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PubMed1995

Signal standardization of the secondary ion mass spectrometry (SIMS) microscope for quantification of halogens and calcium in biological applications.

The secondary ion mass spectrometry (SIMS) microscope is able to map chemical elements in tissue sections. Although absolute quantification of an element remains difficult, a relative quantitative approach is possible for soft tissue by using carbon (12C) as an internal reference present at large homogeneous and constant concentration in specimen and embedding resin. In this study, this approach is used to standardize the signal of an SIMS microscope for the quantification of halogens (9F-, 35Cl- and 79Br-) and calcium (40Ca+). Standard preparation was determined based on homogeneity and stability criteria by molecular incorporation (halogens) or mixing (calcium) in methacrylate resin. Standard measurements were performed by depth analysis on areas of 8 microns (halogens) and 150 microns (calcium) in diameter for 10-30 min, under Cs+ (halogens) or Ox+ (calcium) bombardment. Results obtained from 100-120 measurements for each standard dilution show that the relationship between the signal intensity measured and the elemental concentration (micrograms/mg of wet tissue or mM) is linear in the range of biological concentrations. This quantitative approach was applied firstly to bromine of the 5-bromo-2'-deoxyuridine (BrdU) used as nuclear marker of rat hepatocytes in proliferation. The second model concerns depletion of calcium concentration in cortical compartment in Paramecium tetraurelia during exocytosis. Then signal standardization in SIMS microscopy allows us to correlate quantitative results with those obtained from other methods.

Animals↗

PubMed1976

Peroxidase-catalyzed halogenation.

Peroxidase-catalyzed halogenation reactions have been established as being important in the biosynthesis of the hormone thyroxine and in biological defense mechanisms. Recently these reactions have been recognized as valuable tools for the study of proteins as well as their arrangement in macromolecular structures. The pathways of peroxidase catalyses can be accommodated within the framework of the classical Chance-George mechanism. This implies that the initial steps of the reaction invariably involve oxidation of peroxidases by peroxides--and that the resulting derivative, compound I, is the oxidant of the halide ions. Such reactions may result either in the formation of hypohalous acids, or in halogenation of the enzyme apoprotein, followed by transhalogenation to substrate for halogenation. Chloro- and myeloperoxidases catalyze oxidation of all halide ions, except F-; oxidation of bromide and iodide is mediated by lactoperoxidase, but horseradish peroxidase only oxidizes iodide. All of the above enzymes except horseradish will oxidize the pseudo halide thiocyanate. The origins of this differentiation remain to be defined, but they presumably reflect significant variation in oxidation potential of different peroxidase-peroxide derivatives, rather than constraints on the peroxidase-donor interactions. As pointed out above, halogenation of the amino acids tyrosine and histidine or these residues in proteins can take place on the enzyme. This makes lactoperoxidase-catalyzed iodination selective. The amino acid residues in proteins that are iodinated depend not only on reactivity of the amino acid residue but also on its geometric location. Thus lactoperoxidase-catalyzed iodination can be a useful tool in the study of protein structure and function. It is also useful in establishing the geometric position of proteins within macromolecular structures. Thyroid peroxidase catalyzes iodination of thyroglobulin and is involved in a second important step, the coupling of the iodotyrosines to form thyroxine or triiodothyronine. A proposed mechanism for this reaction suggests that the oxidation is mediated by the iodoenzyme derivative mentioned above followed by a prototropic rearrangement and scission to form the ether bound of thyronine and a serine residue on thyroglobulin.

Amino Acids↗

PubMed1989

Development and validation of in vitro induction assays for toxic halogenated aromatic mixtures: a review.

Halogenated aromatic industrial compounds, typified by the polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) have been identified as residues in almost every component of the global ecosystem. Risk assessment of the complex mixtures of halogenated aromatics found in environmental samples is complicated by analytical problems and the lack of toxicological information on individual compounds and mixtures. Research in our laboratory has focused on the development and vadidation of the in vitro aryl hydrocarbon hydroxylase (AHH) induction assay in rat hepatoma H-4-II E cells in culture for quantitating individual toxic halogenated aryl hydrocarbons and their mixtures. For several PCB, PCDD, PCDF congeners, their mixed bromo/chloro analogs and reconstituted mixtures there was an excellent linear correlation between their -log ED50 values for AHH induction in rat hepatoma cells and their -log ED50 values for in vivo hepatic microsomal AHH induction, inhibition of body weight gain and thymic atrophy in the rat. It has also been shown for selected compounds that there was a good correlation between their in vitro AHH induction potencies and their effects in guinea pigs (AHH induction, inhibition of body weight gain) and mice (immunotoxicity). This assay system has been utilized to quantitative the "2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents" present in extracts from diverse sources including fly ash from a municipal incinerator and pyrolyzed brominated flame retardants which contain a complex mixture of halogenated dibenzo-p-dioxins and dibenzofurans.

