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The authors compare colour differentiation of 30 phakic and 30 pseudophakic eyes, using the Farnsworth-Munsell 100-hue test. No significant difference was found between the two groups as regards differentiation of colours although theoretically it could be expected that colour differentiation will be better in eyes with a synthetic intraocular lens. The factor which has the greatest influence on colour sense is the subject's age.
Simultaneous masking using test and mask gratings composed of isochromatic luminance variations and isoluminant chromatic variations was studied. Masking of chromatic gratings by chromatic gratings shows less spatial-frequency specificity than does masking of luminance gratings by luminance gratings. Luminance gratings mask chromatic gratings of identical space-average luminance and chromaticity little and only when the spatial frequencies of the test and mask gratings are similar. Chromatic gratings, however, profoundly mask luminance gratings with a degree of spatial-frequency specificity akin to that of luminance-luminance masking. The insensitivity of the luminance-color masking results to the relative phase of the chromatic and luminance gratings indicates that the observed asymmetry is not due to local interactions.
Restricted viewing time has previously been shown to produce a tritan classification for color normal observers on the City University Colour Vision Test (CUCVT). The present investigation, which uses the Moreland anomaloscope, studies the effect of restricted viewing time on mid-match point (MMP). It shows that a color normal observer requires more green in a match under these conditions. A study of the Rayleigh equation using the Pickford Nicolson anomaloscope shows that restricted viewing time does not affect the MMP for this metameric match for color normal observers.
We encountered a new X-linked recessive cone dystrophy in which patients have a greenish-golden tapetal-like sheen of the retina; while the retinal sheen and electroretinographic abnormalities are present from childhood, patients are not symptomatic until adult years. All of the male patients tested showed evidence of cone dysfunction on color vision testing, dark adaptometry, and electroretinography. After three hours of dark adaptation, the tapetal-like sheen disappeared, with most areas changing from greenish-golden shades to orange-red hues (Mizuo-Nakamura phenomenon). One male patient had a retinal detachment from atrophic round holes in the equatorial retina.
Ocular albinism with myopia and impaired vision (R.E. 0.2; L.E. 0.6), but without nystagmus, were observed in a 10-year-old girl. The electrophysiological tests indicate, in addition, the presence of a tapetoretinal degeneration. It is assumed that the patient is carrier of two genes, a sex-linked one responsible for albinismus solum fundi and a second one of autosomal-recessive type, responsible for the tapetoretinal degenerartion.
The perception of blackness was investigated by measuring spectral efficiency and field additivity under conditions of temporal induction. For both purposes, observers foveally viewed a 0.75 deg, inducing stimulus for 5 sec followed immediately (or 200 msec later) by a broadband (5500 K) reference stimulus of the same size and spatial location. For spectral efficiency measurements, the inducing field was a monochromatic light between 400 and 700 nm (10 nm steps), while the additivity studies involved various wavelength mixtures. The psychophysical task was to increase the radiance of the inducing field until the reference stimulus just turned completely black. For two observers the spectral efficiency function of temporally-induced blackness more closely resembled their heterochromatic flicker photometry (HFP) function than their direct brightness-matching function. Their brightness functions were characterized by an inflection at about 580 nm which is generally ascribed to subtractive cone interactions, but their blackness-induction and HFP functions did not show this inflection. The brightness function of the third observer did not show an inflection at 580 nm, thereby making it difficult to differentiate between her three spectral efficiency functions. Overall, the subtle differences between the various spectral efficiency functions made it difficult to determine whether blackness induction was more similar to HFP or brightness matching. The results from the additivity tests of blackness induction, HFP and direct brightness matching removed this ambiguity from the spectral efficiency findings. Blackness induction and HFP were shown to be additive, whereas the results from brightness matching showed clear additivity failures of the cancellation type. These data support the view that the perception of blackness is mediated by neural mechanisms that additively combine the inputs of middle- and long-wave photoreceptors.
