Tritan Axis Research Articles

Color‐space distortions following long‐term occupational exposure to mercury vapor

Color vision was examined in subjects with long-term occupational exposure to mercury (Hg) vapor. The color vision impairment was assessed by employing a quantitative measure of distortion of individual and group perceptual color spaces. Hg subjects (n = 18; 42.1 ± 6.5 years old; exposure time = 10.4 ± 5.0 years; time away from the exposure source = 6.8 ± 4.6 years) and controls (n = 18; 46.1 ± 8.4 years old) were examined using two arrangement tests, D-15 and D-15d, in the traditional way, and also in a triadic procedure. From each subject's 'odd-one-out' choices, matrices of inter-cap subjective dissimilarities were derived and processed by non-metric multidimensional scaling (MDS). D-15d results differed significantly between the Hg-group and the control group (p < 0.05), with the impairment predominantly along the tritan axis. 2D perceptual color spaces, individual and group, were reconstructed, with the dimensions interpreted as the red-green (RG) and the blue-yellow (BY) systems. When color configurations from the Hg-group were compared to those of the controls, they presented more fluctuations along both chromatic dimensions, indicating a statistically significant difference along the BY axis. In conclusion, the present findings confirm that color vision impairments persist in subjects that have received long-term occupational exposure to Hg-vapor although, at the time of testing, they were presenting mean urinary concentration within the normal range for non-exposed individuals. Considering the advantages of the triadic procedure in clinical evaluation of acquired color vision deficiencies, further studies should attempt to verify and/or improve its efficacy.

Effects on colour discrimination during long term exposure to high altitudes on Mt Everest

AimTo investigate changes in colour discrimination as a result of chronic hypoxic exposure induced by extreme altitudes (above 8000 m) during an expedition to Mt Everest.MethodsColour discrimination thresholds for tritan,...

Latency characteristics of the short-wavelength-sensitive cones and their associated pathways

There are many distinct types of retinal ganglion and LGN cells that have opponent cone inputs and which may carry chromatic information. Of interest are the asymmetries in those LGN cells that carry S-cone signals: in S-ON cells, S+ signals are opposed by (L + M) whereas, in many S-OFF cells, L+ signals are opposed by (S + M), giving -S + L - M (C. Tailby, S. G. Solomon, & P. Lennie, 2008). However, the S-opponent pathway is traditionally modeled as +/-[S - (L + M)]. A phase lag of the S-cone signal has been inferred from psychophysical thresholds for discriminating combinations of simultaneous sinusoidal modulations along +/-[L - M] and +/-[S - (L + M)] directions (C. F. Stromeyer, R. T. Eskew, R. E. Kronauer, & L. Spillmann, 1991). We extend this experiment, measuring discrimination thresholds as a function of the phase delay between pairs of orthogonal component modulations. When one of the components isolates the tritan axis, there are phase delays at which discrimination is impossible; when neither component is aligned with the tritan axis, discrimination is possible at all delays. The data imply that the S-cone signal is delayed by approximately 12 ms relative to (L - M) responses. Given that post-receptoral mechanisms show diverse tuning around the tritan axis, we suggest that the delay arises before the S-opponent channels are constructed, possibly in the S-cones themselves.

Color Vision in the Tritan Axis Is Predominantly Affected at High Altitude

The purpose of this study was to evaluate color vision during high altitude mountain climbing by applying the Mollon-Reffin Minimalist test to 14 climbers, all of whom were participating in the expedition to Ama Dablam (6,812 m) in Nepal. Before leaving for Nepal (at 300 m), all 28 eyes showed normal color vision in all 3 axes. At 1,300 m, 100% of eyes showed normal color vision in the protan and deutan axes, while 25% showed minimally reduced color discrimination in the tritan axis. At 4,000 m, 100% showed normal deutan axis, 4% minimally reduced protan axis, and 72% minimally reduced tritan axis discrimination. At 5,400 m 100% of eyes tested showed normal protan and deutan axis discrimination, while 75% showed minimally and 25% moderately reduced tritan axis discrimination. Back home at 300 m 3 days after return, 100% showed normal deutan, 4% minimally reduced protan, and 38% minimally reduced tritan axis discrimination. One year later, all eyes showed normal color vision in all three axes. Changes in tritan axis discrimination correlated well with increased heart rate (r = 0.69; p = 0.0001) and decreased oxygen saturation (r = 0.71; p = 0.001) at high altitude. This study shows that the tritan color vision axis is predominantly affected at high altitude, but that this reduced color discrimination is transient.