Animals↗

PubMed1999

Synthesis and pharmacological evaluation in mice of halogenated cannabidiol derivatives.

Six halogenated derivatives of cannabidiol (CBD, 1) substituted on the aromatic ring at the 3' and/or 5' position, 3'-chloro- (2), 3',5'-dichloro- (3), 3'-bromo- (4), 3',5'-dibromo- (5), 3'-iodo- (6) and 3',5'-diiodo-CBD (7) were synthesized and their pharmacological effects of barbiturate-induced sleep prolongation, anticonvulsant effects and locomotor activity were evaluated by intravenous (i.v.) injection in mice. 2 (10 mg/kg, i.v., 69 +/- 10 min) significantly prolonged pentobarbital-induced sleeping time by 3.1-fold, compared to control (22 +/- 2 min), although other 1 derivatives used did not significantly affect the sleeping time. 2, 4 and 6 (10 mg/kg, i.v.) significantly prolonged hexobarbital-induced sleeping time by 2.0-, 2.0- and 2.3-fold, respectively, compared with control (52 +/- 5 min). On the other hand, 1 and all halogenated derivatives did not significantly prolong barbital-induced sleeping time. The monohalogenated derivatives, 2, 4 and 6 were able to prolong pentobarbital and hexobarbital-induced sleeping time, although the dihalogenated derivatives, 3, 5 and 7 did not exhibit a prolongation of the sleeping time. All halogenated derivatives of 1 except for brominated derivatives (2, 3, 6, 7) tended to prolong tonic seizure latency induced by pentylenetetrazol. 1 and its halogenated derivatives did not exhibit any prolongation of seizure latency induced by picrotoxin or strychnine. Maximal electroshock test demonstrated that 1 and 4 exhibited almost the same potency in their anticonvulsant effects, although other 1 derivatives 2, 3, 5, 6 and 7 did not show significant effect up to a dose of 63 mg/kg, i.v. The ED50 values (mg/kg, i.v.) of 1 and 4 were 38 and 44, respectively. 1 and 4 also showed anticonvulsant effect in minimal and maximal electroshock-threshold tests. 2, 4 and 6 tended to decrease the total distance (horizontal activity) and number of rearings (vertical activity) of mice, whereas 3, 5 and 7 tended to increase the number of rearings. However, the effects of all derivatives were not statistically significant from the control. 2 and 4 were the most potent derivatives on pharmacological activities among the synthetic cannabinoids examined in the present study. These results indicate that monohalogenation of 1 leads to some modification of the pharmacological profile of CBD.

Animals↗

PubMed1975

Exposure to halogenated hydrocarbons in the indoor environment.

The indoor environment has frequently been ignored as a significant source of exposure to air pollutants. To date there are a number of documented examples of levels of indoor air pollutants greatly exceeding those levels which commonly occur in the outdoor environment. Among these instances are airborne buildup of polynuclear aromatics and cadmium from cigarette smoke, lead from burning candles, and vinyl chloride from use of aerosols containing this substance as a propellant. These examples suggest that there may be additional sources of indoor air pollutants, particularly halogenated hydrocarbons from aerosol products, which have heretofore not been generally recognized as important. The present paper endeavors to review those instances where halogenated hydrocarbons in the indoor air environment may build up to concentrations of potential public health concern. These considerations may be especially relevant in future years as increasing efforts are being made to insulate buildings more efficiently as a means to conserve energy. The available data strongly suggest that halogenated hydrocarbons are an important class of air pollutants in the indoor environment and that their presence in the outdoor environment should also be carefully examined. In this regard, halogenated hydrocarbons in the outdoor environment may also contaminate indoor air spaces.

Aerosol Propellants↗

PubMed1985

Biochemical studies on the metabolic activation of halogenated alkanes.

