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More than half of the cases with complaints of chromatopsia had recent-onset retinal pathology. Erythropsia due to bright (sun-)light is a relatively common finding in aphakia and pseudophakia. UV-coated intraocular lenses do not provide complete protection. Cerebrovascular chromatopsia usually occurs in transient attacks.
Acquired color deficiencies may correspond to a general, non-selective loss of visual sensitivity. We summarise evidence for the opposite view that, in some cases, chromatic sensitivity can be more (or less) reduced than achromatic sensitivity. This evidence is based on: (1) Disproportion between chromatic and achromatic isopters; (2) Differential damage to red-green and blue-yellow color vision; (3) Detection static perimetry; (4) The foveal photochromatic interval; (5) The two color threshold technique; (6) Spectral sensitivity on a white background; (7) Single unit and histological studies of the retina and lateral geniculate nucleus; (8) Lesions of the prestriate color area; (9) Selective damage to achromatic processes. Possible problems of interpretation are considered and a new technique for comparing chromatic and achromatic sensitivity is briefly described.
In congenital total color blindness direct current recordings of the electroretinogram displayed a negativity following the b-wave, not present in recordings of normal eyes. This negativity, preceding the onset of the c-wave, is probably caused by the lack of cone contribution to the positive c-wave component.
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Forty-eight diabetic patients (82 eyes) were examined with four different colour vision tests and one blood glucose strip-test. The ages of the patients varied from 23 to 65 years (mean 44.3 years +/- 11.4, SD), the duration of diabetes from 13 to 41 years (mean 25.8 +/- 6.2), and the visual acuities from 0.2 to 1.0 (mean 0.8 +/- 0.2). Of the eyes, 77 had had photocoagulation, 25 had small peripheral lens opacities, and 55 had slight background retinopathy. The colour vision tests were: the Standard Pseudoisochromatic Plates part 2 (SPP2), the Lanthony Tritan Album, the Farnsworth Panel D 15 test and the box III of the Farnsworth-Munsell 100 hue (FM 100) test. The blood glucose test was Haemo-Glukotest 1-44. Of the 82 eyes, 38 incorrectly saw Haemo-Glukotest strips. The SPP2 test found 89% of the eyes, the Tritan Album 55%, the Panel D 15 71%, and the box III of the FM 100 test 76%. The strips were correctly interpreted in 44 of the eyes. However, 36% of them failed the SPP2, 16% the Tritan Album, 11% the Panel D 15 test and 18% the box III of the FM 100 test. The Panel D 15 test and the box III of the FM 100 test would be useful in screening those diabetics who cannot correctly interpret the colour-dependent glucose test-strips and would need a blood sugar meter for their blood glucose level testing.
The cone dystrophies can be subdivided into 3 functional stages: central cone disease, peripheral cone disease and diffuse cone disease, respectively. In the patient material of our clinic the sex distribution of patients presenting with te diffuse cone disease stage was abnormal: 22 males and 3 females. The authors suggest that the diagnosis X-linked cone dystrophy often is overlooked.
The spectral response curve (amplitude versus wavelength) of the R2 of the early receptor potential (ERP) was studied in normal, protan, and deutan subjects. The R2 amplitude peaked at 520 nm in most normal subjects. The R2 at long wavelengths was smaller than normal in protans and larger than normal in deutans when the maximum amplitudes were normalized to 100% at the peak. The ratio of the R2 amplitude at 460 nm to that at 600 nm clearly differed between protans and deutans. The ERP and the rapid off-response, which is mainly due to the cessation of the late receptor potential, were recorded in the same subjects. The ratio of the sensitivity of the rapid off-response at 500 nm to that at 600 nm was correlated with the ratio of the R2 amplitude at 460 nm to that at 600 nm (correlation coefficient, 0.823, p less than 0.001). This study, in conjunction with our previous study, indicates that the abnormality is in the outer segments of the cones in protans and deutans.
The spectral sensitivity of the rapid off-response in the electroretinogram is found to be abnormal in all protans and deutans so far tested, and in some of their genetic carriers. The rapid off-response is an objective means of assessing the x-linked recessive color deficiencies and their carrier state.
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Electroretinograms to white and color stimuli were recorded in four normal subjects and nine subjects with different cone dysfunctions, including protanopia, cone dystrophy, cone dystrophy with supernormal b-waves at dark adaptation, cone dystrophy with missing b-waves during light adaptation and rod-cone dystrophy with blue cone hypersensitivity. Color stimuli were obtained with Kodak Wratten filters in blue, blue-green, green, yellow and red. Electroretinograms to all stimuli were recorded during dark and light adaptation with different stimulus intensities and to 30-Hz flicker stimulation. In protanopia, responses to red during light adaptation and flicker stimulation were reduced. All cone dystrophies showed reduced amplitudes and prolonged implicit times to red when dark adapted. The light-adapted responses were equally reduced to all color stimuli in cone dystrophy and cone dystrophy with supernormal b-waves. Contrary to other cone dystrophies, in cone dystrophy with missing b-waves, responses to red were severely reduced and responses to green were preserved, indicating a predominantly red cone dysfunction. Blue cone hypersensitivity was clearly distinct from other dystrophies in having large response to blue and blue-green and much smaller responses to all other colors in all stimulus conditions. The electroretinogram with color stimuli allowed separation of different cone dysfunctions and identification of new retinal dysfunction syndromes.
