Changes In Color Vision Research Articles

Age‐corrected monocular limits of normal trichromacy

AbstractPurpose Chromatic sensitivity worsens gradually with increasing age, but the inherent variability in normal colour vision makes this difficult to detect and to separate from very early changes caused by either retinal or systemic diseases. In this study we developed new approaches to identify and screen for changes that cannot be attributed to normal aging. This approach made it possible to produce reliable, age‐corrected limits for normal colour vision.Methods Red‐green (RG) and yellow‐blue (YB) thresholds were measured monocularly in each eye (using the Colour Assessment and Diagnosis (CAD) test) in 394 subjects (age range: 16 to 90 years). Only clinically normal subjects according to medical history and eye / fundus examination were included. All subjects with congenital colour deficiency were excluded. A new filter based on right / left eye asymmetry for RG and YB thresholds was also employed to exclude subjects with significant differences in monocular thresholds. After filtering, the analysis of the effects of normal aging was based on 178 subjects (age range: 16‐79 years).Results The effects of age (in the range 20 to 80 yrs) can be accounted for well by a linear trend with just over two‐fold increase in both RG and YB mean colour thresholds. Statistical limits of variability (±2σ) were computed from the normal subject data in order to provide limits of age‐corrected RG and YB colour vision.Conclusion The age‐corrected CAD thresholds limits established in this study provide a more accurate way of detecting monocular changes in colour vision caused by either retinal diseases or systemic conditions that affect the eye.

Changes in color vision with decreasing light level: separating the effects of normal aging from disease

The purpose of this study was to obtain additional information about the health of the retina (HR) by measuring the rate of loss of chromatic sensitivity with decreasing light level. The HR(index) is introduced to separate the effects of normal aging from early stage disease. For normal subjects the HR(index is largely independent of age (r(2)~0.1), but ~11% of clinically normal, asymptomatic, older subjects exhibit values below the 2σ limit. The HR(index provides a single number that captures how light level affects chromatic sensitivity irrespective of age and can be used to screen for preclinical signs of retinal disease.

Funciones visuales en portadores del virus de inmunodeficiencia humana

Objective To determine whether there are changes in the peripapillary nerve fibre layer, in colour vision, contrast sensitivity, dark adaptation and electroretinography changes in these patients who do not have infectious retinitis. Methods We studied 52 patients without ocular pathology; the mean age was 35.88 years old. Results We observed less thickness in all quadrants, except the nasal. The colour vision was altered in 27.77% of the patients. The contrast sensitivity test showed high frequency alterations. There was no statistically significant difference in the electroretinography test or in dark adaptation. Conclusions There are changes in the peripapillary nerve fibre layer thickness; also we found changes in colour vision, contrast sensitivity and a decreasing trend of the B wave in the electroreninogram.

Visual function evaluation in human immunodeficiency virus carriers

ObjectiveTo determine whether there are changes in the peripapillary nerve fibre layer, in colour vision, contrast sensitivity, dark adaptation and electroretinography changes in these patients who do not have infectious retinitis. MethodsWe studied 52 patients without ocular pathology; the mean age was 35.88 years old. ResultsWe observed less thickness in all quadrants, except the nasal. The colour vision was altered in 27.77% of the patients. The contrast sensitivity test showed high frequency alterations. There was no statistically significant difference in the electroretinography test or in dark adaptation. ConclusionsThere are changes in the peripapillary nerve fibre layer thickness; also we found changes in colour vision, contrast sensitivity and a decreasing trend of the B wave in the electroreninogram.

A Sensory Origin for Color-Word Stroop Effects in Aging: Simulating Age-Related Changes in Color-vision Mimics Age-Related Changes in Stroop

ABSTRACT An increase in Stroop effects with age can be interpreted as reflecting age-related reductions in selective attention, cognitive slowing, or color-vision. In the present study, 88 younger adults performed a Stroop test with two color-sets, saturated and desaturated, to simulate an age-related decrease in color perception. This color manipulation with younger adults was sufficient to lead to an increase in Stroop effects that mimics age-effects. We conclude that age-related changes in color perception can contribute to the differences in Stroop effects observed in aging. Finally, we suggest that the clinical applications of Stroop take this factor into account.