This paper reviews recent investigations by Slater and colleagues into the metabolic activation of halogenated alkanes in general and carbon tetrachloride in particular. It is becoming increasingly accepted that free radical intermediates are involved in the toxicity of many such compounds through mechanisms including lipid peroxidation, covalent binding, and cofactor depletion. Here we describe the experimental approaches that are used to establish that halogenated alkanes are metabolized in animal tissues to reactive free radicals. Electron spin resonance spectroscopy is used to identify free-radical products, often using spin-trapping compounds. The generation of specific free radicals by radiolytic methods is useful in the determination of the precise reactivity of radical intermediates postulated to be injurious to the cell. The enzymic mechanism of the production of such free radicals and their subsequent reactions with biological molecules is studied with specific metabolic inhibitors and free-radical scavengers. These combined techniques provide considerable insight into the process of metabolic activation of halogenated compounds. It is readily apparent, for instance, that the local oxygen concentration at the site of activation is of crucial importance to the subsequent reactions; the formation of peroxy radical derivatives from the primary free-radical product is shown to be of great significance in relation to carbon tetrachloride and may be of general importance. However, while these studies have provided much information on the biochemical mechanisms of halogenated alkane toxicity, it is clear that many problems remain to be solved.

Aerobiosis↗

PubMed2002

A comparison of polymerization by light-emitting diode and halogen-based light-curing units.

BACKGROUND: Light-emitting diode, or LED, technology provides certain advantages over halogen-based light polymerization of resin-based composites. The authors investigated the adequacy of cure of LED light-curing units, or LCUs. METHODS: The authors used two halogen-based light-curing units (Optilux 400 and 501, Demetron Research Corp., Danbury, Conn.) and two commercially available LED LCUs (LumaCure, LumaLite, Spring Valley, Calif., and VersaLux, Centrix, Shelton, Conn.) to polymerize top surfaces of hybrid (Filtek Z-250, 3M, St. Paul, Minn.) and microfilled (Renamel, Cosmedent, Chicago) resin-based composite specimens. Specimens were indented on their top and bottom surfaces with a Knoop hardness tester and measured for hardness. Bottom:top hardness ratios determined the percentage of cure. The authors separated the data into eight groups (two composites cured with four different lights) with 15 observations per group, for a total sample size of 120. RESULTS: The authors compared composites and curing lights by a two-way analysis of variance, and results indicated significant main effects. The main effect of composite was statistically significant (P < .0001) when microfilled composite was compared with hybrid composite, regardless of curing light, for all top and bottom hardness measurements, with the hybrid producing much higher hardness measurements overall. The main effect of light was significant as well (P < .0001), regardless of composite type, with the two halogen-based lights producing harder top and bottom composite surfaces than the two LED LCUs. CONCLUSIONS: The light output of commercially available diodes for resin-based composite polymerization still requires improvement to rival the adequacy of cure of halogen-based LCUs. Additional studies are necessary. CLINICAL IMPLICATIONS: Commercially available LED LCUs were introduced just in the past year. However, they may not adequately polymerize resin-based composites, which can lead to restoration failures and adverse pulpal responses to unpolymerized monomers.

Analysis of Variance↗

PubMed2000

Enzymatic halogenation catalyzed via a catalytic triad and by oxidoreductases.

During the search for haloperoxidases in bacteria we detected a type of enzymes that catalyzed the peroxide-dependent halogenation of organic substrates. However, in contrast to already known haloperoxidases, these enzymes do not contain a prosthetic group or metal ions nor any other cofactor. Biochemical and molecular genetic studies revealed that they contain a catalytic triad consisting of a serine, a histidine, and an aspartate. The reaction they catalyze is actually the perhydrolysis of an acetic acid serine ester leading to the formation of peracetic acid. As a strong oxidizing agent the enzymatically formed peracetic acid can oxidize halide ions, resulting in the formation of hypohalous acid which then acts as the actual halogenating agent. Since hypohalous acid is also formed by the heme- and vanadium-containing haloperoxidases, enzymatic halogenation catalyzed by haloperoxidases and perhydrolases in general lacks substrate specificity and regioselectivity. However, detailed studies on the biosynthesis of several halometabolites led to the detection of a novel type of halogenases. These enzymes consist of a two-component system and require NADH and FAD for activity. Whereas the gene for one of the components is part of the biosynthetic cluster of the halometabolite, the second component is an enzyme which is also present in bacteria from which no halometabolites have ever been isolated, like Escherichia coli. In contrast to haloperoxidases and perhydrolases the newly detected NADH/FAD-dependent halogenases are substrate-specific and regioselective and might provide ideal tools for specific halogenation reactions.

