Color-blindness simulation for red-green and blue-yellow ambiguity

Color blindness has important effects on people’s daily activities, since most activities require a discernment between colors. It is very important for engineers and designers to understand how colorblind people perceive colors. Therefore, many methods have been proposed to simulate color perception of people affected by Dichromacy and anomalous Trichromacy. However, the simulation results rarely have been evaluated with the reports of concerned individuals. In first study, we tried to simulate the color perception of people with different types (red and green) and different degrees of color blindness. Different degrees of red-green deficiency is simulated on the 24-plates brand of the Ishihara color vision test kit. Then simulated plates were tested on people with normal color vision. The results show that the simulation performance is better in the case of high degrees of red-green deficiency. There is also a clear difference between the assessment of female and male volunteers. In another study, the perception of the color of people with blue-yellow blindness is also considered. The proposed blue-yellow blind simulation is compared with the result of another research project. The results show that the color perception of individuals with different degrees of blue-yellow blindness can be reconstructed with a reasonable accuracy.

Frequency of Color Blindness in Driving License Candidates Presenting in Allied Hospital, Faisalabad

Background: Color vision is an integral part of visual functions. Defective color vision may leadto difficulties in daily activities and even choosing and continuing in a certain profession. Colorvision deficiency or blindness may be congenital or acquired due to retinal or optic nerve disorders Aim: To investigate the frequency of color blindness or weakness in driving license candidates presenting for medical exam, for the year 2019. Methodology: The study design was descriptive cross sectional and the sampling technique wasnon probability convenient sampling. The place of study was eye outdoor of Allied Hospital,Faisalabad. The sample size was 13,637 based on inclusion criteria. The subjects ranged in agefrom 18 years onwards to a maximum presentation of 76 years with mean age as 30.728 ±10.131.Both genders were included in the study. Visual acuity was tested on Snellen’s Chart andrefraction, if needed, was performed to obtain best corrected acuity. Results: The results of the study showed that most of the subjects had 6/6 vision as 96.6% in righteye and 96.5% in left eye, 6/9 as 2.8% and 2.9% and 6/12 as 0.3% and 0.4% respectively for rightand left eye. The frequency of normal color vision was 94%, 4.9% for red green deficiency and 1.1% for color blindness. Conclusion: A frequency of 4.9% and 1.1% for color deficiency and color blindness respectively, in drivers, indicates that color vision must be tested to avoid any possible accidents related todeficient color perception. Keywords: Driving license, colorblindness

Persistent Dark Cones in Oligocone Trichromacy Revealed by Multimodal Adaptive Optics Ophthalmoscopy

Dark cone photoreceptors, defined as those with diminished or absent reflectivity when observed with adaptive optics (AO) ophthalmoscopy, are increasingly reported in retinal disorders. However, their structural and functional impact remain unclear. Here, we report a 3-year longitudinal study on a patient with oligocone trichromacy (OT) who presented with persistent, widespread dark cones within and near the macula. Diminished electroretinogram (ERG) cone but normal ERG rod responses together with normal color vision confirmed the OT diagnosis. In addition, the patient had normal to near normal visual acuity and retinal sensitivity. Occasional dark gaps in the photoreceptor layer were observed on optical coherence tomography, in agreement with reflectance AO scanning light ophthalmoscopy, which revealed that over 50% of the cones in the fovea were dark, increasing to 74% at 10° eccentricity. In addition, the cone density was 78% lower than normal histologic value at the fovea, and 20–40% lower at eccentricities of 5–15°. Interestingly, color vision testing was near normal at locations where cones were predominantly dark. These findings illustrate how a retina with predominant dark cones that persist over at least 3 years can support near normal central retinal function. Furthermore, this study adds to the growing evidence that cones can continue to survive under non-ideal conditions.