Patients complaining of reduced acuity in the absence of a clearcut diagnosis present a challenge to the eye care practitioner. It is important to differentiate retinal disease from optic nerve disease as the etiology of the decrease in vision. This differentiation can have significant ramifications and must be determined for patient welfare and management. Several procedures may be used in making the differential diagnosis of macular or retinal from optic nerve disease. Some of these procedures are easy to perform and include Amsler grid, color vision testing, pupillary reflexes, light-brightness comparison, and macular dazzle. Other procedures require a greater degree of sophistication and include fluorescein angiography, the Visual Evoked Potential (VEP) and simultaneous VEPs and ERGs (Electroretinograms). The clinician should be aware of all of these procedures and how each may be useful in this differential diagnosis.
The "Visual Retinal Profile" can be obtained in the complete office evaluation of patients with night vision disorders, unexplained poor visual acuity, or undiagnosed retinal and/or choroidal diseases. This profile allows later follow-up evaluations and comparisons of previous tests to document improvement or progression of disease. The profile consists of the usual ophthalmologic evaluation plus color vision testing Amsler grid, stereoacuity, visual fields, electroretinogram (ERG), and electrooculogram (EOG). This entire set of tests, though time consuming, can be performed in the office by an ophthalmic assistant and greatly add to the ophthalmologists ability to evaluate and diagnose subtle retinal and/or choroidal diseases. A portable ERG/EOG and light source will be described that can be used in the office, clinic, nursing home, or operating room by trained office personnel.
A generalized loss of visual sensitivity, even for foveal targets, has been reported as an early sign of glaucoma. In the present study of central vision, we used relatively simple and rapid clinical tests of color thresholds, color discrimination, and spatial contrast sensitivity to compare the vision of three age-matched groups of patients who had primary open angle glaucoma (n = 33) or ocular hypertension (n = 32) as well as normal subjects (n = 24). The largest sensitivity losses for both glaucoma and ocular hypertensive groups were disclosed by a color threshold test with blue lights designed to isolate the blue-sensitive pathways of the visual system. The loss of sensitivity for both the glaucoma group and the ocular hypertensive group is consistent with recent reports (from postmortem studies of human eyes) of extensive axon death even in the absence of glaucomatous field defects.
PURPOSE: To study colour vision and retinal nerve fibre layer (RNFL) photographs in patients with an Acrysof Natural intraocular lens (IOL). METHODS: We carried out a randomized double-blind study. An Acrysof Natural IOL (model SN60AT) was implanted in 25 eyes of 19 patients and an Acrysof IOL (model SA60AT) was implanted in 27 eyes of 18 control patients. The patients returned for colour vision tests and fundus photography 1-6 months after the surgery. RESULTS: Standard pseudoisochromatic plates, part 2, were correctly interpreted and the Farnsworth-Munsell 100-hue test (FM 100) total and individual box scores were normal in all IOL eyes. In the FM 100 hue test there were no significant differences in the results of the total error scores or the error scores of the individual boxes between the eyes with Acrysof Natural and those with Acrysof lenses. The yellow coloration of the Acrysof Natural IOL did not affect the visibility of the RNFL in photographs. CONCLUSIONS: The Acrysof Natural IOL did not affect colour vision in the tested patients, even in the blue region of the spectrum, and can be implanted in patients who need to have normal colour vision for the purposes of their occupation. The Acrysof Natural IOL does not interfere with RNFL photography and can also be used in patients with glaucoma.
A group of normal women of reproductive age were recruited to investigate colour discrimination during the various phases of the menstrual cycle. Colour vision was tested with the Farnsworth-Munsell 100-hue arrangement test, and the test was administered at 3 time points: the beginning of the cycle, ovulation, and the end of the cycle. We found that colour discrimination was better at ovulation than at the other 2 time points. It is possible that psychological as well as hormonal factors could contribute to improved colour vision performance at ovulation.
We determined the functional relationship between chromatic induction and luminance of the inducing stimulus for different spatial conditions and assessed whether the effects of luminance and spatial variables could be explained in terms of the total effective energy in the inducing field. The result showed that the relationship between chromatic induction and luminance of the inducing stimulus could be mathematically expressed by an exponential function of the luminance ratio between the test and inducing stimuli and that the coefficient of the exponent was independent of spatial variables, i.e., area and separation. This led to the conclusion that a luminance ratio between two fields, rather than a quantum energy of the inducing field, was a relevant determinant of the effect of luminance of the inducing stimulus on chromatic induction.