Catalysis↗

PubMed2006

Analysis of the microtensile bond strength to enamel of two adhesive systems polymerized by halogen light or LED.

With the development of composite resin polymerization techniques, LEDs were introduced to the market place. Based on the studied literature, the aim of this study was to evaluate, through microtensile testing, the bond strength to enamel of a composite resin associated to a conventional (multi-bottle) adhesive system or to a self etching primer adhesive system, polymerized by halogen light or LED (light emitting diode). Bovine teeth were divided into 4 groups with 10 teeth each (n = 10). Then the adhesives Scotchbond Multipurpose Plus (3M-ESPE) and Clearfil SE Bond (Kuraray) were applied following the manufacturers instructions. Both systems were polymerized for 10 s by halogen light (Degulux Soft Start-Degussa Hulls) set at 550 mW/cm(2) or by LED (Kerr Demetron) set at 600 mW/cm(2). The composite resin Filtek Z-250 was applied in four 1 mm increments with the aid of a square, condensation silicon, 5 mm x 5 mm matrix, and polymerized by either of light sources for 40 s. Scotchbond Multipurpose Plus polymerized by halogen light presented the highest bond strength values (39.69 +/- 7.07 MPa), and the other groups did not present statistically significant differences: Scotchbond Multipurpose Plus polymerized by LED (22.28 +/- 2.63 MPa), Clearfil SE Bond polymerized by halogen light (27.82 +/- 2.65 MPa) and by LED (22.89 +/- 5.09 MPa).

Adhesiveness↗

PubMed1994

Influence of the type of halogen substituent on in vivo and in vitro phase II metabolism of 2-fluoro-4-halophenol metabolites formed from 3-halo-fluorobenzenes.

1. The influence of a change in the type of halogen substituent on phase II metabolism of 2-fluoro-4-halophenol metabolites formed from 3-halo-fluorobenzenes was studied in vivo and in vitro using 19F nmr and spectroscopic assays. 2. The ratio of sulphation to glucuronidation of 2-fluoro-4-halophenol metabolites formed from 3-halofluorobenzenes decreased from 48 to 13 to 6 when the halogen substituent varied from fluorine to chlorine to bromine. 3. When the 2-fluoro-4-halophenols themselves were administered to the rats, the ratio of sulphation to glucuronidation was not affected by the type of halogen substituent at C4 and at a constant value of 0.6, i.e. significantly lower. 4. Kinetic data for P450 catalysed hydroxylation of the 3-halo-fluorobenzenes and for sulphation and glucuronidation of their 2-fluoro-4-halophenol metabolites were obtained from in vitro microsomal and cytosolic incubations. These data demonstrate that the effects of varying the halogen substituent on phase II metabolism of the 2-fluoro-4-halophenol metabolites can be mainly ascribed to an apparently decreased Km for the glucuronidation of the 2-fluoro-4-halophenols with a change in the halo substituent from fluorine to chlorine to bromine. 5. Results from calculations on electronic and structural characteristics of the three 4-halo-2-fluorophenols demonstrate that the best explanation for the decrease in the apparent Km of the glucuronidation from 2,4-difluoro- to 4-chloro-2-fluoro- to 4-bromo-2-fluorophenol might be an increase in the hydrophobicity of the phenol. An increase in the hydrophobicity of the phenol would provide an increased possibility for substrate accumulation in the hydrophobic membrane environment of the UDP-glucuronyltransferases, resulting in an apparently decreased Km.

Animals↗

PubMed1991

Biotransformation of halogenated compounds.

As a result of natural production and contamination of the environment by xenobiotic compounds, halogenated substances are widely distributed in the biosphere. Concern arises as a result of the toxic, carcinogenic, and potential teratogenic nature of these substances. The biotransformations of such halogenated substances are reviewed, with particular emphasis on the biocatalytic cleavage of the carbon-halogen bonds. The physiology, biochemistry, and genetics of the biological system involved in the dehalogenation reactions are discussed for three groups of organohalogens: (1) the haloacids, (2) the haloaromatics, and (3) the haloalkanes. Finally, the biotechnological applications of these microbial transformations are discussed. This includes prospects for their future application in biosynthetic processes for the synthesis of halogenated intermediates or novel compounds and also the use of such systems for the detoxification and degradation of environmental pollutants.

