Color Vision in the Mountains.

This Lessons from History article uses science, aviation, medicine, and mountaineering sources to describe some of the effects of hypoxia, illumination, and other environmental conditions on the eye, the central nervous system, and light and color perception. The historical perspective is augmented by an analysis of an informal observation of the altered perception of red color on a deck of playing cards while climbing Mera Peak in the Himalaya. The appearance of a grayer red color on the cards was initially attributed to the effects of hypoxia alone.

Recommendations and requirements for the wavelengths in Rayleigh equation anomaloscopes.

DIN 6160:2019 is a technical standard that sets requirements for Rayleigh equation anomaloscopes. Table 1 of the standard contains the limits for centroid wavelengths and spectral half power bandwidths (SHBW). The centroid limits are more restrictive than dominant wavelength recommendations.

Clinical analysis of the Konan-Waggoner D15 color vision test using the Surface-Pro display.

This work expands on our previous comparison of the Konan-Waggoner D15 (KW-D15) and Farnsworth D15 (F-D15). Sixty subjects with normal color vision and 68 subjects with a red-green color vision defect participated in the study. The KW-D15 had good agreement with the F-D15 for both pass/fail and classification across all failure criteria.

Pupil light reflex in Parkinson's disease patients with and without freezing of gait symptoms.

Purpose: Freezing of gait (FOG) is considered as a motor disorder that affects some Parkinson's disease (PD) patients; however, sensory systems may also be involved in FOG. The pupil light reflex (PLR) is a reliable measure of the autonomic nervous system. Different dilation and constriction pupil parameters may be used to investigate the integrity of the autonomic nervous system in PD patients with and without FOG symptoms.

Evaluation of the Third edition of the City University Colour Vision Test.

Introduction: The 3rd edition of the City University Colour Vision Test (CUT) was originally based on the Farnsworth-Munsell D-15 test (D15). The first part of the test is for detecting a defect, and the second part is used to diagnose the type and severity of the defect. This study evaluates the CUT 3rd edition relative to the Ishihara and the D15 colour vision tests.

Visual processing and BDNF levels in first-episode schizophrenia.

Previous studies have shown that patients diagnosed with schizophrenia (SCZ) have deficits in early visual processing, namely contrast processing. The brain-derived neurotropic factor (BDNF) is an important measure to investigate neuroplasticity in some visual functions like visual perception. In this study, we investigated the relationship between visual processing and BDNF levels in first-episode SCZ patients.

A Survey on Daily Activity Inclination and Health Complaints among Urban Youth in Malaysia.

Environmental influence is one of the attributing factors for health status. Chronic interaction with electronic display technology and lack of outdoor activities might lead to health issues. Given the concerns about the digital impact on lifestyle and health challenges, we aimed to investigate the daily activity inclination and health complaints among the Malaysian youth.

Effects of Nicotine Gum Administration on Vision (ENIGMA-Vis): Study Protocol of a Double-Blind, Randomized, and Controlled Clinical Trial.

Studies reported that tobacco addiction was related to visual impairments, but one unresolved issue is whether the impairments are related to the many compounds existing in the cigarettes or to the effects of nicotine. On the other hand, nicotine gum can be used as replacement therapy or as a neuroprotective agent for some diseases. The main purpose of this controlled trial is to investigate the effects of nicotine gum on vision.

Visual processing speed in freezing and non-freezing Parkinson's disease patients.

Introduction: Parkinson's disease patients are usually characterized by body motor dysfunction due to dopaminergic reduction in the central nervous system. Freezing of gait is a motor disorder that affects certain Parkinson's disease patients. However, it is hypothesized that non-motor functions mediated by the cholinergic system are also involved in developing freezing of gait.

The CN Lantern Test and Different Viewing Distances.

Significance: This research shows that some color-vision-defective patients could identify railway signal lights correctly if they are working in the yard where sighting distances for signal lights are shorter.

Purpose: When interpreting railway signal lights, sighting distance can vary depending on the employee's location and job requirements. Individuals with a color-vision-defect may pass railroad employment color vision testing for positions with shorter sighting distances, despite failing to qualify for positions with longer sighting distances.

Predicting the CN Lantern Test for Railways with Clinical Color-vision Tests.

Significance: This research will help clinicians in advising their color-vision-defective patients regarding their career options.

Purpose: In Canadian railways, individuals with a color-vision-defect (CVD) may qualify for positions at shorter sighting distance from signal lights. The railway companies' medical units use the CN Lantern (CNLan) test, and there is little information available as to whether clinical color-vision tests (CCVTs) can predict the CNLan results.

Lighting for color vision examination in the era of LEDs: the FM100Hue Test.

Lighting conditions nominated for color vision testing are many and varied. The recommendation of CIE color rendering index (CIE CRI) ≥90 and correlated color temperature of close to 6500 K is widely made for color vision testing generally. With the demise of incandescent and fluorescent lighting and their replacement by light-emitting diodes (LEDs), this is an opportune time to revisit the recommendation.

Predicting the Farnsworth-Munsell D15 and Holmes-Wright-A lantern outcomes with computer-based color vision tests.

This study determined the AC1 agreement values between computer-based color vision tests and the Farnworth-Munsell D-15 (F-D15) and the Holmes-Wright Type A lantern (HWA). The computer-based tests were the United States Air Force Cone Contrast Test (OCCT), Cambridge Color Test, Innova Rabin Cone Contrast, Konan-Waggoner D15 (KWC-D15), and Color Assessment and Diagnosis (CAD). Sixty-eight color-vision-defective persons participated.

