6. Oral contraceptives.
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Color Vision Defects↗
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Visual results of a long-term trial of a low-arginine diet in gyrate atrophy of choroid and retina.
Visual function has been serially assessed in two gyrate atrophy patients who have had long-term reduction of plasma ornithine concentrations by a low-arginine diet. One patient demonstrated subjective and objective improvement after 15 months of treatment. In addition to improvements in dark adaptation thresholds, enlargement of visual fields, and a more normal electroretinogram, there was marked improvement in cone function as measured by color vision. There has been no change noted in the second patient. These results suggest that reduction of plasma ornithine may be beneficial in gyrate atrophy patients and that the high ornithine concentrations characteristic of this disorder play some role in the pathophysiology.
Adult↗
Eye movement abnormalities in rod monochromacy.
Eye movements were studied quantitatively using electro-oculography in seven patients with rod monochromacy. Attention was given to eye movement abnormalities that could help to differentiate rod monochromacy from other forms of congenital nystagmus. Horizontal nystagmus in center gaze had pendular and jerk waveforms with much lower amplitude than that in patients with other forms of congenital nystagmus and visual acuity of 20/200-20/400. Slow build-up of slow component velocity over many seconds and directional asymmetry of optokinetic nystagmus (OKN) were observed during monocular optokinetic stimulation. The directional asymmetry of OKN was characterized by a higher OKN gain (eye velocity/OKN drum velocity) during rotation of the OKN drum in the temporal-to-nasal direction in the visual field, than that during drum rotation in the nasal-to temporal direction. Similar directional asymmetry and slow build-up are found in afoveate animals, such as the rabbit, during monocular optokinetic stimulation, but are not found in normal human subjects or in patients with other forms of congenital nystagmus.
Adolescent↗
Pattern dystrophy of the retinal pigment epithelium.
The pattern dystrophies are a group of hereditary macular dystrophies characterized by lesions of the retinal pigment epithelium (RPE) arranged in various patterns of dots, lines, and branched figures. This report of two pedigrees expands the clinical spectrum. The onset is usually in the second and third decade, there is great variation in fundus appearance, vision may be severely affected, the EOG is not always abnormal, and the fundus lesions change with time. The lesions resemble those of Best's vitelliform degeneration and fundus flavimaculatus, and, possibly, also represent abnormal lipofuscin accumulation within degenerating retinal pigment epithelial cells.
Adolescent↗
The relationship between hue discrimination and contrast sensitivity deficits in patients with diabetes mellitus.
In an attempt to elucidate more fully the pathophysiologic basis of early visual dysfunction in patients with diabetes mellitus, color vision (hue discrimination) and spatial resolution (contrast sensitivity) were tested in diabetic patients with little or no retinopathy (n = 57) and age-matched visual normals (n = 35). Some evidence of visual dysfunction was observed in 37.8% of the diabetics with no retinopathy and 60.0% of the diabetics with background retinopathy. Although significant hue discrimination and contrast sensitivity deficits were observed in both groups of diabetic patients, contrast sensitivity was abnormal more frequently than hue discrimination. However, only 5.4% of the diabetics with no retinopathy and 10.0% of the diabetics with background retinopathy exhibited both abnormal hue discrimination and abnormal contrast sensitivity. Contrary to previous reports, blue-yellow (B-Y) and red-green (R-G) hue discrimination deficits were observed with approximately equal frequency. In the diabetic group, contrast sensitivity was reduced at all spatial frequencies tested, but for individual diabetic patients, significant deficits were only evident for the mid-range spatial frequencies. Among diabetic patients, the hue discrimination deficits, but not the contrast sensitivity abnormalities, were correlated with the patients' hemoglobin A1 level. A negative correlation between contrast sensitivity at 6.0 cpd and the duration of diabetes also was observed.
Adult↗
Idiopathic photoreceptor dysfunction causes unexplained visual acuity loss in later adulthood.
Progressive visual loss, caused by initially unrecognized retinal photoreceptor dysfunction predominantly affecting cones, developed in six patients in late adulthood. Because of minimal ophthalmoscopic retinal abnormalities, the patients initially had been suspected of having optic neuropathy or psychogenic visual loss. The correct diagnosis was ultimately established by finding electroretinographic abnormalities and color discrimination losses out of proportion to visual acuity loss. In no case was a causative agent or a family history of photoreceptor disease identified. In many other respects, however, features of the patients' illness resemble those described previously under the headings of cone dysfunction syndrome, cone dystrophy, cone degeneration, and cone-rod dystrophy.