Photopigment polymorphisms and color vision: Lessons from nonhuman primates

The functional impacts and genetic bases of the human photopigment polymorphisms have been intensively studied and debated. Even though they attract much attention, photopigment polymorphisms that cause significant changes in color vision are relatively infrequent in humans and effectively absent in other catarrhine primates. By contrast, photopigment polymorphisms are near universal in New World (platyrrhine) monkeys and they also appear sporadically among the more primitive strepsirrhine primates. Recent studies of these pigment polymorphisms, particular those of the platyrrhines, have significantly enhanced our understanding of a number of fundamental aspects of color vision. Among other things, these polymorphisms have (a) been exploited to detail the relationships between opsin gene structures and pigment spectral tuning, (b) been used to illustrate how X-chromosome inactivation can serve as a tool for adding perceptual capacity, and (c) provided real insights into the evolution of primate trichromacy. As well, these photopigment polymorphisms now provide an attractive resource for studying the ecology of primate color vision and a framework for testing hypotheses about the organization of primate visual systems.

Simulating Age-Related Changes in Color Vision to Assess the Ability of Older Adults to Take Medication

To determine if simulated, age-related changes in color vision can adversely affect one's ability to properly take medication as simulated by bead selection. Randomized controlled study. University site. University students 18 to 26 years of age without eye disorders that would affect color vision. Yellow-lens glasses to represent age-related color vision changes. The number of correct beads selected and rating of task difficulty. The secondary outcomes were participants' responses based on which colors and color pairs were most difficult to discern and strategies they might have used to select beads. The control group had no difficulties in selecting the appropriate beads, while the experimental group had significantly more mistakes, particularly with colors in the blue-violet spectrum. Average scores for the total number correct for the control and experimental groups were 36 (100%) and 27 (74.4%), P < 0.001, respectively, out of a possible 36 correct. Declines in color vision with age can adversely affect an individual's abilities to appropriately select medications. For patients taking several medications, declines in color vision should be considered when counseling older persons on strategies for compliance. Although more studies are still needed to further generalize these findings to the geriatric population, this study has shown color vision can adversely affect medication compliance.

Cataracts in Airline Pilots: Prevalence and Aeromedical Considerations in Japan

Despite modern aviation being increasingly less dependent on human factors, the pilot is still part of the aircraft systems and vision is critical for flight safety. The incidence of cataract increases with age, but as most epidemiological studies focus on senior age groups, there is no data relevant to working age groups. The aim of our study was to elucidate the prevalence of lens opacity in Japanese airline pilots. A retrospective cohort study was conducted at the Japan Aeromedical Research Center. Medical records for all ophthalmological assessments performed in the 12-mo period prior to March 2008 were reviewed. Data collected included whether there was documented lens opacity or a history of previous cataract surgery. Over 12 mo, 3780 pilots underwent slit-lamp examination with an ophthalmologist as part of their scheduled medical and 105 pilots were identified with cataract. Out of these, 59/105 were bilateral, 29/105 were congenital types (of which 19 were bilateral), and 12/105 pilots gave a history of previous cataract surgery. In all 105 pilots, the visual acuity was sufficient to continue the privileges of their licenses. This study offers insight into the clinical iceberg of early cataracts in persons of working age. Mild and early lens opacities can cause significant glare and haze, and changes in color vision, which might compromise pilot performance even in the absence of decreased visual acuity. Cataracts in otherwise fit pilots have important aeromedical significance which requires further consideration.

Impairment of color spatial vision in chronic alcoholism measured by psychophysical methods.