Limitations and Precautions in the Use of the Farnsworth-Munsell Dichotomous D-15 Test.

Significance: Clinicians who administer the Farnsworth-Munsell D-15 test need to pay attention to the quality and quantity of lighting and the time that they allow for completion of the test, and all repeat attempts need to be included in reports on compliance with color vision standards.

Purpose: The validity of the Farnsworth-Munsell D-15 has been questioned because practice may allow significantly color vision-deficient subjects to pass. In this article, we review the influence of practice and other factors that may affect the performance.

Stereopsis and ocular alignment in Parkinson's disease patients with and without freezing of gait symptoms.

Background: Parkinson's disease patients are classically described by having motor disorder symptoms. Freezing of gait is one of these motor symptoms that presents in some of these patients. Even though freezing of gait is classically considered as motor dysfunction, it is now widely accepted that deficits in other sensory systems, for example visual system, may lead or contribute to freezing of gait.

Military Research ColorDx and Printed Color Vision Tests.

Purpose: To determine the equivalence of the ColorDx Military Research version (mColorDx) test and three printed pseudoisochromatic tests (HRR, Ishihara, and PIPIC) for color vision testing.

Methods: Participating in the study were 75 color-normals and 47 subjects with red-green color vision defects. Color vision was classified by an anomaloscope.

Repeatability of Associated Phoria Tests.

Purpose: H.J. Haase developed a set of tests for measuring associated phoria and stereopsis using a variety of different targets for each.

Protan response times to red lights in a mildly hypoxic environment.

Purpose: This study was conducted to determine whether protans have slower reaction times to red lights than individuals with normal color vision and to identify whether protan reaction times increase differentially in a mildly hypoxic environment.

Methods: Simple reaction times (SRT) to a red light-emitting diode (LED) display were measured using the Psychomotor Vigilance Task (PVT) at ground (1293 ft/394 m), simulated 12,400-ft (3780-m) altitude, and 20 min after returning to ground. Subjects were 13 individuals with normal color vision (NCV), 12 with a deutan color vision defect, and 4 with a protan color vision defect.

Trichromatic and dichromatic relative sensitivity to green light in a mild hypoxic environment.

Introduction: Several studies have reported that individuals with normal color vision have a relative decrease in sensitivity to green light in hypoxic environments approximating altitudes above 4000 m. Because there is little available information describing the effects of mild hypoxic environments (less than 4000 m) in subjects with deficient color-vision, we examined the effect of mild hypoxia on the relative sensitivity to green light for color-normal and color-deficient subjects.

Methods: Relative sensitivity to the green light was measured using the Medmont C-100 at ground and 3780 m in an altitude chamber.

Forward light scatter and visual acuity through scratched protective eyewear.

Background: Scratches and other surface abrasions on protective eyewear can shorten their life cycle by scattering light from the image, which will compromise visual performance. Although scratch and abrasion resistance testing is well developed, there is little information available regarding visual acuity through lenses scratched in an actual work environment.

Methods: We collected protective eyewear from mine and smelting operations that had been returned because vision through the lenses was unacceptable due to scratches and abrasions.

Simulated night vision goggle wear and colored aftereffects.

Background: Surveys of military pilots report that between 1.6% and 65% of the respondents experienced altered color vision after night vision goggle (NVG) wear. For the majority of these pilots, the aftereffect was a brownish afterimage that lasted less than 10 min.

Hypoxia, color vision deficiencies, and blood oxygen saturation.

Chromatic thresholds were measured using the Cambridge Colour Test (CCT), the Colour Assessment and Diagnosis (CAD) test, and the Cone Specific Contrast Test (CSCT) at ground and 3780 m (12,400 ft) for subjects with normal color vision and red-green color vision defects. The CAD revealed a small (~10%) increase in the red-green thresholds for the trichromatic subjects and a similar increase in the blue-yellow thresholds for the dichromats. The other two color vision tests did not reveal any significant change in chromatic thresholds.

Does dichromatic color simulation predict color identification error rates?

Purpose: Several algorithms are available to transform colored digital images into simulated dichromatic color perception. These algorithms can be very illustrative of the problems dichromats experience in discriminating colors. The purpose of this study was to determine whether one type of transformation could provide a quantitative account of error rates in identifying colors displayed on a computer monitor.

When yellow lights look red: tinted sunglasses on the railroads.

Purpose: A major Canadian railway company purchased safety eyewear sunglasses that were purported to have a neutral gray tint and that met the North American occupational and fashion sunglass requirements for signal light transmittance. After several weeks, the company began to receive reliable reports from employees that the yellow wayside signal appeared red when viewed through these sunglasses. Furthermore, the lenses themselves appeared to have a greenish brown tint rather than gray as the labeling implied.

Do color-deficient observers take longer to complete a color-related task?

Purpose: Previous research has shown that observers with congenital red-green color vision deficiencies (color-deficient) have longer reaction and response times in making color-related judgments compared with individuals with normal color vision (color-normals). The objectives of this study were to determine how much longer color-deficient observers take to complete a visual display terminal (VDT) based color naming test without imposed time constraints, whether there was any correlation between error rate and time to complete the task, to determine the effect of familiarity on the time to complete the task, and whether the completion times were correlated with the anomaloscope or Farnsworth D-15.

Methods: The VDT task requires individuals to identify colors used to code information in a railway dispatcher display.