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At least 1,135 records · Page 63Linked to original sources
PubMed1991

Deficiencies in human neonates' color vision: photoreceptoral and neural explanations.

Several photoreceptoral and neural models have been proposed to account for the development of human vision. To further evaluate those applicable to color vision, the present study examined 40 neonates' (mean age = 3.2 days) chromatic-achromatic discriminations in the mid-spectral region by using an habituation procedure and measures to minimize achromatic cues. Results indicated that newborns showed evidence of discriminating broad-band orange (lambda peak = 595 nm) but not yellow-green (lambda peak = 565 nm) lights from achromatic lights of varying luminance. Collectively, these and previous results imply that although newborns have at least dichromatic color vision, they possess relatively poor chromatic-achromatic discrimination in two spectral regions - in the short-wavelengths (including stimuli of 470-480 nm) and in the mid-wavelengths (including 565 nm). Although several hypotheses were considered, newborns' chromatic 'neutral zones' are best accounted for by models proposing that early color vision is limited by a general inefficiency of preneural (photoreceptoral and optical) mechanisms and/or by a selective immaturity of the SWS cones or the B/Y opponent channel.

Arousal↗
PubMed2005

[Long-term effects of iterative diving on visual field, color vision and contrast sensitivity in professional divers].

PURPOSE: To assess long-term functional effects of iterative diving, we studied visual field, color vision, and contrast sensitivity in 21 French Navy professional divers and 21 controls. PATIENTS AND METHODS: This retrospective study investigated a population of 21 divers and 21 controls. All subjects were male. The inclusion criterion for divers was a total number of dives greater or equal to 1,000. Exclusion criteria for the two groups were glaucoma, ocular hypertension, smoking, and vasospastic risks. Additional exclusion criteria for controls were any history of diving practice and of hyperbaric oxygen therapy. The visual field was examined with a Humphrey Central 30-2 threshold test. Moreover, we explored spatial contrast sensitivity using Metrovision Moniteur Ophtalmologique "STAT" program and color vision with desaturated 15 hue test. RESULTS: None of the divers had any loss of spatial contrast sensitivity. There was a high frequency of yellow-blue axis color vision defects (45.2%) in the diver group. Regarding visual field, corrected pattern standard deviation was significantly higher in divers (p<0.01). CONCLUSION: These findings suggest that iterative diving may cause subclinical functional effects on vision. Further studies will be needed to determine the exact setting of this repercussion upon macula and/or the optic nerve.

Adult↗
PubMed2001

Color vision after laser in situ keratomileusis.

PURPOSE: To evaluate the effect of laser in situ keratomileusis (LASIK) on color vision. SETTING: Department of Ophthalmology, China Medical College Hospital, Taichung, Taiwan. METHOD: This prospective study comprised consecutive patients having LASIK. Patients were eligible for inclusion if they had a best corrected visual acuity of 20/20 or better and a normal color vision test preoperatively and an uncorrected near visual acuity of 20/40 or better postoperatively. Color vision was tested using the Farnsworth-Munsell 100-hue test (FM 100 test) preoperatively and 1 day, 1 week, and 1 month postoperatively. RESULTS: Twenty-nine eyes of 15 patients having LASIK were enrolled in the study. The mean patient age was 29.2 years +/- 2.9 (SD). The mean preoperative spherical equivalent refractive error was -5.6 +/- 1.8 diopters, and the mean preoperative error score of the FM 100 test was 3.79 +/- 1.55. After surgery, no significant change in the error score was observed at 1 day (4.30 +/- 1.07, P =.1039, paired t test), 1 week (3.72 +/- 1.25, P =.8125, paired t test), or 1 month (3.97 +/- 1.29, P =.6149, paired t test). CONCLUSION: Laser in situ keratomileusis did not affect color vision evaluated by the FM 100 test.

Adult↗
PubMed1996

Color vision in patients with a silicone intraocular lens.

PURPOSE: To test color vision in eyes with a silicone intraocular lens (IOL) and compare it with that in normal phakic eyes. SETTING: University Eye Clinic of Kuopio, Finland. METHODS: Color vision in 33 patients from 50 to 69 years old with a silicone IOL was evaluated with the Farnsworth-Munsell 100 hue test (FM 100) and the Color Vision Meter 712 (CVM) anomaloscope. In the FM 100 test, 37 normal phakic eyes served as controls; 21 were 50 to 59 years old and 16, 60 to 69 years old. In the CVM, 46 normal phakic eyes served as controls; 21 were 50 to 59 years old and 25, 60 to 69 years old. Nine of the 33 patients had a silicone IOL in one eye and a poly(methyl methacrylate) (PMMA) IOL in the other; the color vision in the two eyes was compared. RESULTS: The FM 100 results showed no significant difference between the silicone IOL and control eyes. In the CVM examination, the blue equation showed a significantly greater shift to the green side (patient sees more blue) in the silicone IOL group than in the control group. Other CVM results were similar between groups. No significant difference was found in any test between the 9 PMMA IOL eyes and the contralateral silicone IOL eyes. CONCLUSION: Eyes with a silicone IOL had color discrimination ability similar to that of normal phakic eyes. In the blue color sensitivity test, the silicone IOL eyes had significantly better results. There were no significant differences between eyes with a silicone IOL and contralateral eyes with a PMMA IOL.