We used psychophysical tests to evaluate spatial vision in 15 subjects with a clinical history of chronic alcoholism by measuring luminance contrast sensitivity and color discrimination. The subjects were initially subjected to clinical inquiry and ophthalmological exam. Subjects then performed psychophysical tests to measure spatial contrast thresholds using sine wave gratings of different spatial frequencies and contrasts and chromatic discrimination thresholds using the Mollon-Reffin test. For the analysis, subjects were divided into three groups according to age and compared with age-matched controls. Ten subjects had some degree of color vision loss, which was quite severe in seven cases. All subjects had normal luminance contrast sensitivity. The results suggest that color vision changes related to chronic alcoholism can occur in the absence of impairment of spatial luminance contrast sensitivity and thus is an important aspect to be considered in the clinical evaluation of this condition.

Color vision in children and the Lanthony New Color Test

Much is known about color vision in infants, adolescents, and adults, but very few studies report the changes, which occur in color perception of children in their early schooling years. There is also a shortage of suitable color vision tests for children. This study investigated the changes in color vision of school students between 5-12 years old using the Lanthony New Color Test (NCT). Subjects of all ages were able to complete a shortened form of this test adequately. The Vingrys and King-Smith (1988) method of panel test analysis and Adams and Rodic (1982) color confusion score were adapted to analyze their performance of the test. This study confirmed that there are changes in color perception occurring in this age group. Color perception abilities increased as a function of age and there was also an improvement in the performance on the NCT with age. This can be attributed to both cognitive development and changes occurring to the color vision system.

A prospective study of change in visual function in patients treated with pegylated interferon alpha for hepatitis C in the UK

Background:Hepatitis C virus and interferon treatment have been associated with retinopathy. Baseline and ongoing assessment by ophthalmologists have therefore been advocated in previous studies. Our experience suggests that the incidence...

Nilutamide and Chromatopsia: Suggestion for a Possible Mechanism

Results: Delayed adaptability to darkness, characterised as a delay in recovering visual function after bright illumination (sun, bright light), is the most frequent adverse effect in patients with prostatic carcinoma receiving nilutamide alone or in combination with orchiectomy or luteinizing hormonereleasing hormone (LHRH) agonists. Detailed opthamological examination revealed an increase in the photostress recovery time to an average of 9 minutes, while the upper limit of normal is 1 minute and 20 seconds. The photostress recovery time is the time required to read the Snellen test letters on the line above that of best corrected visual acuity. Chromatopsia has been associated with the use of various drugs. In the human eye, the cones that are mainly situated in the macula, are maximally receptive to short, medium, and long wavelengths and response to blue, greenish and red light. Colour perception mainly occurs in the macula. The delayed photostress recovery time, is also indicative of an impaired function of the macula. Although the mechanism associated with the change in colour perception associated with nilutamide is not known, it is very likely that a differential adaptation to light of the various types of cones of the macula may play a role in the pathogenesis of this phenomenon. This is supported by the fact that both patients reported a change in colour vision together with this delayed adaptability to darkness.

Cone weights for the two cone-opponent systems in peripheral vision and asymmetries of cone contrast sensitivity

In understanding the basis of the changes in human color vision across eccentricity, one key piece of information remains unknown, whether the relative cone weights of the two cone opponent mechanisms vary. Here we measure detection threshold contours within three planes in a 3-dimensional cone contrast space to reveal the L, M and S-cone weights to the two cone opponent mechanisms, L/M and S/(L + M). We find these remain constant across eccentricity suggesting the underlying structures of the cone opponent mechanisms are invariant. The contrast sensitivities of two poles of the S-cone opponent mechanism also remain symmetrical, whereas small asymmetries develop in L/M opponency from about 15°.