Bacteria↗

PubMed1993

Bioactivation of halogenated hydrocarbons by cytochrome P4502E1.

Numerous halogenated hydrocarbons of the alkane, alkene, and alkyne classes are metabolized by P450 enzymes to products that elicit cytotoxic and/or carcinogenic effects. Such halogenated hydrocarbons include anesthetics (e.g., halothane and enflurane) and industrial solvents (e.g., carbon tetrachloride, chloroform, and vinylidine chloride). Formation of reaction intermediates from these compounds occurs via P450-promoted dehalogenation, reduction, or reductive oxygenation, with certain hydrocarbons undergoing all three reaction types. Of the multiple forms of P450 present in liver microsomes, P4502E1 has been identified as the primary catalyst of hydrocarbon bioactivation in animals and, most likely, in humans as well. As hepatic concentrations of this P450 enzyme are highly inducible by ethanol and similar agents, prior exposure to 2E1-inducing compounds can play a pivotal role in halogenated hydrocarbon toxicity. Considering that metabolism governs the cytotoxicity and carcinogenicity of halogenated hydrocarbons, an understanding of the mechanism(s) underlying 2E1 induction in man becomes all the more important.

Anesthetics↗

PubMed2005

A new laboratory polymerizing apparatus equipped with halogen and metal halide light sources.

We developed a new laboratory polymerizing unit (Twinkle MIII: M3) equipped with different light sources (a metal halide and two halogen lamps) that could illuminate independently. This study introduced the structure of the curing unit and examined the curing depth of a representative indirect composite (Artglass). The composite material was cured with the following modes: 1) M3 - halogen only; 2) M3 - metal halide only; 3) M3 - both halogen and metal halide (HM); 4) conventional xenon; and 5) preliminary halogen. The results obtained from analysis of variances and post-hoc tests revealed that curing depth was affected significantly (p < 0.05) by both exposure mode and time, and that HM mode exhibited the most favorable curing performance (p < 0.05) among the curing units and polymerization modes. In conclusion, the M3 unit was found to be well suited to polymerizing the composite material tested.

Analysis of Variance↗

PubMed1991

Measurement of organic halogen compounds in urine as an indicator of exposure.

The report describes the measurement of urinary organic halogen compounds. The method is an application of the adsorbable organic halogen assay which is widely used for the analysis of industrial waste water and drinking water. It was found that this assay can be applied to human urine if the urine is pretreated to hydrolyze the mucins so as to cleave the neuraminic acid residues responsible for the high viscosity of these slimy proteins. The method was found to be sensitive down to 1 microgram of organic halogen/100 ml of urine. Fifty to 260 micrograms of organic halogen was measured in the night urine of healthy, occupationally unexposed volunteers. Since many toxic chemicals to which man may be exposed environmentally or occupationally are, in fact, halogen compounds, this assay may be used to monitor for human exposure.

Adolescent↗

PubMed2003

LED and halogen lights: effect of ceramic thickness and shade on curing luting resin.

The purpose of this study was to measure and compare the hardness of a light-cured luting resin cured under different shades and thicknesses of porcelain with a halogen and a light-emitting diode (LED) light. Square (11 mm x 11 mm) specimens of a commercially available porcelain with thicknesses of 1 mm and 2 mm were fabricated. Two shades of porcelain--A1 representing a high-value, low-chroma porcelain and C4 representing a low-value, high-chroma porcelain--were used to fabricate specimens. Composite luting resin, 0.5 mm in thickness, was placed under each porcelain specimen and light-cured for 30 or 60 seconds with LED or halogen light. The degree of polymerization of resin cement was determined by measuring the microhardness. The control group in this study was a 0.5-mm composite luting resin cured under clear Mylar matrix. No significant differences were recorded between surface hardness of control subgroups and LED subgroups cured for 30 or 60 seconds. A lower hardness value was recorded for 2-mm C4 porcelain cured for 30 and 60 seconds with the halogen light. Although a cumulative comparison of surface hardness revealed similar results for both lights, the LED light provided more consistent results than the halogen light.

Color↗

PubMedDate not supplied

Elution of leachable components from composites after LED and halogen light irradiation.