Independent patterns of damage within magno-, parvo- and koniocellular pathways in Parkinson's disease

Sensory deficits have been documented in Parkinson's disease, in particular within the visual domain. However, ageing factors related to the brain and to neural and non-neural ocular structures could explain some of the previously reported results, in particular the claimed impairment within the koniocellular pathway. This study addressed visual impairment attributable to the magno- (luminance), parvo- (red-green) and koniocellular (blue-yellow) pathways in a population of Parkinson's disease patients. To avoid potentially confounding factors, all subjects underwent a full neurophthalmological assessment which led to exclusion of subjects with increased intraocular pressure, diabetes even in the absence of retinopathy, and ocular abnormalities (from a total of 72 patients' eyes, 12 were excluded). Both parvo- and koniocellular pathways were studied by means of contrast sensitivity (CS) measurements along protan, tritan and deutan axes and also by fitting chromatic discrimination ellipses using eight measured contrast axes. Magnocellular function was assessed, using stimuli that induce a frequency doubling illusion, in 17 locations in the fovea and periphery. Achromatic (luminance modulation) thresholds were significantly higher in Parkinson's disease both in foveal and peripheral locations. A significant impairment was observed along protan and deutan axes, but only marginally along the tritan axis. These results were corroborated by a significant elongation of chromatic discrimination ellipses in our Parkinson's disease group. Correlation analysis showed that achromatic and chromatic CS measures were independent, which implies that multiple visual pathways are affected independently in Parkinson's disease. Magnocellular impairment was significantly correlated with age and disease stage, in contrast to the measured chromatic deficits. We conclude that in Parkinson's disease, independent damage occurs in the early magno- and parvocellular pathways. Furthermore, traditional koniocellular probing strategies in Parkinson's disease may be confounded by ageing factors, which may reconcile the previously reported controversial findings concerning chromatic impairment in Parkinson's disease.

Aspects of the diagnosis and treatment of glaucoma

Glaucoma is one of the most common causes of blindness in the world, and it is important that screening tests as well as treatment possibilities are improved continuously. A reliable but more rapid screening test than those already available would be of great interest. In addition, new and more effective treatment options would be most valuable. The aims of the present thesis were to evaluate the reliability of a new and rapid peripheral colour contrast sensitivity test as a tool for glaucoma screening and to gain more information on latanoprost, a recently developed prostaglandin analogue, in glaucoma treatment Colour contrast sensitivity was analysed with a system described by Arden and co-workers, using a computer controlled colour monitor. The test objects for the central test were letters of standard optotype subtending a visual angle of 3°. For the peripheral test, the test object was a colour contrasting annulus concentric with a fixation spot. The annulus had a radius of 12.5° in the extramacular field and a width of 1°. The colour contrast of the letter or the annulus in relation to the background could be changed, and a colour contrast threshold value could be obtained in the protan, deutan and tritan colour axes. In a study of glaucoma patients, ocular hypertensive patients and normals, the peripheral colour contrast sensitivity test was found to distinguish the glaucoma patients from the normals. However, it was difficult to find a reliable cut-off point if the test is to be used as a screening test. In a five-year prospective study of ocular hypertensive patients, the peripheral colour contrast sensitivity test could not clearly predict which patients would develop glaucoma and which would not, given that the Glaucoma Hemifield Test is used as the golden standard. A change over time in the protan axis may, however, indicate glaucoma development. For a test to be used in glaucoma screening, it is necessary to know whether other common eye diseases such as diabetes and cataract affect the outcome. Therefore, the influence of diabetes and cataract on peripheral and central colour contrast sensitivity was also studied. Diabetes type II was found to affect both peripheral and central colour contrast sensitivity, the tritan axis being the most affected one. For the tritan axis, the central colour contrast sensitivity seemed to correlate well with the degree of diabetic retinopathy, indicating the possibility of a new functional test of diabetic retinopathy. Cataract, even moderately developed, affected both peripheral and central colour contrast sensitivity. Central colour contrast sensitivity seemed to be poorer in pseudophakic eyes than in normal eyes. Thus, both diabetes type II and moderate to severe cataract must be considered if the colour contrast sensitivity test is to be used for glaucoma screening. The choice of material for the IOL may also be of importance for postoperative central colour contrast sensitivity. The prostaglandin analogue latanoprost effectively reduces the IOP at the original concentration of 0.005%. However, several patients need additional treatment. Therefore, the effect of pilocarpine in combination with latanoprost was studied. When pilocarpine was added to latanoprost, there was an additional reduction in the intraocular pressure (IOP) (7.4%), and when latanoprost was added to pilocarpine the reduction was even more pronounced (14.2%). Therefore, it seems that latanoprost and pilocarpine can be combined in glaucoma treatment. In certain eyes, an increased iris pigmentation was seen as a side-effect of latanoprost. This side-effect may be dose-dependent. Therefore, the original concentration of 0.005% was compared to a lower concentration, 0.001%. Latanoprost 0.005% was more effective than latanoprost 0.001% in reducing the IOP. However, the lower concentration was sufficiently effective to have a potential for clinical use in many patients. Latanoprost 0.005% gave an IOP reduction of 35% after four weeks of treatment, which was in agreement with earlier results. The lower concentration was, however, surprisingly effective and gave an IOP reduction of 27.7%. This thesis is based on the following papers:

