Color Confusion Index Research Articles

Visual Characteristics of Adults with Long-Standing History of Dietary Exposure to Mercury in Grassy Narrows First Nation, Canada.

Since the 1960s, Grassy Narrows First Nation (Ontario, Canada) has been exposed to methyl mercury (Hg) through fish consumption, resulting from industrial pollution of their territorial waters. This cross-sectional study describes the visual characteristics of adults with documented Hg exposure between 1970 and 1997. Oculo-visual examinations of 80 community members included visual acuity, automated visual fields, optical coherence tomography [OCT], color vision and contrast sensitivity. Median age was 57 years (IQR 51-63) and 55% of participants were women. Median visual acuity was 0.1 logMAR (Snellen 6/6.4; IQR 0-0.2). A total of 26% of participants presented a Visual Field Index inferior to 62%, and qualitative losses assessment showed concentric constriction (18%), end-stage concentric loss (18%), and complex defects (24%). On OCT, retinal nerve fiber layer scans showed 74% of participants within normal/green range. For color testing with the Hardy, Rand, and Rittler test, 40% presented at least one type of color defect, and with the Lanthony D-15 test, median color confusion index was 1.59 (IQR 1.33-1.96). Contrast sensitivity showed moderate loss for 83% of participants. These findings demonstrate important loss of visual field, color vision, and contrast sensitivity in older adults in a context of long-term exposure to Hg in Grassy Narrows First Nation.

Low-level occupational exposure to BTEX and dyschromatopsia: a systematic review and meta-analysis

Objectives. The present study aimed to assess whether occupational exposure to low concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) is associated with color vision impairment. Methods. We queried PubMed, Scopus, Embase, Web of Science and ProQuest as the main databases, as well as gray literature such as Google Scholar. A random-effects model was used to assess relative risk. A funnel plot was created to assess publication bias. Meta-regression analysis was applied to identify variables that explain the between-study variation in the reported risk estimate. Results. An overall standardized mean difference of 0.529 (95% confidence interval [0.269, 0.788]; p < 0.0001) was obtained in the random-effects model, which corresponded to a medium-size effect. Duration and the levels of exposure to benzene, toluene and xylene were the significant predictors of the magnitude of the combined risk estimate. Chronic exposure to low levels of BTEX was associated with dyschromatopsia determined by the color confusion index. Conclusions. The impairments can occur even at exposures lower than the occupational exposure limits of BTEX. However, there are several flaws in the determination of workers’ exposure, which did not allow to establish how low a level of these chemicals can cause color vision impairment.

Elaborate Evaluation of Farnsworth Dichotomous D-15 Panel Test Can Help Differentiate between Best Vitelliform Macular Dystrophy and Autosomal Recessive Bestrophinopathy

Introduction: The colour vision in bestrophinopathies has not been assessed in detail so far. The aim of this study was to explore the extent to which distinct types of bestrophinopathies differ in regard to colour vision deficiencies using Farnsworth Dichotomous D-15 and Lanthony Desaturated D-15 panel tests. Methods: Both D-15 tests were performed in 52 eyes of 26 patients with Best vitelliform macular dystrophy (BVMD) and 10 eyes of 5 patients with autosomal recessive bestrophinopathy (ARB). Two methods were used for a quantitative assessment of the colour vision deficiencies: moment of inertia method and Bowman method. The following parameters were calculated: confusion angle, confusion index (C-index), selectivity index (S-index), total error score (TES), and colour confusion index (CCI). Results: The median value of confusion angle for all stages of BVMD fell into a narrow range around 62, indicating normal results. The median confusion angle value was 57 in ARB patients within a very wide range down to −82, indicating non-specific deficits. These differences were statistically significant. Significantly abnormal C-index and CCI values were found only in ARB patients, being 2.0 and 1.49, respectively. The majority of parameters of D-15 tests were independent of the visual acuity in both bestrophinopathies. Conclusions: Elaborate evaluation of the D-15 panel tests might help establish a differential diagnosis between different bestrophinopathies, as the pattern of the colour vision loss is different between BVMD and ARB. The quantitative parameters of colour vision tests in bestrophinopathies are independent of the visual acuity.