Evolutionary variation in the expression of phenotypically plastic color vision in Caribbean mantis shrimps, genus Neogonodactylus

Many animals have color vision systems that are well suited to their local environments. Changes in color vision can occur over long periods (evolutionary time), or over relatively short periods such as during development. A select few animals, including stomatopod crustaceans, are able to adjust their systems of color vision directly in response to varying environmental stimuli. Recently, it has been shown that juveniles of some stomatopod species that inhabit a range of depths can spectrally tune their color vision to local light conditions through spectral changes in filters contained in specialized photoreceptors. The present study quantifies the potential for spectral tuning in adults of three species of Caribbean Neogonodactylus stomatopods that differ in their depth ranges to assess how ecology and evolutionary history influence the expression of phenotypically plastic color vision in adult stomatopods. After 12 weeks in either a full-spectrum “white” or a narrow-spectrum “blue” light treatment, each of the three species evidenced distinctive tuning abilities with respect to the light environment that could be related to its natural depth range. A molecular phylogeny generated using mitochondrial cytochrome oxidase C subunit 1 (CO-1) was used to determine whether tuning abilities were phylogenetically or ecologically constrained. Although the sister taxa Neogonodactylus wennerae and N. bredini both exhibited spectral tuning, their ecology (i.e. preferred depth range) strongly influenced the expression of the phenotypically plastic color vision trait. Our results indicate that adult stomatopods have evolved the ability to undergo habitat-specific spectral tuning, allowing rapid facultative physiological modification to suit ecological constraints.

Successful treatment of oleander intoxication (cardiac glycosides) with digoxin-specific Fab antibody fragments in a 7-year-old child

A 7-year-old girl presented six hours after ingestion of a yellow oleander seed (Thevetia peruviana) with severe emesis, change in colour vision and complete heart block. Initial treatment with phenytoin and isoprenalin infusion led to intermittent supraventricular and ventricular tachycardia. The patient was then treated with two intravenous doses of 190 mg of digoxin-specific Fab antibody fragments (Digibind). Subsequently the patient's rhythm reverted to sinus rhythm and the symptoms resolved within 2 hours. administration of digoxin-specific Fab antibody fragments in an otherwise healthy child after oleander intoxication is safe and without adverse reactions.

Effect of sildenafil on ocular hemodynamics in 3 months regular use

The aim of this study was to evaluate the effect of sildenafil on ocular hemodynamics in a group of men with erectile dysfunction in 3 months regular use. A total of 15 patients with erectile dysfunction were included in this prospective study. All patients received 50 mg doses of sildenafil (Viagra, Pfizer) two times per week regularly for 3 months. The following examinations were performed on both eyes before and after sildenafil treatment: best-corrected visual acuity (BCVA), intraocular pressure (IOP), color vision, anterior segment, and fundus examination. Using color Doppler imaging, we measured hemodynamic variables in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary artery (SPCA). No significant changes in BCVA, color vision and IOP were found after sildenafil treatment. The anterior segment and fundus examinations showed no abnormalities. All Doppler parameters of OA, CRA, and SPCA remained nonsignificant for both eyes after sildenafil treatment. Oral sildenafil in 3 months regular use seems to have no effect on ocular hemodynamics.

Silent substitution S‐cone electroretinogram in subjects with diabetes mellitus

A defect in the blue sensitive mechanism has been reported in certain ocular and systemic diseases. For example, tritanopic colour vision defects and changes to the S-cone electroretinogram (ERG) have been demonstrated in glaucoma and diabetes mellitus. Electrophysiological methods of eliciting the S-cone ERG, however, often result in considerable L- and M-cone intrusion. We report the findings of a study employing the silent substitution S-cone ERG technique, which is thought to represent an almost pure S-cone signal, and the L'Anthony desaturated D15 colour vision test in subjects with Type 1 or 2 diabetes mellitus with no or minimal background retinopathy. The results of this study show a significantly increased S-cone ERG b-wave implicit time and significantly worse colour vision in those with background retinopathy compared with those with no diabetic retinopathy. This suggests that S-cone pathway dysfunction may be responsible for the deterioration in colour vision found in diabetes mellitus.