Colour contrast sensitivity in ocular hypertension. A five-year prospective study.

To evaluate a peripheral colour contrast sensitivity test as a tool for early diagnosis of glaucoma in a five-year prospective study. Peripheral colour contrast sensitivity was measured with a computer graphics system developed by Arden et al. The test colours were varied along the protan, deutan and tritan colour confusion axes on a scale from 0 to 100 percentage units. Fifty-five ocular hypertensive (OH) patients examined with the colour contrast test, stereoscopic photography of the optic discs, and measurements of visual fields (Humphrey 24-2 glaucoma hemifield test (GHT)) in 1994, were re-examined after five years. Ten patients were 'outside normal limits' in the GHT at follow-up. This group of 10 patients did not differ in colour contrast thresholds at the test in 1994 from the 45 who were still 'normal' (or 'borderline') at follow-up. Neither were there proportionally more patients with GHT 'outside normal values' for the patients with high colour contrast thresholds (> 30% units) in 1994 regarding any of the three colour axes. As judged from patient files, 27 patients had developed glaucoma during follow-up. Although there were differences between these 27 glaucoma patients and the remaining OH group at the colour contrast test in 1994, these differences did not reach statistical significance for any of the colour axes (largest difference in the tritan axis: 6.2% units, P = 0.0745). At follow-up, however, there was a significant difference in colour contrast for the protan axis between the clinical glaucoma group and the OH group (6.7% units, P = 0.0105). The method used for colour contrast measurement did not reveal glaucomatous changes before conventional perimetry (Humphrey 24-2, GHT). Neither did it predict the patients who, in our clinic, subsequently developed glaucoma during a five-year period. A change over time in colour contrast in the protan axis for an OH patient may, however, indicate glaucoma development.

Melanoma-associated retinopathy: screening for melanoma-associated retinopathy in patients with cutaneous malignant melanoma

Purpose: Melanoma-associated retinopathy (MAR) is a paraneoplastic retinopathy that develops in some patients with cutaneous malignant melanoma (CMM).The syndrome is identified by, and possibly caused by, antibodies reactive with retinal depolarizing bipolar cells. CMM patients lacking indications of vision problems are not usually routinely screened for melanoma-induced retinal hypersensitivity, but may have undergone similar sensitization without losing tolerance or may be in the early stages of MAR. The purpose of this study was to look into the possibility that subclinical and immunologic indications of MAR appear in CMM patients without recognized retinopathies. Methods: Twenty-nine CMM patients (stages II-IV), being treated at the Department of Dermatology (The Saarland University Hospital), were screened to detect abnormalities suggestive of MAR. Our assessment included exploration of ophthalmologic history, ophthalmologic examination, electrophysiology, nyctometry, perimetry, testing of color vision, and serum examination for antiretinal autoantibodies. Parameters for diagnosing MAR were (1) reduced scotopic b-wave amplitude, (2) reduced contrast sensitivity in nyctometry, (3) abnormalities in perimetry, and (4) the identification of antiretinal antibodies, especially against the retinal bipolar cell layer. Results: Two patients had to be excluded due to either bad compliance (n = 1) or a clouding of the media (n = 1). Six of the remaining 27 patients were found to exhibit indications of MAR, showing abnormal results in all of the clinical examinations 1-3. Three of these six patients produced antibodies reactive with ocular tissue, including retinal bipolar cells. These three patients were accordingly classified as affected by MAR. These findings indicate a prevalence of MAR in approximately 10% of the study group. Eighteen of the remaining patients produced abnormal results in at least one of the evaluations for MAR. Patients with MAR-suspicious signs frequently had abnormalities in the Farnsworth Panel D15 tests, mostly in the tritan axis or involving all three color axes at the same time. Conclusions: MAR is widely considered to be a rare, immune-mediated paraneoplastic syndrome. Our screening for indications of MAR in CMM patients identified a much higher prevalence than expected. Impaired color vision in a CMM patient indicates the need for MAR screening.