Dyschromatopsia in multiple sclerosis reflects diffuse chronic neurodegeneration beyond anatomical landmarks

AbstractPurpose: To formulate and validate a dyschromatopsia linear regression model in patients with multiple sclerosis (MS).Methods: 64 MS patients (50 to formulate the model and 14 for its validation) underwent neurological (Expanded Disability Status Scale, EDSS), colour vision (Farnsworth D15 test), and peripapillary retinal nerve fibre layer (pRNFL) and retinal evaluation with spectral‐domain optical coherence tomography (SD‐OCT). Neuroradiological examination permitted to obtain brain parenchymal fraction (BPF) and cervical spinal cord volume (SC). Ophthalmic parameters were calculated as the average of both non‐optic neuritis (ON) eyes, and in case the patient had previous ON, the value of the fellow non‐ON eye was taken. The influence of sex, age, disease duration and history of disease‐modifying treatment (first‐ or second‐line DMT) was tested as covariables that could influence colour perception.Results: Colour confusion index (log CCI) correlated with pRNFL (r = −0.322, p = 0.009), ganglion cell layer (GCL, r = −0.321, p = 0.01), BPF (r = −0.287, p = 0.021), SC volume (r = −0.33, p = 0.008), patients' age (r = 0.417, p = 0.001), disease duration (r = 0.371, p = 0.003) and EDSS (r = 0.44, p = 0.001). The following CCI equation was obtained: log (CCI) = 0.316–0.224 BPF –0.187 SC volume (mm3) +0.226 age (years) +0.012 disease duration (years) −0.372 GCL (μm).Conclusions: CCI correlates with MS clinical and paraclinical established biomarkers suggesting chronic diffuse neurodegeneration in MS operates at brain, SC and retina linking all three compartments. Colour vision outcome can be calculated through the aforementioned variables for clinical and research purposes.

Color Vision in the Gas Station Workers of Isfahan City: A Quantitative Analysis With the Farnsworth D15 Color Test

Background and Objectives: The color vision evaluation of gas station workers in Isfahan City. Methods: This cross-sectional comparative study was performed on workers at gas stations in Isfahan; all the workers were men. The participants were divided into two 40-people groups of exposure and non-exposure (the members of the fuel sales department). The participants had better vision than 8/10 and no underlying problems or eye disease. Besides, examination, including color vision was performed for all subjects. Color vision was assessed using the D15 test under high to medium light conditions. Also, the color vision test was performed monocularly. Then, the obtained data were analyzed using SPSS V. 22. Results: The two study groups significantly differed in terms of color vision impairment index (P &lt;0.001). Also, more color vision defects were seen in the group exposed to gasoline. The color confusion index (as the indicator of color vision defects) were 1.485 and 1.129 in exposure and non-exposure to gasoline groups, respectively. Thus, color vision defects were significantly higher in the exposure to gasoline group, compared with the control group. Conclusion: The results of this study showed a difference in color vision index between the two groups. Therefore, long-term exposure to organic solvents, such as gasoline in fuel stations may cause color vision loss.

Dyschromatopsia in multiple sclerosis reflects diffuse chronic neurodegeneration beyond anatomical landmarks.