Compound May Be Effective In Reducing Alzheimer’s Plaques

Back to table of contents Previous article Next article Clinical & Research NewsFull AccessCompound May Be Effective In Reducing Alzheimer’s PlaquesMark MoranMark MoranSearch for more papers by this authorPublished Online:6 Feb 2004https://doi.org/10.1176/pn.39.3.0023bClioquinol appeared to decrease levels of plasma beta amyloid, the protein whose toxic accumulation in the brain is believed to be centrally linked to Alzheimer’s disease, and led to improvement on the Alzheimer’s Disease Assessment Scale (ADAS) score in those with the most severe disease.The compound, which had been withdrawn for oral use in 1970 because of its association with subacute myelo-optic neuropathy, was well tolerated. Authors of the small study, appearing in the December 2003 Archives of Neurology, said that the results argue for reconsideration of the drug’s use and for larger clinical trials.Clioquinol is a compound that inhibits zinc and copper ions from binding to beta amyloid, thereby promoting the dissolution of that protein and diminishing its toxic properties.In the study, 36 patients were randomized to receive treatment with clioquinol or placebo. The oral dosage of clioquinol was 125 mg twice daily from weeks 0 to 12, 250 mg twice daily from weeks 13 to 24, and 375 mg twice daily from weeks 25 to 36.Patients who had a baseline ADAS score of 25 or more and were in the treatment arm showed a trend toward significant improvement on the score at weeks 4 and 24, compared with patients who were in the placebo arm and also had baseline scores of 25 or more. Plasma beta-amyloid levels declined in the clioquinol group and increased in the placebo group.“The findings support a proof of concept in humans that a drug targeting metal beta-amyloid interactions can have a significant effect on beta-amyloid metabolism and, through this, a beneficial modification on the progression of Alzheimer’s,” wrote Craig B. Ritchie, M.B.Ch.B., and colleagues at the Mental Health Research Institute of Victoria at the University of Melbourne, Australia.“The significant benefit seen in the more severely affected treatment group at four weeks [on the ADAS scores]. . .may represent the short-term effect of clioquinol neutralizing the neurotoxicity of the soluble pool of beta amyloid.”The authors acknowledged that safety is of concern in a study involving the chronic administration of a drug with a history of adverse events. Clioquinol-associated optic neuropathy was suspected in one patient with a history of eye disease. But they said a direct causal link to clioquinol remains uncertain, given that “disturbances of color vision and other ophthalmologic changes occur during the natural history of Alzheimer’s disease.”They added that 27 patients have agreed to participate in an open-label extension study of clioquinol, and that 10 of those have been receiving the drug at a dosage of 500 mg/d to 750 mg/d for more than 18 months. No clioquinol-attributable adverse events have developed in any of these patients, they reported.In an accompanying editorial, Roger N. Rosenberg, M.D., editor of the Archives of Neurology, said zinc-copper chelation offers promise as a new therapeutic strategy. “Clearly, it is an innovative therapeutic approach to Alzheimer’s disease and merits a closer and more comprehensive assessment in larger clinical trials.”An abstract of the study, “Metal-Protein Attenuation With Iodochlorhydroxyquin (Clioquinol) Targeting A Amyloid Deposition and Toxicity in Alzheimer Disease: A Pilot Phase 2 Clinical Trial,” is posted online at http://archneur.ama-assn.org/cgi/content/abstract/60/12/1685. ▪ Arch Neurol 2003 60 1685 ISSUES NewArchived

Does Occupational Exposure to Organic Solvents Affect Colour Discrimination?