Aged↗
Lasers, light hazards, and the clinician.
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Color Vision Defects↗
Acute idiopathic blind spot enlargement. A spectrum of disease.
The authors present a report on their experience with 10 patients with acute idiopathic blind spot enlargement. All had enlarged steep-margined blind spots without accompanying changes in optic disc appearance, significantly diminished visual acuity or color vision. Fluorescein angiography was obtained in eight patients. Five patients had retinal appearance that was either normal or could not be attributed to a known disease entity. Three patients had the multiple evanescent white dot syndrome, one had acute macular neuroretinopathy, and at least one had presumed ocular histoplasmosis. It has been proposed that acute idiopathic blind spot enlargement is a subset of multiple evanescent white dot syndrome. The authors' findings suggest that multiple evanescent white dot syndrome and other retinal diseases, some not yet identified, are subsets of acute idiopathic blind spot enlargement.
Acute Disease↗
Cutaneous melanoma-associated retinopathy.
PURPOSE: To define further the syndrome of cutaneous melanoma-associated retinopathy, of which only five affected patients have been reported previously. METHODS: Three men with melanoma-associated retinopathy were examined and studied electrophysiologically. Two were studied in detail psychophysically. RESULTS: Visual symptoms consisted of flickering black and white spots, shimmering patches of colors, and night blindness. The onset was acute and nonprogressive. Reduced amplitudes were observed in the flash electroretinographic b-wave and the pattern electroretinogram. Color vision, contrast sensitivity, and light- and dark-adapted perimetric sensitivities were abnormal. In one patient, the rate of dark adaptation was normal with elevated final cone and rod thresholds. CONCLUSIONS: Melanoma-associated retinopathy is a paraneoplastic syndrome distinct from cancer-associated retinopathy with a different visual prognosis. It may preferentially affect men.
Aged↗
Macular dystrophy associated with mutations at codon 172 in the human retinal degeneration slow gene.
BACKGROUND: Recently, mutations in the retinal degeneration slow (rds) gene which codes for peripherin-rds have been implicated as a cause of autosomal dominant retinitis pigmentosa. Because this gene is expressed in both rods and cones, mutations in the rds gene might be expected to cause degeneration affecting either the scotopic or photopic systems. Mutations at codon 172 of the rds gene have been identified in three families with autosomal dominantly inherited, progressive macular dystrophy. METHODS: Affected individuals underwent ophthalmic examination, scotopic perimetry, dark adaptometry, measurement of color-contrast sensitivity, and electroretinography to characterize the photoreceptor dysfunction. RESULTS: In all but one affected member, symptoms of progressive central visual loss developed in the third or fourth decade of life accompanied by central scotoma and well-demarcated atrophy of the retinal pigment epithelium and choriocapillaris of the macula. In general, cone and rod thresholds were elevated, and color-contrast sensitivity was absent in the central visual field. Peripherally, the scotopic sensitivities were normal, as was the recovery from bleach. Cone electroretinograms were diminished in amplitude, and delayed in all affected adults except one. Rod electroretinograms were normal or near normal in amplitude, and had normal implicit times. Affected asymptomatic children had macular changes, abnormal color-contrast sensitivity, and reduced pattern and cone electroretinograms. CONCLUSION: These results indicate that mutations in the rds gene can be expressed as a macular dystrophy, with evidence of primary cone dysfunction and preservation of peripheral rod function.
Adolescent↗
Laser pointers and color blindness.
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Audiovisual Aids↗
Laser pointers and color blindness.
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Audiovisual Aids↗
Color vision and occupational chemical exposures: I. An overview of tests and effects.