To formulate and validate a dyschromatopsia linear regression model in patients with multiple sclerosis (MS). 64 MS patients (50 to formulate the model and 14 for its validation) underwent neurological (Expanded Disability Status Scale, EDSS), color vision (Farnsworth D15 test), and peripapillary retinal nerve fiber layer (pRNFL) and retinal evaluation with spectral-domain optical coherence tomography (SD-OCT). Neuroradiological examination permitted to obtain brain parenchymal fraction (BPF) and cervical spinal cord volume (SC). Ophthalmic parameters were calculated as the average of both non-optic neuritis (ON) eyes, and in case the patient had previous ON, the value of the fellow non-ON eye was taken. The influence of sex, age, disease duration, and history of disease-modifying treatment (first- or second-line DMT) was tested as covariables that could influence color perception. Color confusion index (log CCI) correlated with pRNFL (r = - 0.322, p = 0.009), ganglion cell layer (GCL, r = - 0.321, p = 0.01), BPF (r = - 0.287, p = 0.021), SC volume (r = - 0.33, p = 0.008), patients' age (r = 0.417, p = 0.001), disease duration (r = 0.371, p = 0.003), and EDSS (r = 0.44, p = 0.001). The following CCI equation was obtained: log (CCI) = 0.316-0.224 BPF -0.187 SC volume (mm3) + 0.226 age (years) + 0.012 disease duration (years) -0.372 GCL (µm). CCI correlates with MS clinical and paraclinical established biomarkers suggesting chronic diffuse neurodegeneration in MS operates at brain, SC, and retina linking all three compartments. Color vision outcome can be calculated through the aforementioned variables for clinical and research purposes.

HUBUNGAN LAMA PAPARAN INHALASI ORGANICSOLVENT TERHADAP PENURUNAN PENGLIHATAN WARNA DAN SENSITIVITAS KONTRAS

&lt;p&gt;&lt;em&gt;Chronic inhalation of organic solvents causes retinal toxicity such as decreased color vision and contrast sensitivity because organic solvents cause damage to photoreceptor function, changes in cortical or retinal neurotransmitter systems such as glutamate, dopamine and acetylcholine and changes in function in parvo, magno and coniocellular cells.&lt;/em&gt;&lt;em&gt; &lt;/em&gt;&lt;strong&gt;&lt;em&gt;Method&lt;/em&gt;&lt;/strong&gt;&lt;em&gt;: The sample of this study consisted of 45 gas station operators who were divided into 3 groups, namely those who worked 1 year&lt;/em&gt;&lt;em&gt;-&lt;/em&gt;&lt;em&gt;5 years, 5 years&lt;/em&gt;&lt;em&gt;-&lt;/em&gt;&lt;em&gt;10 years and &lt;/em&gt;&lt;em&gt;&amp;gt;&lt;/em&gt;&lt;em&gt;10 years. All subjects underwent &lt;/em&gt;&lt;em&gt;q&lt;/em&gt;&lt;em&gt;uantitative color vision examination by calculating the value of the color confusion index (CCI) using Fansworth D15. Contrast sensitivity examination is by determining the log contrast sensitivity value using the Pelli-Robson test.&lt;/em&gt;&lt;em&gt; &lt;/em&gt;&lt;strong&gt;&lt;em&gt;Results&lt;/em&gt;&lt;/strong&gt;&lt;em&gt;: CCI values&amp;gt; 1.00 and log contrast sensitivity values &amp;lt;1.65 were found in officers who worked for &lt;/em&gt;&lt;em&gt;&amp;gt;&lt;/em&gt;&lt;em&gt;10 years by 12 subjects (80%). Statistically there is a significant relationship between the duration of work with the decrease in color vision and contrast sensitivity (P Value 0,000).&lt;/em&gt;&lt;em&gt; &lt;/em&gt;&lt;strong&gt;&lt;em&gt;Conclusion&lt;/em&gt;&lt;/strong&gt;&lt;em&gt;: There is a significant relationship between the duration of exposure to organic solvents with a decrease in color vision and contrast sensitivity in operator officers who work &lt;/em&gt;&lt;em&gt;&amp;gt;&lt;/em&gt;&lt;em&gt;10 years.&lt;/em&gt;&lt;/p&gt;

The neuro-ophthalmological effects related to long-term occupational exposure to organic solvents in painters.