Analysis of discrimination threshold on the tritan axis

Discrimination thresholds on the tritan axis were obtained for an extensive group of 66 stimuli: in some of the stimuli, S-cone trolands were held constant by keeping the product of the S-cone excitation level and the luminance unchanged, while in others only the luminance was changed to establish various S-cone troland values. These thresholds depended clearly on the S-cone value of the stimuli, while they remained almost constant against the retinal illumination. Thus, we noted that the excitation of the L - 2M channel had practically no influence over the discrimination threshold on the tritan axis, although this independence of delta S from L - 2M was not so obvious when the S value was high. With our data, we performed different fits, and found that the fit including the terms S, (L - 2M) and (L + M) adapted better to our results.

Analysis of discrimination threshold on the tritan axis

Discrimination thresholds on the tritan axis were obtained for an extensive group of 66 stimuli: in some of the stimuli, S-cone trolands were held constant by keeping the product of the S-cone excitation level and the luminance unchanged, while in others only the luminance was changed to establish various S-cone troland values. These thresholds depended clearly on the S-cone value of the stimuli, while they remained almost constant against the retinal illumination. Thus, we noted that the excitation of the L−2M channel had practically no influence over the discrimination threshold on the tritan axis, although this independence of ΔS from L−2M was not so obvious when the S value was high. With our data, we performed different fits, and found that the fit including the terms S, (L−2M) and (L+M) adapted better to our results.

Ocular haemodynamics and colour contrast sensitivity in patients with type 1 diabetes

BACKGROUNDThere is evidence that altered ocular blood flow is involved in the development and progression of diabetic retinopathy. However, the nature of these perfusion abnormalities is still a matter of...

Autosomal dominant cone–rod retinal dystrophy (CORD6) from heterozygous mutation of GUCY2D, which encodes retinal guanylate cyclase

ObjectiveTo describe the clinical features of autosomal dominant cone–rod retinal dystrophy (CRD) in a British family mapping to chromosome 17p12-p13 (CORD6), with a heterozygous mutation (Glu837Asp/Arg838Ser) of GUCY2D. DesignA prospective, clinical family survey. PatientsTen affected members of a family with autosomal dominant CRD. MethodsFull clinical examinations were undertaken. Selected affected family members underwent electrophysiologic evaluation, scotopic static perimetry, dark adaptometry, and color vision assessment. Main outcome measuresClinical appearance and electroretinographic responses. ResultsTypical clinical and electroretinographic features of childhood-onset CRD were recorded. In addition, moderate myopia and pendular nystagmus were seen in affected individuals. Color vision assessment in the youngest affected individual showed no color discrimination on a tritan axis, but retention of significant red–green discrimination. Electronegative electroretinogram responses were seen on electrophysiology in the only young family member examined. ConclusionsThe phenotype associated with GUCY2D CRD is clinically distinct from that associated with other dominant CRD loci. Unusual electroretinographic responses may indicate that this mutation of GUCY2D is associated with early defects in photoreceptor synaptic transmission to second-order neurons.

Measuring Short-Wavelength–Sensitive Cone Discrimination Thresholds Using Pseudoisochromatic Figures Displayed on a Color Monitor

To simplify the testing of short-wavelength–sensitive (SWS) cone function in the clinic. SWS-cone discrimination thresholds were measured along the tritan axis using pseudoisochromatic figures displayed on a color monitor. A circular 6° field, containing spatially discrete patches of varying sizes and luminances, was presented on a background. A subset of patches formed the target patch in the shape of a C. Eight subjects with normal color vision reported the direction of the gap in the C using a cursor controlled by a joystick. Data were expressed in units of SWS-cone trolands. SWS-cone discrimination threshold increased slowly as the SWS-cone trolands of the starting chromaticity increased. The dependence of the threshold on the SWS-cone activation level was similar to literature reports of chromatic discrimination measured with conventional paradigms. The advantages of this method: (a) It is a simple intuitive task for patients. (b) The paradigm can be implemented with an 8-bit/gun color monitor. (c) The test avoids the need to define equiluminance for the individual patient before the color test is administered. This method can provide a useful technique for measuring SWS-cone function in a clinical population.