The paper presents a summary of the literature published until December 2000 on effects from some industrial chemical exposures on color perception, as well as short descriptions of the tests applied. Several different tests have been used to study acquired alterations of color vision. These changes are frequently found in the blue-yellow axis. Many of the tests were originally designed to detect congenital alterations in the red-green axis, and thus have relatively low sensitivity when studying chemically induced deficits in color perception. At present, the Lanthony D15-desaturated panel seems most suitable for application in industrial settings, since it is clearly the most sensitive and easily administered test. Color vision seems to be a physiological function very sensitive to several chemicals. The potency of industrial chemicals to induce color vision deficiencies has often been investigated during the last two decades. The chemicals most frequently studied are different solvents and mercury. Pronounced effects on color perception have been reported following chronic exposure to organic solvents such as styrene, carbon disulphide, perchloroethylene, n-hexane and solvent mixtures, and to organic as well as inorganic mercury. The effect of occupational toluene exposure seems not as well established, since only slight effects and several negative studies have been reported. For some of these compounds the effect on color vision has been further established through the finding of clear dose-effect relationships. In a few cases, even acute exposure situations, e.g. exposure to toluene for a few hours or acute alcohol intake, seem to affect color perception. Follow-up studies are needed to investigate the possible reversibility of effects in relation to discontinued or reduced exposures.
Color Perception Tests↗
Assessment of visual functions following prenatal exposure to organic solvents.
Prenatal exposure to organic solvents has been previously associated with increased risk of color vision deficits and reduced visual acuity in young children. These findings prompted us to evaluate visual functioning in solvent-exposed infants using more sensitive non-invasive visual evoked potential (VEP) techniques. VEP techniques are described in the context of an ongoing prospective longitudinal cohort study of infants exposed to organic solvents in utero. VEPs are recorded via three active electrodes fitted over the occipital cortex while infants view changing visual stimuli. The sweep VEP is used to assess contrast detection and visual acuity by presenting sinusoidal gratings that "sweep" across a range of contrasts and spatial frequencies. Transient VEPs are used to assess responses to equiluminant chromatic- and luminance-modulated sinusoidal gratings presented in pattern onset-offset format. A single case study is presented showing abnormal chromatic responses and reduced contrast sensitivity in a 2.5-year-old boy following prenatal exposure to perchloroethylene (PCE). These VEP techniques therefore appear promising for the clinical assessment of visual toxicity in pediatric populations.
Child, Preschool↗
Visual dysfunction in workers exposed to a mixture of organic solvents.
The aim of this study was to investigate the relationship between the workers occupationally exposed to a mixture of organic solvents and their visual functions. Here the visual functions included color vision (CV), visual contrast sensitivity (CS) and visual evoked potentials (VEP). Test subjects were 182 workers at 53 furniture factories in the same industrial area of Japan. As control, a group consisted of 96 workers without exposure to any organic solvent was also tested. Exposure assessments were made both by the environmental concentration and biological monitoring. CV and CS tests were carried out for all the subjects. VEP was measured for 21 exposed subjects who were considered to have impaired CV and CS. In the results, the color confusion index (CCI) values of the exposed subjects were significantly higher than that of the age-matched controls (P<0.01). Their CS values were significantly lower than those in the controls at spatial frequencies of 6 and 12 cycles per degree (cpd) (P<0.01 and <0.05, respectively). A significant correlation between the concentration of urinary methylhippuric acid and contrast sensitivity was found by a multiple regression analysis (P<0.05). CCI showed a negative correlation at all spatial frequencies of CS in a simple regression analysis, no abnormal data were found by the VEP test in the exposed subjects who were found to have impaired CV and CS. The results suppose that a low concentration of the mixed organic solvents might affect the retina and optic nerve. However, it needs to be further researched if such an impact affects the Brodmann's areas of visual cortex in the brain.
Adult↗
Color discrimination impairment in workers exposed to mercury vapor.