Organic solvents are widely used in many industries, and usually, exposure occurs with mixtures of solvents. Organic solvent mixtures are known for their ability to affect tissues of high lipid content including the myelin sheath in the nervous system. The purpose of this work was to study the evidence that long-term (more than 10 years) exposure to organic solvent mixtures among painters can induce neuro-ophthalmological effects on the function of retinal ganglion cells and the optic tract. Twenty workers with long-term occupational exposure to mixed organic solvents were compared to 40 control subjects. The controls were matched for age, gender, and demographic characteristics but were not occupationally exposed to any known organic solvents, using the following comparators: visual evoked potential (VEP), electroretinogram (ERG), color vision (CV), and contrast sensitivity (CS) testing. Environmental monitoring was done in the work environment with consideration to the American Conference of Governmental Industrial Hygienists Threshold Limit Values (ACGIH-TLVs). The exposed group had significantly longer latency and higher amplitude of VEP waves especially P100, higher Color Confusion Index (CCI), especially affecting the blue-yellow spectrum, and lower Log CS. There was no significant difference between exposed and nonexposed groups in full-field flash ERG response; however, in the pattern ERG, the exposed group had significantly longer latency of P50, which reflects changes in the retinal ganglion cell. Long-term occupational exposure to mixed organic solvents appeared to affect the optic tract functions in the form of increasing latency of VEP response, affecting the quality of CV and decreasing CS. It also affects the retinal ganglion cell layer with increased latency of P50 of the pattern ERG response.

Visual dysfunction and retinal changes in patients with multiple sclerosis

PurposeTo evaluate structural changes in the retina and their correlation with visual dysfunction in patients with multiple sclerosis.MethodsPatients with multiple sclerosis (n = 84) and healthy controls (n = 84) underwent structural evaluation of the retinal nerve fiber layer, and macular and ganglion cell layer thicknesses using Spectral domain optical coherence tomography (SD‐OCT). All subjects underwent high and low contrast visual acuity, color vision (using the Farnsworth and L′Anthony desaturated D15 color tests), and contrast sensitivity vision using the Pelli Robson chart and CSV 1000E test.ResultsMacular, retinal nerve fiber layer, and ganglion cell layer thinning was observed in multiple sclerosis patients compared to healthy controls (p &lt; 0.05). High and low contrast visual acuity and contrast sensitivity vision at four different spatial frequencies were significantly reduced, compared with healthy subjects (p &lt; 0.05). Macular, retinal nerve fiber layer and ganglion cell layer measurements correlated with high and low contrast visual acuity, and contrast sensitivity vision. Contrast sensitivity vision was the functional parameter that most strongly correlated with the structural measurements in multiple sclerosis and was associated with ganglion cell layer measurements. The L′Anthony color vision score (age‐corrected color confusion index) was associated with macular measurements.ConclusionsPatients with multiple sclerosis had visual dysfunction that correlated with structural changes evaluated by SD‐OCT. Macular and ganglion cell layer measurements may be good indicators of visual impairment in multiple sclerosis patients.

Relationship between Visual Dysfunction and Retinal Changes in Patients with Multiple Sclerosis.

AimTo evaluate structural changes in the retina and their correlation with visual dysfunction in patients with multiple sclerosis.MethodsPatients with multiple sclerosis (n = 84) and healthy controls (n = 84) underwent structural evaluation of the retinal nerve fiber layer, and macular and ganglion cell layer thicknesses using Spectral domain optical coherence tomography (SD-OCT). All subjects underwent high and low contrast visual acuity, color vision (using the Farnsworth and L´Anthony desaturated D15 color tests), and contrast sensitivity vision using the Pelli Robson chart and CSV 1000E test.ResultsMacular, retinal nerve fiber layer, and ganglion cell layer thinning was observed in multiple sclerosis patients compared to healthy controls (p<0.05). High- and low-contrast visual acuity and contrast sensitivity vision at four different spatial frequencies were significantly reduced in comparison with healthy subjects (p<0.05). Macular, retinal nerve fiber layer and ganglion cell layer measurements correlated with high and low contrast visual acuity, and contrast sensitivity vision. Contrast sensitivity vision was the functional parameter that most strongly correlated with the structural measurements in multiple sclerosis and was associated with ganglion cell layer measurements. The L´Anthony color vision score (age-corrected color confusion index) was associated with macular measurements.ConclusionsPatients with multiple sclerosis had visual dysfunction that correlated with structural changes evaluated by SD-OCT. Macular and ganglion cell layer measurements may be good indicators of visual impairment in multiple sclerosis patients.