This review assesses the evidence regarding the effects of occupational exposure to organic solvents on colour discrimination and investigates exposure-response relationships and reversibility. This review also considers the current state of knowledge of the possible mechanisms underlying changes in colour vision, and the human health significance of any reported changes. Among the commonly used organic solvents, styrene has been investigated the most thoroughly. Studies of styrene-exposed workers in Germany, Italy and Japan provide a sufficiently consistent body of evidence to support a robust conclusion that styrene does cause an impairment of colour discrimination relative to age-matched controls. Generally, the impairment of colour discrimination observed in styrene-exposed workers tends to be of the tritan (blue-yellow) type, although some cases of red-green impairment have also been found. The limited information available on exposure-response relationships indicates that the effects on colour discrimination would not be expected at 8-hour time weighted average (8 h TWA) exposures <20 ppm, although a precise threshold cannot be determined. The data on reversibility are limited and inconclusive. The results from the most rigorous study in which this aspect was investigated point to a reversibility of effects after a 4-week exposure-free period, whereas results from a study with limitations suggest a persistence of effect. The effects of toluene, tetrachloroethylene or mixed solvent exposure have also been investigated, although the information available is generally less reliable than for styrene. For toluene, it can be confidently concluded that this solvent does not have an acute effect on colour discrimination, even when exposures are relatively high (50-150 ppm 8 h TWA, and 290-360 ppm 30 minutes TWA). However, studies are inconclusive on whether long-term or repeated exposure to toluene can cause a persistent impairment of colour discrimination. There are few studies that have specifically investigated the effects of tetrachloroethylene on colour discrimination. Among these studies, none has examined the potential for any acute effects of this solvent vapour. A large-scale study in Japanese workers showed no effects of long-term exposure to tetrachloroethylene concentrations in the region of 12-13 ppm. However, the test methodology used was relatively insensitive to changes in colour discrimination, hence the results do not provide reassurance for an absence of subtle effects. A study in Italian dry-cleaners suggested a slight impairment of colour discrimination relative to controls, associated with relatively low exposures to tetrachloroethylene (mean 8 h TWA exposure approximately 6 ppm). The studies concerning the effects of mixed solvent exposure on colour discrimination are based on workers exposed to solvents in paints and lacquers, workers from the printing and petrochemical industries, people working in or living near to microelectronics factories and children exposed to solvents prenatally. However, these studies are subject to design limitations or methodological irregularities, such that no conclusions regarding the effects of mixed solvent exposure on colour discrimination can be drawn. Overall, the only credible evidence for an effect of solvents on colour discrimination derives from the studies on styrene. Because of limitations in the data for other solvents it is not possible to determine whether the evidence for styrene reflects a generic property of solvents. The mechanisms of styrene-induced effects on colour discrimination have not been properly investigated and can only be the subject of speculation. One conclusion that can be drawn is that pathological changes to the ocular system, such as changes to the lens, are unlikely to be involved. This is because there is an absence of convincing evidence for such changes from medical examinations conducted in epidemiological studies of solvent-exposed workers. Also, it seems unlikely that effects on colour discrimination are a nonspecific consequence of more generalised CNS depression, given that styrene-induced effects on colour discrimination appear to occur below the threshold for narcotic effects. The effects of styrene on colour discrimination are subtle and involve an impairment of the ability to discriminate accurately between closely related shades of the same colour rather than 'colour blindness'. There is no valid basis for using colour discrimination as a marker for other forms of solvent-induced neurotoxicity.

Efficacy and tolerability of tadalafil, a novel phosphodiesterase 5 inhibitor, in treatment of erectile dysfunction

Advances in molecular biology and protein chemistry, along with increasing understanding of the mechanisms of penile erection, have spurred development of pharmacologic approaches to the treatment of erectile dysfunction (ED). The next generation of oral agents includes tadalafil, a potent, highly selective phosphodiesterase 5 inhibitor. In vitro studies have shown that tadalafil enhances relaxation of trabecular smooth muscle, and clinical trials have supported its efficacy and tolerability in a broad population of men with ED. The effect of tadalafil in enhancing the erectile response to sexual stimulation is relatively rapid in onset and lasts for ≥24 hours. The ability of patients with ED treated with tadalafil to achieve improved erectile function is demonstrated by significantly increased subjective measures of penetration ability, successful intercourse, and sexual satisfaction. Partners have expressed similar or higher levels of satisfaction with the results of treatment. Men with ED of psychogenic, organic, or mixed etiology and in a range from mild to severe have experienced significant improvment with tadalafil treatment. Response to treatment in men with diabetes has been robust and not affected by disease severity. Tadalafil has been well tolerated. Adverse events have generally been mild or moderate and have abated with continued treatment. Headache and dyspepsia have been most frequently reported. Changes in color vision have been rare (<0.1%) with tadalafil across all clinical trials. Tadalafil appears to be a safe and effective treatment for men with ED.