At the Göttingen meeting of the International Colour Vision Society, I reported on a comparison of the second edition of the American Optical Hardy-Rand-Rittler Pseudoisochromatic plates (AO HRR) with the Richmond Products third edition of the same test and concluded that the chromaticities were exceptionally poorly matched and that the new edition was a “pale imitation of the real thing” (unpublished). This conclusion led to our abandoning a clinical trial. In 2002, Richmond Products has published a fourth edition and, in 2003, Waggoner has published a modified HRR with additional (Ishihara style) plates and the tetartan confusion figures removed. As a precursor to any clinical trial, the colors used in the plates have been measured and comparisons drawn between the four editions. While the two most recent editions much more closely resemble the original AO HRR and the chromaticities are much better aligned on the dichromatic confusion lines, the excitation purities (and therefore the degree of difficulty) of the plates are less well matched in the Richmond Products editions. In addition, there is a significant degree of metamerism in the third edition and Waggoner edition that makes variations in illuminant more critical to performance.

Tobacco smoke contains a range of toxins including carbon monoxide and cyanide. With specialized cells and high metabolic demands, the optic nerve and retina are vulnerable to toxic exposure. We examined the possible effects of smoking on color vision: specifically, whether smokers perceive a different pattern of suprathreshold color dissimilarities from nonsmokers. It is already known that smokers differ in threshold color discrimination, with elevated scores on the Roth 28-Hue Desaturated panel test. Groups of smokers and nonsmokers, matched for sex and age, followed a triadic procedure to compare dissimilarities among 32 pigmented stimuli (the caps of the saturated and desaturated versions of the D15 panel test). Multidimensional scaling was applied to quantify individual variations in the salience of the axes of color space. Despite the briefness, simplicity, and “low-tech” nature of the procedure, subtle but statistically significant differences did emerge: on average the smoking group were significantly less sensitive to red–green differences. This is consistent with some form of injury to the optic nerve.

The repeatability of the D-15 color-vision test is considered to be excellent. However, this conclusion is based on a subject pool which contained a large percentage of color-normals. This type of sampling could bias the repeatability results because color-normals rarely fail the test. Furthermore, color-normals usually do not perform the D-15 in the clinical setting. To establish the repeatability of the D-15 for a relevant clinical population, we examined the D-15 results from two different sessions for 116 subjects who had a congenital red–green color-vision defect. The kappa coefficient for intersession agreement indicated that approximately 84% of the subjects obtained the same pass/fail results at both sessions. The type of defect was repeatable on approximately 80% of the subjects. Although the repeatability of the D-15 for color-defective subjects was good, it was lower than the near-perfect agreement reported previously. The coefficients of repeatability for the crossings show that if a person makes less than five crossings then the test should be administered again in order to ensure that the test result is repeatable.

Color codes in VDT displays often contain sets of colors that are confusing to individuals with color-vision deficiencies. The purpose of this study is to determine whether individuals with color-vision deficiencies (color defectives) can perform as well as individuals without color-vision deficiencies (color normals) on a colored VDT display used in the railway industry and to determine whether clinical color-vision tests can predict their performance. Of the 52 color defectives, 58% failed the VDT test. The kappa coefficients of agreement for the Farnsworth D-15, Adams desaturated D-15, and Richmond 3rd Edition HRR PIC diagnostic plates were significantly greater than chance. In particular, the D-15 tests have a high probability of predicting who fails the practical test. However, all three tests had an unacceptably high false-negative rate (9.5–35%); so that a practical test is still needed.

The Food and Drug Administration (FDA) is responsible for determining whether medical device manufacturers have provided reasonable assurance, based on valid scientific evidence, that new devices are safe and effective for their intended use before they are introduced into the U.S. market. Most existing color vision devices pose so little risk that their manufacturers are not required to submit a premarket notification [510(k)] to FDA prior to market. However, even low-risk devices may not be acceptable if they are marketed on the basis of misleading or excessive claims. Although most color vision devices are diagnostic, two types that are therapeutic rather than diagnostic are colored lenses intended to improve deficient color vision and colored lenses intended to improve reading performance. Both of these devices have presented special regulatory challenges to FDA because the intended uses and effectiveness claims initially proposed by the manufacturers were not supported by valid scientific evidence. In each instance, however, FDA worked with the manufacturer to restrict labeling and promotional claims in ways that were consistent with the available device performance data and that allowed for the legal marketing of the device.