Visual functions of workers exposed to organic solvents in petrochemical industries.

Aim:The purpose of this study was to evaluate the visual functions of workers exposed to organic solvents in petrochemical industries.Materials and Methods:Thirty workers from the petroleum refinery and 30 age-matched controls (mean age) were recruited. Visual functions and occupational exposure levels were assessed among both the groups. Visual acuity, contrast sensitivity, color vision, and visual fields were evaluated at the workplace. The biological samples, namely blood and urine, were collected at the workplace and transported to the laboratory for analysis. The urinary excretion of hippuric and methylhippuric acid as well as creatinine was measured by high performance liquid chromatography.Results:The mean age of the workers and controls were 39.7 ± 7.6 years and 38.6 ± 8.1, years respectively. The mean years of experience of the workers were 15.6 ± 6.8 years. Visual acuity was >0.01 LogMAR among both the control and case groups. The contrast sensitivity was reduced at 12cpd among workers. Comparison between groups was done using independent sample t-test. The mean difference in color confusion index was 0.11 ± 0.05 (P = 0.037*). The mean difference in visual fields was −0.31 ± 0.36 dB (P = 0.933). The mean difference in urinary hippuric acid level (urinary metabolite of toluene) between the groups was 0.19 ± 0.96 g/g creatinine (P = 0.049FNx01). The mean difference in the excretion of methylhippuric acid (urinary metabolite of xylene) was 0.06 ± 0.04g/g creatinine (P = 0.154). We also found that exposure was a significant risk factor for color vision defect with an odds ratio of 4.43 (95% CI: 1.36–14.4); P = 0.013.Conclusion:The study results showed that contrast sensitivity and color vision were affected among workers in petrochemical industry.

Ability of Bottle Cap Color to Facilitate Accurate Patient–Physician Communication Regarding Medication Identity in Patients with Glaucoma

To determine the accuracy of patient-physician communication regarding topical ophthalmic medication use based on bottle cap color, particularly among individuals who may have acquired color vision deficiency from glaucoma. Cross-sectional, clinical study. Patients aged ≥18 years with primary open-angle, primary angle-closure, pseudoexfoliation, or pigment dispersion glaucoma, bilateral visual acuity of ≥20/400, and no concurrent conditions that may affect color vision. A total of 100 patients provided color descriptions of 11 distinct medication bottle caps. Color descriptors were then presented to 3 physicians. Physicians matched each color descriptor to the medication they thought the descriptor was describing. Frequency of patient-physician agreement, occurring when all 3 physicians accurately matched the color descriptor to the correct medication. Multivariate regression models evaluated whether patient-physician agreement decreased with degree of better-eye visual field (VF) damage, color descriptor heterogeneity, or color vision deficiency, as determined by the Hardy-Rand-Rittler (HRR) score and Lanthony D15 color confusion index (D15 CCI). Subjects had a mean age of 69 (±11) years, with VF mean deviation of-4.7 (±6.0) and-10.9 (±8.4) decibels (dB) in the better- and worse-seeing eyes, respectively. Patients produced 102 unique color descriptors to describe the colors of the 11 bottle caps. Among individual patients, the mean number of medications demonstrating agreement was 6.1/11 (55.5%). Agreement was less than 15% for 4 medications (prednisolone acetate [generic], betaxolol HCl [Betoptic; Alcon Laboratories Inc., Fort Worth, TX], brinzolamide/brimonidine [Simbrinza; Alcon Laboratories Inc.], and latanoprost [Xalatan; Pfizer, Inc., New York, NY]). Lower HRR scores and higher D15 CCI (both indicating worse color vision) were associated with greater VF damage (P < 0.001). Extent of color vision deficiency and color descriptor heterogeneity significantly predicted agreement in multivariate models (odds of agreement= 0.90 per 1 point decrement in HRR score, P < 0.001; odds of agreement= 0.30 for medications exhibiting high heterogeneity [≥11 descriptors], P= 0.007). Physician understanding of patient medication use based solely on bottle cap color is frequently incorrect, particularly in patients with glaucoma who may have color vision deficiency. Errors based oncommunication using bottle cap color alone may be common and could lead to confusion and harm.