OBJECTIVE: To study color discrimination impairment in workers exposed to elemental mercury (Hg) vapor. SUBJECTS: Twenty-four male workers from a chloralkali plant exposed to Hg vapor, aged 42+/-9.8 years, duration of exposure 14.7+/-9.7 years, were examined. The 8h TWA air-borne Hg concentration in workplace was 59 microg/m(3); mean Hg urinary excretion (HgU) was 20.5+/-19.3 microg/g creatinine; mean Hg urinary excretion after the administration of a chelating agent, sodium 2,3-dimercapto-1-propane-sulfonate (DMPS), was 751.9+/-648 microg/48h. Twenty-four age- and gender-matched control subjects were compared. Visual acuity, alcohol intake, smoking habits, and history of diseases or drugs potentially influencing color vision were registered. METHODS: The Lanthony 15-Hue desaturated test (L-D15-d) was used to assess color vision. The results were expressed quantitatively as Bowman's Color Confusion Index (CCI), and qualitatively according to Verriest's classification of acquired dyschromatopsias. RESULTS: The CCI was significantly higher in the exposed group than in the control (mean CCI 1.15 versus 1.04; P=0.04). The proportion of subjects with errorless performance on the Lanthony test was significantly lower in the Hg exposed group compared to referents (52% versus 73%; P=0.035). The exposed group showed higher frequency of type III dyschromatopsias (blue-yellow confusion axis) in comparison with the control group (12.5% versus 8.3%), however, the difference did not reach statistical significance. Multiple regression did not show any significant relationship between the CCI, and age, alcohol consumption, or measures of exposure. CONCLUSION: In agreement with previous studies by Cavalleri et al. [Toxicol. Lett. 77 (1995) 351; Environ. Res. Sec. A 77 (1998) 173], the results of this study support the hypothesis that exposure to mercury vapor can induce sub-clinical color vision impairment. This effect was observed at an exposure level below the current biological limit for occupational exposure to mercury. This raises doubts on the actual protection afforded by this limit concerning the effect of mercury on color vision.
Adult↗
Color vision impairment in workers exposed to neurotoxic chemicals.
Recent research shows that occupational exposure to several solvents, metals and other industrial chemicals can impair color vision in exposed workers. Occupation-related color vision impairment usually results in blue-yellow color discrimination loss or, less frequently, a combination of blue-yellow and red-green loss. The eyes may be unequally involved, and the course is variable depending on exposure and other factors. The pathogenesis of occupational color vision loss has not been elucidated; it may be due to, e.g. a direct action of neurotoxins on receptors, possibly on the cone's membrane metabolism, and/or to an interference with neurotransmitters within the retina. Other possible pathogenetic mechanisms, such as a direct effect to the optic nerve, have also been suggested. Occupational color vision loss is usually sub-clinical, and workers are unaware of any deficit. It can be assessed using sensitive tests, such as the Farnsworth-Munsell 100 Hue (FM-100) or the Lanthony D-15 desaturated panel (D-15 d). The latter is the most widely used for studies in groups of exposed workers, and offers the possibility of a quantitative evaluation of the results by calculation of the Bowman's Color Confusion Index (CCI), or of the Vingrys' and King Smith's Confusion Index (CI). Other advantages of D-15 d are the possibility to perform the test directly at the workplace, and the reproducibility when performed in standardized conditions. In most cases, occupation-related color vision impairment is correlated to exposure levels, and has often been observed in workers exposed to environmental concentrations below the current occupational limit proposed by the ACGIH. Progression with increasing cumulative exposure has been reported, while reversibility is still discussed. Acquired color vision impairment related to occupational exposure to styrene, perchloroethylene (PCE), toluene, carbon disulfide, n-hexane, solvent mixtures, mercury and some other chemicals are discussed. Results show that color vision testing should be included in the evaluation of early neurotoxicity of chemicals in exposed workers. The D-15 d would be useful in the surveillance of workers exposed to solvents and other chemicals toxic to the visual system.
Animals↗
[Congenital achromatopsia: electroretinogram in early diagnosis].
PURPOSE: Achromatopsia is a hereditary disease responsible for congenital low vision. Patients present with nystagmus, abnormal visual behavior or photophobia. Only the electroretinogram (ERG) can confirm the diagnosis in infants. PATIENTS AND METHODS: Thirty children referred for nystagmus or low vision were included in this retrospective study. A complete ophthalmological examination, an ERG and when possible a color vision test (Ishihara, Farnsworth 15 Hue test) was done. A Ganzfeld ERG was performed in accordance with ISCEV standards in patients more than 6 years of age. In younger patients, a simplified method using electroluminescent diode stimulation was used and a comparative ERG in accordance with ISCEV standards was performed when the patients were old enough. RESULTS: The ERG response was identical in children and adults. It confirmed the diagnosis of achromatopsia: the scotopic components obtained in dark adapted conditions were normal, (scotopic a-wave, b2 wave). The photopic components, recorded in light-adapted conditions, in order to inhibit the scotopic response (photopic wave, b1 wave), were not recordable. The color vision tests confirmed color blindness; however, in some patients color denomination was correct. CONCLUSION: The simplified ERG procedures performed in our series were reliable in detecting achromatopsia. However, it may not be sufficient to discriminate complete from incomplete achromatopsia.
Adolescent↗