The spectral sensitivity of the rapid off-response in the electroretinogram was studied in monozygotic female twins. One case was diagnosed as congenital deuteranomaly, and the other was normal. The log ratio of the sensitivity at 480 nm to the sensitivity at 620 nm (log S480/S620) was within the deutan range in the first case and within the normal range in the second. The two case were determined to be different at the retinal receptor level by study of the rapid off-response. This result of the rapid off-response was consistent with the results of the psychophysical examinations.
Color vision testing was performed on a group of ten black tyrosinase-positive albino patients and a group of normal subjects. Testing was accomplished by means of a Farnsworth-Munsell (F-M) 100-hue test and Nagel anomaloscope. As a group, the albino patients showed an increase in number of errors scored on the FM-100 hue test, without any specific axis in the majority of cases. Results on the Nagel anomaloscope showed a 'widening' into the red end of the Rayleigh equation. A possible explanation for this apparent widening is discussed, which emphasizes anticipated results of matching ranges obtained on extrafoveal cones.
BACKGROUND: Vitamin A deficiency with eye symptoms has been reported in patients with cystic fibrosis who received the recommended daily intake of vitamin A. METHODS: We measured serum retinol, dark adaptation, contrast sensitivity, and dry eye status in 35 adult cystic fibrosis patients to ascertain whether they had ocular signs or symptoms. RESULTS: Median serum retinol concentration was 1.95 mumol/l, range 1.08-4.01 mumol/l, with no values indicating vitamin A deficiency. Retinal light sensitivity was normal. Nineteen patients had reduced contrast sensitivity. Conjunctival imprints all showed plenty of goblet cells, but were characteristic of dry eye in 42% of patients (n = 14). Decreased tear film stability was found in 49% (n = 17), tear production was low in 31% (n = 11), and 23% (n = 8) showed an increased amount of dying epithelial cells. Nine patients (26%) had keratoconjunctivitis sicca according to the Copenhagen criteria. CONCLUSION: Our patients had no biochemical or clinical signs of vitamin A deficiency. We speculate that the high incidence of dry eye could be a primary manifestation of cystic fibrosis.
The term scotopization refers to the intrusion of rod activity in colour vision when assessed under photopic observation conditions. Scotopization is an important symptom of cone dystrophies. The detection of scotopization is not easy. With the Nagel-II anomaloscope scotopization can be detected in two ways. One method is new and this method is described in the present paper.
The Desaturated Panel D-15 is analogous in design to the standard Panel D-15 but of lower purity (chroma 2 Munsell); the test is more sensitive to mild and moderate losses in chromatic discrimination ability. Combination of the results of both tests allows recognition of several degrees of chromatic discrimination loss.
The New Color Test allows estimation of the neutral zone (separation phase) and the characteristic color confusions (classification phase) using Munsell colors. The width of the neutral zone is estimated by the ranges of hues confused with grey. The severity of chromatic discrimination loss for a given axis is estimated by the range of chromas confused with grey.
The diagnosis of patients with rod monochromatism (RM) and blue-cone monochromatism (BCM) may be difficult. The relative direction and symmetry of nystagmus of the two eyes, as well as the existence or nature of rhythmic head movements, are not known. We analyzed simultaneous eye and head movement recordings of 16 patients with RM and three patients with BCM. Longitudinal examinations were performed in seven patients. Younger patients had pendular, intermittent or continuous oblique nystagmus with both eyes oscillating in phase or out of phase with equal amplitudes. Older patients had continuous symmetrical oblique jerk nystagmus with decreasing velocities in the slow phase. In two children, we demonstrated evolution from pendular to predominantly jerk nystagmus. Rhythmic head movements were detected in all children. Patients with RM and BCM exhibit a distinct entity of nystagmus and can be differentiated from patients with congenital or latent nystagmus. However, eye and head movements can mimic spasmus nutans.
New clinical methods are proposed to assess (1) neuronal activities of the retinal inner layers including amacrine cells by means of the oscillatory potential, (2) photopic function through the rapid decay in the off-response and (3) activities of the retinal pigment epithelium through susceptibility of the standing potential of the eye to osmotic stress and to Diamox. These new methods are able to reveal otherwise undetectable retinal disorders.