0233 Long-term styrene exposure impairs colour vision in fibreglass reinforced plastics laminators

ObjectivesAlthough styrene has been reported to cause colour vision impairment, the results were still inconclusive. Whether the impairment was related to short-term or long-term exposure was not known. The study...

Ophthalmic findings in acute mercury poisoning in adults

The aim of this study is to report ophthalmic findings of acute mercury poisoning in 48 adults referred to emergency department. Full ophthalmologic examination including the best corrected visual acuity, external eye examination, reaction to light, a slit-lamp examination, funduscopy, intraocular pressure measurements, and visual field (VF) and color vision (CV) tests were performed at the presentation and repeated after 6 months. The parametric values of VF test, the mean deviation (MD), and pattern standard deviation (PSD) were recorded in order to compare patients and the 30 healthy controls. The mean parameter of color confusion index in patients was found to be statistically different than controls (p < 0.01). The MD and PSD in patients were different from controls statistically significant (p < 0.01 and p < 0.01, respectively). There was no correlation between the ocular findings and the urine and blood mercury levels. Methyl mercury, held in the school laboratory for experimental purpose, may be a source of poisoning. In this case series, we showed that acute exposure to mercury had hazardous effect on the visual system, especially CV and VF. We propose that emphasizing the public education on the potential hazards of mercury is crucial for preventive community health.

Ophthalmic Findings of Acute Mercury Poisoning in Primary School Students

Purpose: To report ophthalmic findings in acute mercury poisoning in the primary school students. Methods: Seventy two children exposed to mercury vapor and 42 healthy controls were enrolled in the study. Full ophthalmologic examination including best corrected visual acuity, external eye examination, a slit-lamp examination, funduscopy, intraocular pressure measurements, Visual Field (VF), Visual Evoked Potential (VEP) and Color Vision (CV) tests were performed at the presentation and after six months. The parametric values of VF, Mean Deviation (MD) and Pattern Standard Deviation (PSD) were compared between groups. Results: The visual acuity less than two lines in ETDRS chart in 7(9.7%) patients, color vision impairment in 6(8.3%) patients were determined with ophthalmic examination. There were a significant difference in the color confusion index of patients, (p<0.05). The mean parametric VF values of MD and PSD were found statistically, significant difference (p<0.001, p<0,001 respectively), The latency values of VEP were 7% of 20 patients over 100 ms. There were no correlation between ophthalmic findings and mercury levels in urine and blood. Conclusion: While visual acuity minimally affected, advanced visual functions were significantly impaired in a way independent of mercury level. The goal of this paper is to draw attention to the importance of public education on potentially hazardous effects of mercury in terms of preventive community health. In particular, both primary school teachers and students should be trained concerning poisonous gases such as mercury.