Rods affect S-cone discrimination on the Farnsworth–Munsell 100-hue test

Rod influence on hue discrimination was assessed by the Farnsworth–Munsell 100-hue test. Rod influence was taken as the difference in error scores obtained after complete dark adaptation and during the cone plateau at three mesopic (23, 9, 3 td) and one standard (158 td) light level. On the FM 100, rods produced a differential discrimination loss along a tritan axis as compared with a red–green axis without any bias toward a rod confusion axis. Rods appear to impair discrimination mediated by S-cone pathways, which at moderate levels of illumination can differentially elevate tritan errors on the FM 100.

Prophylactic laser treatment in early age related maculopathy reduced the incidence of exudative complications

AIMTo investigate the effect of prophylactic laser treatment on drusen area and incidence of exudative lesions in patients with soft drusen maculopathy.METHODSIn a prospective study, patients with early age related...

Evaluation of ocular safety

Ninety-six patients with metastatic melanoma treated with two consecutive tirapazamine-cisplatin combination chemotherapy regimens were followed for signs of therapy-related ocular toxicity. Baseline and follow-up data were obtained such that each patient acted as his own control. A battery of vision-related tests was performed. These included: best corrected visual acuity, color vision, retinal fundus examination and electro-oculograms (EOG). A brief health-related quality of vision test was administered at each follow-up visit to detect and evaluate self-perceived changes in visual status. In the first study, 48 patients received i.v. tirapazamine over 2 h at 260 mg/m2 (group 1) while in the second study 48 patients (group 2) received i.v. tirapazamine at 390 mg/m2. Visual system assessment was conducted at three timepoints: first at baseline, then at 6 weeks post-baseline, i.e. after two courses of chemotherapy and visit two upon discontinuation of therapy. There was no difference in visual acuity between group 1 and group 2 at baseline, follow-up 1 or at follow-up 2. Grouped data indicate that visual acuity was not affected by either dosage of chemotherapy. Group 1 at baseline found 15% below the normal EOG cutoff point, increasing to 23% at follow-up 1 and increasing at follow-up visit 2 to 33%. Group 2 demonstrated the same EOG findings, but the results were more magnified: baseline, 24%; follow-up 1, 44%; and follow-up 2, 44%. After eliminating those with abnormal color vision baselines, 21% (nine of 42) group 1 patients demonstrated abnormal color vision total error scores at follow-up 1 and 16.7% (four of 24) at follow-up 2. Few individuals showed changes in the higher dosage group. With the exception of one person in each dosage group, all changes were along the blue-yellow (tritan) axis, which is associated with acquired color defects. Of 96 patients examined, proven fundus changes were found in only four subjects. These fundus findings included retinal hemorrhages, retinal nerve fiber layer infarcts (cotton wool spots) and small retinal pigment epithelium detachments. There was no systematic statistical significant difference among the various measures of visual system outcome between groups or test times. Data from all tests for individual patients in both groups reveals a sporadic distribution of changes in visual system tests. If toxicity were pronounced, one would expect consistency in the findings and all or most of the assessment tests would be abnormal for a particular patient. However, patients who were abnormal on one measure of acuity were not necessarily abnormal on the other measures.

Cone and rod function in cone degenerations

Progressive cone dystrophy (CD) is usually marked in the initial stages by reduced visual acuity, color vision deficiency and alterations in the photopic electroretinogram, while morphological alterations can be very mild; in some forms rods are affected in a later stage as well. We examined 40 patients with progressive cone dystrophy to determine the extent of functional losses in the cone system with psychophysical tests. A great variety of visual acuity and fundus alterations was found. Myopia was present in 74% of the patients. An autosomal dominant pattern of inheritance predominated (32%). No prevalence of gender was found. The age of onset ranged between 10 and 30 yr. All patients had progression of their symptoms. The total error score in color arrangement tests, the saturated Farnsworth Panel D-15 and the Farnsworth-Munsell 100-hue test, was pathologic with a predominance of confusions along the tritan and scotopic axis. Especially if visual acuity was below 0.5, color vision defects increased, but color vision defects were also found in patients with normal visual acuity. A general decrease of sensitivity in all three cone mechanisms was observed in measurements of spectral sensitivity. Moreover, cone-cone interaction as tested by transient tritanopia measurements was usually disturbed. In the dark adaptation function the threshold of the cone branch was usually elevated. These tests provide a good means to ascertain the correct diagnosis in early stages of the disease and to monitor progression in patients suffering from cone dystrophy.