The DIN color chart was developed in the 1950s by Manfred Richter using of classical psychophysical scaling techniques. It is based upon the idea that colors are ordered along three subjective dimensions, i.e. hue, saturation, and brightness. Furthermore, it is assumed that the colors of the DIN color chart fulfill the principle of specific equidistancy. The main aim of this study was to investigate this claim empirically. More specifically, it was tested whether colors of the same hue and brightness are equally spaced along the dimension of subjective saturation. The data were collected in three paired comparisons experiments and were analyzed using multidimensional scaling. According to the results, the psychological properties of the DIN color system can be replicated approximately. In addition to a confirmation of the postulate of equidistancy this research contributes to the understanding of the convergence of different scaling methods.
Spectral sensitivity and color vision were investigated in 2 spider monkeys (Ateles) using a forced-choice discrimination paradigm. The increment-threshold spectral sensitivity functions of both animals were very similar to those of normal human trichromats; all had three regions of peak sensitivity located at 440-460, 520-540, and 670-620 nm. However, color vision tests (neutral point, anomaloscope, and wavelength discrimination) indicated that at least two qualitatively different types of color vision exist among spider monkeys. The female tested had essentially normal trichromatic color vision (although her anomaloscope match was shifted slightly in the deutan direction) with acute wavelength discrimination. The male, however, was clearly a protanomalous trichromat. He required much more red light in a red/green mixture to match a standard yellow than did normal trichromats. This variation in color vision is discussed in the context of an analogous variation known to exist among other South American monkeys.
Successive and simultaneous brightness comparisons between test colors and a comparison white were performed to study how accurately the brightness of colored lights was maintained in memory. The test colors were monochromatic lights chosen from 410 to 670 nm and a white light. The stimulus duration was 1 sec, and test-comparison stimulus-onset asynchronies in successive comparisons were more than 11 sec depending on the experiments. The results show that the variability of successive brightness comparisons was 1.5-2.0 times greater than that of simultaneous brightness comparison. This degree of deterioration of brightness discrimination is reasonably consistent with those of hue and saturation discrimination previously reported. Brightness shifts in the darker direction were found for most colors.
A simple method is introduced for analyzing error score distributions from the Farnsworth-Munsell 100-Hue test. The method involves fitting a sine wave directly to the error distribution, and produces estimates of three parameters that characterize the severity of the defect, the degree of bipolarity, and the orientation of the axis of bipolarity, if one is present. The method produces good estimates of the orientation of the axes for congenital defects. It is also amenable to statistical analysis.
A case of snow erythropsia is described in a patient with pseudophakia (Binkhorst four loop len). Symptoms of the condition lasted a week and allowed us to define psychophysic and electrophysiological findings. Morphoscopic night threshold was raised (0,28 b/hm 2). Resistance to glare was very low. In the study of colour vision, answers for Beyne's lantern lights were: pink orange for white; grey for blue; purple for red; red for orange; white for green. Ishihara and Farnsworth tests showed a defect of the red-green type. With the Nagel anomaloscope the matching of colours was normal (Rayleigh match). Electrophysiological study showed a low value of the standing potential of the eye and a normal electroretinogram. It seems that the colour defect in erythropsia is a glare phenomenon due to high luminance.
Eighteen patients with central serous retinopathy (CSR) underwent a battery of visual function tests when first seen and after resolution of the subretinal fluid. Eyes with CSR had minimal relative afferent pupillary defects, reduced critical flicker-fusion thresholds, prolonged visual evoked potential (VEP) latencies, increased errors on the Farnsworth-Munsell 100-hue (FM 100) test, and depressed central visual fields (Octopus). The afferent pupillary defect and critical flicker-fusion thresholds were the first to improve after resolution of the subretinal fluid. Next in rate of improvement were the visual acuity, the VEP latency, and the FM 100 test results. The threshold of the central Octopus at fixation improved the slowest and was still abnormal during long-term follow-up, indicating a prolonged depression in the threshold of central field sensitivity after resolution of the CSR. Many of these abnormalities are also seen in patients with optic nerve disease.