Mercury exposure and color vision loss of some Koreans in a fishery area

This study was conducted to evaluate the relationship between exposure to mercury and color vision loss in populations located within fishery areas in South Korea. From a total of 511 subjects, 401 were assessed for acquired color vision loss. Subjects determined to have congenital loss or subjects with visual acuity less than 0.6 were excluded from the study. Mercury concentrations were analyzed in blood, urine, and hair samples. The Ishihara test was used to assess congenital color vision loss, and the Lanthony test was used for acquired color vision loss. Acquired color vision loss was present in 56 (14%) of the subjects and 345 (86%) subjects were normal. The geometric means of mercury concentration were 3.78 μg/L in blood, 0.64 μg/g creatinine in urine, and 1.16 μg/g in hair. Although mercury was identified in relatively low concentrations, mercury concentrations in subjects with acquired color vision loss were higher than that of normal subjects. The frequency of color vision loss in subjects with higher mercury concentrations was increased compared to subjects with lower mercury concentrations. The color confusion index increased with increasing mercury levels. This study suggests that exposure to low levels of mercury affects color vision loss as an early marker of neurotoxic damage in humans.

Association Between Retinal Nerve Fiber Layer Thickness and Abnormalities of Vision in People With Human Immunodeficiency Virus Infection

To investigate relationships between contrast sensitivity (CS), color vision, and retinal nerve fiber layer (RNFL) among people with human immunodeficiency virus (HIV) infection; to evaluate the effect of time since diagnosis of HIV infection on RNFL thickness. Noninterventional cross-sectional study. We evaluated 102 eyes of 57 HIV-infected individuals without ocular opportunistic infections. Peripapillary RNFL thickness was determined with spectral-domain optical coherence tomography in 4 quadrants. CS was measured with the Pelli-Robson technique (expressed as logCS); color vision was measured with the Lanthony desaturated 15-hue technique (expressed as color confusion index [C-index], with higher scores indicating worse color vision). Correlations between values were assessed using Spearman correlation coefficients. Median RNFL thickness (average of 4 quadrants) was 102.9 μm (range, 75.0-134.7 μm). Median logCS was 1.90 (range, 1.25-1.95). Median C-index was 1.58 (range, 0.96-4.07). Temporal RNFL thickness was correlated with logCS (r=0.295, P=.003) and C-index (r=-0.338, P=.0005). Time since diagnosis of HIV infection was shorter for those with thick average RNFL than for those with thin average RNFL (P=.18). Both worse CS and worse color vision are correlated with thinning of the temporal RNFL, with possible threshold effects. Increased prevalences of abnormal CS and abnormal color vision in this population are therefore likely attributable to neuroretinal compromise. This pattern of structural and functional losses may reflect preferential damage to small-caliber axons in the maculopapillary bundle, possibly associated with mitochondrial dysfunction, providing a potential disease mechanism for HIV-associated "neuroretinal disorder."

Impairment of color vision in aircraft maintenance workers

The purpose of the study was to examine possible persisting effects to color vision in a group from the Royal Australian Air Force who had exposure to formulations containing neurotoxins during F-111 fuel tank maintenance, relative to two contemporaneous comparison groups. Color vision was tested in 512 exposed personnel, 458 technical-trade comparisons, and 330 non-technical comparisons using the Ishihara test plates and the Lanthony D-15 Desaturated Color disk arrangement test. Participants were excluded if they failed the Ishihara test as this indicates congenital color blindness. From the Lanthony results, the type of color deficient vision (CDV) was diagnosed, and additionally, the Bowman's color confusion index (CCI) was calculated. Regression models were used to examine whether there was an association between color vision deficiencies and F-111 fuel tank maintenance, adjusting for possible confounders. The CCI ranged from 1 to 2.8 (median 1.2, quartiles 1.1, 1.4) in the 2,600 eyes tested. Forty five percent of all participants had blue-yellow CDV in at least one eye. Deficiencies of this nature are caused by environmental exposures. Logistic regression demonstrated statistically significant differences in CCI category in the exposed group versus technical group (odds ratio 1.7: 95% CI 1.3-2.0) and a blue-yellow confusion in the exposed group versus technical group (odds ratio 1.4: 95% CI 1.1-1.7). No differences were observed between the exposed group and the non-technical group. The results indicate reduced color discrimination among the exposed subjects compared to one of two control groups. The findings may be due to previous exposure to solvents among the air force personnel.