Hepatic Retinopathia. Changes in Retinal Function

In patients suffering from hepatic failure, the brain is subject to defined morphological and functional changes known as hepatic encephalopathia (HE). The morphological changes are dominated by glial cells (Alzheimer-type II astrocytes). It has recently been possible to demonstrate, that the retinal glia (Müller) cells undergo similar morphological changes. The present study was carried out in order to reveal if these Müller cell changes cause any characteristic functional deficits. We examined 11 patients with different stages of HE due to liver cirrhosis. Six patients were at stage 0 or 1 (group I) and five at stage 2 or 3 (group II). They underwent ophthalmological routine examination, colour vision testing and standard ERG recording. None of the patients reported impaired vision, in daylight or at night. There were no fundus abnormalities except very mild changes of the pigment epithelium and abnormal reflexes of the inner limiting membrane, especially in the higher HE stages. The number of confusions in the colour arrangement test increased with the higher stages of HE, preferably in the tritan axis. The scotopic a- and b-waves of the electroretinogram (ERG) were almost unchanged in group I and significantly decreased and delayed in group II. The photopic ERG b-wave amplitudes were changed in a similar fashion. Oscillatory potentials proved to be most sensitive to hepatotoxic changes. Their latencies were significantly delayed even in group I. Amplitudes were decreased significantly only in group II. Patients suffering from hepatic failure and accompanying HE display functional abnormalities of the retina. These are best demonstrated by the ERG, and correlate well with the degree of HE. A hypothesis is presented that relates the observed functional changes to altered neurotransmitter levels and impaired retinal glial-neuronal interaction, due to Müller cell damage caused by elevated ammonia levels. © 1997 Elsevier Science Ltd.

Colour contrast thresholds are normal in functional amblyopia.

We evaluated colour contrast thresholds in patients with unilateral functional amblyopia. A computer-controlled colour vision test was used to determine colour contrast thresholds along a blue-yellow tritan axis. Prior to the threshold measurement, a heterochromatic flicker brightness test was performed to ensure isoluminance between the test stimulus and the background for every subject individually. Luminance contrast thresholds were also measured using the same computer-based system. Twenty amblyopic patients were tested. All showed normal tritan colour contrast thresholds both for their amblyopic eye and non-amblyopic fellow eye. Luminance contrast thresholds were elevated in all 6 refractive amblyopic eyes, in 4 of 9 strabismic eyes and in 2 of 5 mixed amblyopic eyes. Colour contrast thresholds are normal in functional amblyopia (with central fixation). Whenever elevated tritan colour contrast thresholds are found in patients with a decreased visual acuity, other causes of visual impairment are to be evaluated.

Colour contrast sensitivity in patients with soft drusen, an early stage of ARM.

The present institutional study was undertaken in order to determine whether testing of colour contrast sensitivity is valuable in detecting early functional changes in patients at initial stages of age-related maculopathy (ARM). The study included 27 patients with soft drusen as an early sign of ARM and 29 age-matched normals. The area occupied by drusen was determined using a computer program. Colour contrast sensitivity was measured with a computer graphics system. Visual acuity, central visual field (Humphrey Field Analyser) and colour vision (D-15 panel) were normal in both groups. Mean colour contrast sensitivity was significantly lower in patients with early ARM (for the protan axis: p = 0.00019, for the deutan axis: p = 0.000078 and for the tritan axis: p = 0.000096) than in the controls. Interindividual variations were large. There was a tendency towards a bimodal distribution for all three colour axes, most evident for the tritan axis. We found a correlation of the drusen area with the protan and deutan thresholds for the fundus colour photographs r = 0.5 (p < 0.01) and r = 0.4 (p < 0.05), respectively, and with the tritan threshold for the angiograms r = 0.5 (p < 0.05). The findings suggest that colour contrast sensitivity may offer an additional possibility of predicting exudative ARM. Whether the patients with the highest thresholds are those who will be the first to show progression with indications of exudative ARM is not yet known. The patient group will be followed up in order to elucidate this question.