AN EXPERIMENT USING THE GRAPHIC VARIABLE COLOR AND THE SEE COLOR CODE ON ISARITHMIC MAPS ACCESSIBLE TO BLIND AND NORMALLY SIGHTED PEOPLE

The See Color is a color coding system based on Braille writing to communicate colors to people with visual impairments. This study assessed the perception of the theme Temperature by blind people, by using the See Color code on two isarithmic tactile maps and the perception of subjects with normal color vision. An average temperature map of Australia had 10 classes, but these intervals were regrouped into four classes on Corel Draw software. The new map was duplicated in the digital project in A4 size, both included the See Color code in two color schemes obtained from the Color Brewer website. Subsequently, they were laser-printed on swell paper to produce the tactile relief. The chromatic perception was observed, as well as the thermal sensations that the colors could represent for blind participants (06), normally sighted participants in basic education (23), and normally sighted participants in higher education (20). In this research, the See Color code showed the potential to provide spatial knowledge as a graphic language through colors in color maps for adventitiously blind and for normally sighted participants based on their perception of colors and tactile color codes.

Prevalence of Color Vision Deficiency among Dental Practitioners and its Effect on Shade Matching Ability

Objective: Shade selection is a crucial step in achieving aesthetically-pleasing restorations, and it is affected by the dentist’s ability to match the shade of the patient’s teeth. Color Deficiency Disease (CVD) has been thought to be a potential factor affecting color perception. The study aims to find the prevalence of CVD between dentists and dental students and to evaluate its effect on shade matching ability. Methods: A sample of 319 dentists and dental students in the College of Dentistry at Ajman University, Ajman, UAE was examined with the Ishihara test to find the prevalence of CVD. Then participants with CVD were tested for shade matching ability, and were compared to participants with normal color vision with the same gender and qualification level. They were asked to match 10 random composite samples with different shades to a custom shade guide made from the same composite material. A score was calculated, representing the number of correct answers they achieved. Results: The results showed that 8 out of 143 males (5.6%) had CVD, and 0 out of 176 females had CVD. There was no significant difference in the score of shade matching test between participants with CVD and participants with normal color vision (p=0.075). Conclusion: Males showed a higher prevalence of color vision deficiency than females. CVD had no significant effect on shade matching ability.

Color image evaluation of congenital red-green color deficient and normal color vision observers

How and to what extent the increase of Cab * affects on various subjective evaluations for congenital red-green color deficiency (CVD) and normal color vision (NCV) observers was investigated using scenery, food, and graph images. Results of "Pale vs Deep" evaluation indicate similar tendency for all color vision types in all test images, indicating that CVDs recognize the saturation change of images similar to NCVs using some kind of strategy. Individual differences of the CVDs in the results of other adjective pairs such as "Unnatural vs Natural" are generally larger than those of NCVs. Some color combinations in the graph images are indiscriminable for either protan or deutan, and thus are not recommended to be used.

Spectral Filter Selection for Increasing Chromatic Diversity in CVD Subjects

This paper analyzes, through computational simulations, which spectral filters increase the number of discernible colors (NODC) of subjects with normal color vision, as well as red–green anomalous trichromats and dichromats. The filters are selected from a set of filters in which we have modeled spectral transmittances. With the selected filters we have carried out simulations performed using the spectral reflectances captured either by a hyperspectral camera or by a spectrometer. We have also studied the effects of these filters on color coordinates. Finally, we have simulated the results of two widely used color blindness tests: Ishihara and Farnsworth–Munsell 100 Hue (FM100). In these analyses the selected filters are compared with the commercial filters from EnChroma and VINO companies. The results show that the increase in NODC with the selected filters is not relevant. The simulation results show that none of these chosen filters help color vision deficiency (CVD) subjects to pass the set of color blindness tests studied. These results obtained using standard colorimetry support the hypothesis that the use of color filters does not cause CVDs to have a perception similar to that of a normal observer.

Temporary Tritanopia: Effects of cataract surgery on color

This pilot study made a wide variety of visual measurements before, during, and after bilateral cataract surgery. This article describes the changes in color discrimination and color appearance resulting from cataract implants. It used the F-M 100 Hue Test, color matching of real scenes, and color-balance titration measurements. The pre-surgery data indicated that the previously normal color observers had severe tritanopic anomalies. Lens replacement restored normal color vision.