Occupational exposure to different levels of mixed organic solvents and colour vision impairment

Mixed organic solvents have a broad range of applications in industry. Occupational exposure to organic solvents has been shown to be associated with colour vision impairment. The study was designed to determine the impact of chronic occupational exposure to organic solvent mixtures on colour vision of car industry painters. 408 workers of assembly location and 2 different paint locations of a car manufacturing company were included in the study. The workers were studied in three groups. The first group consisted of those working in the assembly location with no exposure to organic solvents. The second and third groups included those working in the new and old paint locations, exposed to organic solvents at lower and higher levels than the permissible level, respectively. The Lanthony D-15 desaturated (LD-15) test was used for screening acquired colour vision impairment. The frequency of acquired colour vision impairment was 44.28% for workers of the old paint location, 29.31% for workers of the new paint location, and 3.90% for workers of the assembly location, indicating a significant difference ( p < 0.001). The results of logistic regression indicated there was a significant relationship between colour confusion index (CCI) and exposure to organic solvents ( p < 0.001) for the old and new paint locations. We suggest that chronic occupational exposure to organic solvents at higher and even lower levels than the permitted levels may lead to acquired colour vision impairment. It is recommended that LD-15 test would be implicated in the early diagnosis of nervous system disorders in workers exposed chronically to organic solvents.

Occupational styrene exposure, colour vision and contrast sensitivity: a cohort study with repeated measurements

Associations between occupational styrene exposures and impairment of visual functions were investigated with a view to answering three questions: (1) are the published findings for colour vision deficiencies and impaired contrast sensitivity to reproduce in a new study approach, (2) if such effects exist, are they related to current or chronic exposures and (3) if effects exist, are there reductions in the effects during an exposure-free period? Workers from a boat building plant were examined in groups of current low [n = 97, mean mandelic acid (MA) + phenylglyoxylic acid (PGA) = 51 mg/g creatinine], medium (n = 115, mean = 229 mg/g creatinine) and high (n = 30, mean = 977 mg/g creatinine) level exposure to styrene. Job tenure was about 6 years. In addition, subgroups chronically exposed to low-short (n = 34, lifetime weighted mean 200 mg/g creatinine for 6 years) and high-long (n = 17, mean = 660 mg/g creatinine, 15 years) styrene levels were analysed. The examinations were carried out during normal working days and during the company holidays. Colour vision was investigated with the Lanthony desaturated panel D-15d using the colour confusion index (CCI) as a relevant variable. Contrast sensitivity was investigated with the Vistech charts VCTS 6500 using frequency-related results as well as total scores as variables. Co-variance analyses with repeated measurements and multiple linear regressions were used for statistical analysis. There was no evidence of significant associations between exposure parameters and CCI. This is true for the analyses with all participants as well as for those with the subgroups with high-long versus low-short exposure. Thus, no exposure related changes in the relevant variables were found during the exposure-free period. The analyses for contrast sensitivity show similar results. The largest portions of the variances in both tests were explained by age. German as mother tongue covered a considerable portion of the CCI variances. Education, long-term alcohol use and job tenure explain only partly significant portions of the test variances exhibited. Both acute styrene exposure levels of 40 ppm (range of standard deviation up to 54 ppm) and long term exposures to 27 ppm (range of standard deviation up to 44 ppm with higher exposure levels in the past) for a period of about 15 years were not identified as causing elevated risks for the investigated parameters of colour vision and contrast sensitivity. This statement contradicts the published results for styrene-related colour vision deficiencies but it seems to be compatible with published results for contrast sensitivity due to styrene exposure.