An automated, computerized color-vision test was designed to diagnose congenital red–green color-vision defects. The observer viewed a yellow appearing CRT screen. The principle was to measure increment thresholds for three different chromaticities, the background yellow, a red, and a green chromaticity. Spatial and temporal parameters were chosen to favor parvocellular pathway mediation of thresholds. Thresholds for the three test stimuli were estimated by four-alternative forced-choice (4AFC), randomly interleaved staircases. Four 1.5-deg, 4.2 cd/m2 square pedestals were arranged as a 2 × 2 matrix around the center of the display with 15-minute separations. A trial incremented all four squares by 1.0 cd/m2 for 133 ms. One randomly chosen square included an extra increment of a test chromaticity. The observer identified the different appearing square using the cursor. Administration time was ∼5 minutes. Normal trichromats showed clear Sloan notch as defined by log (ΔY/ΔR), whereas red–green color defectives generally showed little or no Sloan notch, indicating that their thresholds were mediated by their luminance system, not by the chromatic system. Data from 107 normal trichromats showed a mean Sloan notch of 0.654 (SD = 0.123). Among 16 color-vision defectives tested (2 protanopes, 1 protanomal, 6 deuteranopes, & 7 deuteranomals), the Sloan notch was between −0.062 and 0.353 for deutans and was <−0.10 for protans. A sufficient number of color-defective observers have not yet been tested to determine whether the test can reliably discriminate between protans and deutans. Nevertheless, the current data show that the test can work as a quick diagnostic procedure (functional trichromatism or dichromatism) of red–green color-vision defect.

An earlier analysis, which yielded an optimal pair of blue and green primaries (436 & 490 nm) for tritanomaloscopy, is reevaluated. That analysis minimized population variance in the mid-match points of color normals by taking into account, for a set of blue and green tritanopic metamers, the contributions of the lens and macular pigment variances and of matching range. The revision to the matching-range contribution takes into account the effect, neglected in the original analysis, of the varying angle between the blue–green primary mixture lines and the corresponding cyan test and yellow desaturant mixture lines. Use is made of new measurements of the macular pigment absorbance spectrum, a new estimate of the lens absorbance spectrum, the population variances of the lens and macular pigment, and of matching-range data for a current Moreland equation. Tritanopic metamers are derived from a revised set of cone fundamentals. The net effect of all of these revisions on the specification of optimal primaries is small (440 and 488 nm). However, larger changes are involved in the choice of test and desaturant wavelengths.

We use the photopigment template of Baylor et al. (1987) to define the set of Rayleigh matches that would be satisfied by a photopigment having a given wavelength of peak sensitivity (λmax) and a given optical density (OD). For an observer with two photopigments in the region of the Rayleigh primaries, the observer's unique match is defined by the intersection of the sets of matches that satisfy the individual pigments. The use of a template allows us to illustrate the general behavior of Rayleigh matches as the absorption spectra of the underlying spectra are altered. In a plot of the Y setting against the red–green ratio (R), both an increase in λmax and an increase in optical density lead to an anticlockwise rotation of the locus of the matches satisfied by a given pigment. Since both these factors affect the match, it is not possible to reverse the analysis and define uniquely the photopigments corresponding to a specific Rayleigh match. However, a way to constrain the set of candidate photopigments would be to determine the trajectory of the change of match as the effective optical density is altered (by, say, bleaching or field size).

Human color vision is based fundamentally on three separate cone photopigments. Hereditary color deficiency, which affects up to 10% of males, results from an absorption shift or lack of L or M cone phototoreceptors. While hereditary S cone deficiency is rare, decreased S cone sensitivity occurs early in eye disease, underscoring the importance of quantifying S cone function. Our purpose is to describe a novel approach for quantifying human color vision based on the photopigments of normal color vision. Colored letters, visible to a single cone type, are presented in graded steps of cone contrast to determine the threshold for letter recognition. This approach quantifies normal color vision, indicates type and severity of hereditary deficiency, and reveals sensitivity decrements in various diseases.