and control groups did not reveal statistically significant differences (P = .505 and P = .119, respectively). With D-15, none of the patients in the test or control group showed >2 crossings. CONCLUSION: The implantation of AcrySof Natural IOL did not worsen the preexisting severity of color defect in CPRG individuals.

Colour discrimination of dental professionals and colour deficient laypersons.

OBJECTIVES: The aim of the present study was to compare results of non-dental (conventional) and dental colour discrimination tests (customized, shade guide test), to evaluate influence of profession, gender and age of colour normal dentists and laboratory technicians on colour discrimination results and to evaluate results of colour deficient laypersons. METHODS: A total of 36 colour normal dental professionals, all volunteers were divided into two groups consisting of 18 participants each: dentists (DDS) and laboratory technicians (CDT). In addition, a group 15 colour deficient males also volunteered (CDP). Colour discrimination was examined using Farnsworth-Munsell 100 Hue Test and total error scores (TES) were calculated. Participants performed a dentistry related colour discrimination test by matching 26 pairs of shade tabs. Shade guide scores (3DS) were calculated. These tests were performed under the controlled conditions of a viewing booth. Mean values and standard deviations were determined. ANOVA, Mann-Whitney test, t-test and Pearson's correlation coefficient (r) were used for result analysis. RESULTS: TES and 3DS were correlated for colour normal observers, r = 0.47 (p < 0.01). No statistically significant differences in TES and 3DS by profession, gender and age were recorded. TES of 159 (83) and 3DS of 6.7 (2.7) were recorded for colour deficient laypersons. Based on TES, 33% of colour deficient laypersons had average discrimination, whilst 67% had low discrimination. CONCLUSIONS: Within the limitation of this study, it was concluded that results of non-dental and dental colour discrimination tests were correlated, and that profession (DDS/CDT), gender and age gender did not influence colour discrimination of colour normal participants. CLINICAL SIGNIFICANCE: Although colour and appearance of dental restorations are of paramount importance for the aesthetic outcome, colour vision of dental professionals is not routinely tested. This paper validates and recommends the usage of dental shade guides for a simple, affordable and understandable testing of colour vision, either as a sole test or complementing conventional (professional) tests.

The influence of selected light intensities on color perception within the color range of natural teeth.

A study was undertaken to evaluate the influence of light intensity on the ability to discriminate color differences within the color range of natural teeth. The results show that shade selection is not significantly affected within the range of 75 to 300 fc. Neither the specialty of the dentist nor the amount of time in practice appeared to be a factor in making color discriminations. However, 7 of the 50 dentists serving as subjects were found to be color defective, and a difference was found between their color discrimination abilities and those of normal persons. This suggests that color-defective dentists should obtain assistance when matching tooth shades.

Shade selection by color vision-defective dental personnel.

This investigation studied the impairment of Hue, Value, and Chroma matching by color vision-defective dental personnel. Color-defective dental personnel were found to make significantly greater errors in Hue and Chroma selection than normal-vision dental personnel. Value, the component of shade selection considered the most important, was uneffected. Color-normal dental assistants were significantly more accurate in Hue and Chroma selection than color-defective dental personnel and could assist affected dentists in clinical situations.

For whales and seals the ocean is not blue: a visual pigment loss in marine mammals.

Most terrestrial mammals have colour vision based on two spectrally different visual pigments located in two types of retinal cone photoreceptors, i.e. they are cone dichromats with long-to-middle-wave-sensitive (commonly green) L-cones and short-wave-sensitive (commonly blue) S-cones. With visual pigment-specific antibodies, we here demonstrate an absence of S-cones in the retinae of all whales and seals studied. The sample includes seven species of toothed whales (Odontoceti) and five species of marine carnivores (eared and earless seals). These marine mammals have only L-cones (cone monochromacy) and hence are essentially colour-blind. For comparison, the study also includes the wolf, ferret and European river otter (Carnivora) as well as the mouflon and pygmy hippopotamus (Artiodactyla), close terrestrial relatives of the seals and whales, respectively. These have a normal complement of S-cones and L-cones. The S-cone loss in marine species from two distant mammalian orders strongly argues for convergent evolution and an adaptive advantage of that trait in the marine visual environment. To us this suggests that the S-cones may have been lost in all whales and seals. However, as the spectral composition of light in clear ocean waters is increasingly blue-shifted with depth, an S-cone loss would seem particularly disadvantageous. We discuss some hypotheses to explain this paradox.