This study investigated the influence of curing lights and modes on the elution of leachable components from dental composites. Four LED/halogen curing lights (LED-Elipar Freelight [FL], 3M-ESPE and GC e-light [EL], GC; high intensity halogen-Elipar Trilight [TL], 3M-ESPE; very high intensity halogen-Astralis 10 [AS], Ivoclar Vivadent) were selected for this study. Pulse (EL1), continuous (FL1, EL2, TL1), turbo (EL3, AS) and soft-start (FL2, EL4, TL2) curing modes of the various lights were examined. A conventional continuous cure halogen light (Max [MX], Dentsply-Caulk) was used for comparison. Three composite (Z100, 3M-ESPE) specimens (6.5 mm in diameter and 1-mm thick) were made for each curing light-mode combination. After polymerization, the specimens were stored in air at 37 degrees C for 24 hours and incubated in acetonitrile at 37 degrees C for 24 hours. BisGMA and TEGDMA extracts were isolated by high performance liquid chromatography (HPLC). Data were subjected to analysis using one-way ANOVA/Scheffe's post-hoc test and Independent Samples t-test at significance level 0.05. The total monomer (BisGMA and TEGDMA) eluted ranged from 8.75 to 27.97 ppm for FL1 and AS, respectively. Significantly more unreacted monomers were leached from composites cured with all modes of EL and AS when compared to MX. No significant difference in the total monomer eluted was observed between the two modes of FL/TL and MX Although composites cured with EL2 released significantly less monomer than EL1, 3 and 4, no significant difference in the total monomer eluted was observed between the continuous and soft-start modes of FL and TL. The elution of leachable components from composites appears to be curing light specific rather than light source (LED or halogen) and curing mode specific.

Analysis of Variance↗

PubMed1991

Selectivity of ion permeability across ascending thin limb of Henle's loop: interaction of Cl- and other halogens with anion transport system.

In hamster ascending thin limb of Henle's loop (ATL) perfused in vitro, we examined halogen selective permeability and effects on Cl- transport. Relative permeabilities for halogens to sodium (PX/PNa) were determined by single salt dilution voltage. (PF/PNA, PCl/PNa, PBr/PNa and PI/PNa were 0.47 +/- 0.09, 3.23 +/- 0.22, 3.23 +/- 0.26, and 0.47 +/- 0.09, respectively. Simultaneous determination of 36Cl and 125I fluxes confirmed that addition of 10(-4) M 5-nitro-2-(3-phenyl-propylamino)-benzoate (NPPB), a Cl- channel blocker, to the bath decreased the flux coefficient for 36Cl (10(-7) cm2/s) from 67.0 +/- 11.7 to 29.5 +/- 7.9 without affecting that for 125I. NPPB also reduced both PCl/PNa and PBr/PNa from 2.67 +/- 0.20 to 0.95 +/- 0.12 and from 2.33 +/- 0.24 to 1.32 +/- 0.12, respectively. Addition of 100 mM Cl- or I- decreased 36Cl flux coefficient from 124.8 +/- 14.3 to 87.7 +/- 13.0 or to 41.0 +/- 11.6 without affecting that for 125I. All other halogens and SCN- also exhibited inhibitory effects on 36Cl flux. These findings support the hypothesis that the putative Cl- channel in the ATL is highly permeable to both Cl- and Br- but less permeable to I-, F-, and SCN-. They suggest that there are at least two functionally distinct components in the process of Cl- transport across the ATL, the binding site and the selective barrier. All halogens may compete against Cl- at the binding site.

Animals↗

PubMed1991

[Value of very low voltage halogen lighting of desaturated panel D 15 test in established glaucoma].

The colour vision of a first group of glaucomatous patients was tested with the desaturated Panel D 15 test, first illuminated by a 300 lux Macbeth lamp, then with a very low voltage 1000 lux halogen lamp. In addition to the recording of 80% cases of dyschromatopsia, in line with previously published data, we demonstrated a great number (33.3%) of red-green axis anomalies under Macbeth light and, paradoxically, even more under halogen light (53.3%). To explain this high percentage of red-green axes under halogen light, we discuss the influence of luminance and emission spectrum of the light source. We conclude that the use of high luminance halogen light is capable of revealing concealed Verriest type II dyschromatopsias probably due to a specific fragilisation of the red-green channels induced by the glaucoma disease. This original colour vision testing procedure applied on established glaucomatous patients enabled us to easily obtain a factor of severity in the course of the disease.

Adult↗