Aged↗
PubMedDate not supplied

Critical issues in the use and analysis of the Lanthony Desaturate Color Vision test.

The Lanthony Desaturate Color Vision test (D-15d) has been used to demonstrate the incidence of acquired color vision defects resulting from toxic exposure. The D-15d is a sensitive test designed to grade color deficiencies, but results can be difficult to interpret beyond the qualitative level, and the high incidence of errors reported for controls in some toxicology studies raises questions about how to effectively use this test. This article reviews standard administration of the test, physical determinants of performance, classification of acquired color vision defects, and methods of analysis that have been used to quantify results. The basis for a new method of analysis is discussed, illustrating the source of some characteristic errors, and recommendations are made for test protocols to attempt to more closely identify the type of color vision loss with the goal of identifying the site of toxicological insult.

Color Perception↗
PubMedDate not supplied

Effects of high doses of toluene on color vision.

High exposure to toluene may cause optic neuropathy and retinopathy, both associated with dyschromatopsia. Another solvent, ethanol, is known to induce acute blue-yellow dyschromatopsia. This study investigated the acute effects of high doses of toluene on color vision. Eight male printshop workers were examined before and after cleaning printing containers with pure toluene. After cleaning, concentrations of toluene in blood were between 3.61 and 7.37 mg/l. Color vision was tested with the Farnsworth panel D-15 test, the Lanthony desaturated panel D-15 test, and the Standard Pseudoisochromatic Plates part 2. For control of possible acute effects, eight workers of a metal-working factory without any neurotoxic exposure were tested according to the same procedure. Acute exposure to toluene did not cause impairment of color vision. However, statistical power is limited due to the small number of exposed subjects. Color vision of the printshop workers tested before cleaning was slightly impaired (statistically not significant) when compared with unexposed subjects.

Adult↗
PubMed1987

Colour vision abnormalities in multiple sclerosis.

A battery of colour vision tests was employed to evaluate visual function in patients with multiple sclerosis (M.S.). Colour deficits were found in 45% of patients tested with the Ishihara plates and 42.5% of patients tested with the FM 100-Hue test. 65% of M.S. patients failed at least one of the tests. The colour vision deficits were not restricted to patients with optic neuritis or with visual evoked potential (VEP) abnormalities and there was no significant correlation between an abnormal VEP latency and a colour vision deficit. Colour vision testing may be a useful option to consider in the investigation of M.S. patients, even if there is no other evidence of visual system involvement.

Adult↗
PubMed1990

Role of the color-opponent and broad-band channels in vision.

The functions of the primate color-opponent and broad-band channels were assessed by examining the visual capacities of rhesus monkeys following selective lesions of parvocellular and magnocellular lateral geniculate nucleus, which respectively relay these two channels to the cortex. Parvocellular lesions impaired color vision, high spatial-frequency form vision, and fine stereopsis. Magnocellular lesions impaired high temporal-frequency flicker and motion perception but produced no deficits in stereopsis. Low spatial-frequency form vision, stereopsis, and brightness perception were unaffected by either lesion. Much as the rods and cones of the retina can be thought of as extending the range of vision in the intensity domain, we propose that the color-opponent channel extends visual capacities in the wavelength and spatial-frequency domains whereas the broad-band channel extends them in the temporal domain.

Animals↗
PubMedDate not supplied

Retinal ganglion cell coding in simulated active vision.

The image on the retina is almost never static. Eye, head, and body movements, and externally generated motion create rapid and continual changes in the retinal image ("active vision"). Virtually all vision in animals such as primates, which make saccades as often as 3-4 times/s, is based on information that must be derived from the first few hundred milliseconds after sudden, global changes in the retinal image. These changes may be accompanied by large changes in area mean luminance, as well as higher order image contrast statistics. This study investigated how retinal ganglion cell responses, whose response properties have been typically studied and defined in a stable stimulus regime, are affected by sudden changes in mean luminance that are characteristic of active vision. Specifically, the steady-state responses of retinal ganglion cells to static or moving square-wave grating stimuli were recorded in an isolated, superfused rabbit eyecup preparation and compared to responses after saccade-like changes in luminance. The manner of coding after luminance changes was different for different ganglion cell classes; both suppression and enhancement of responses to patterns following luminance changes were found. Brisk-transient Off cells unambiguously signaled the darkening of the overall image, but were also modulated by the subsequently appearing grating stimulus. Several types of On-center cell behavior were observed, ranging from strong suppression of the subsequent response by luminance changes, to strong enhancement. Overall, most ganglion cells distinguished static patterns after a luminance change via differences in their spike discharges nearly as well as before, although there were clear asymmetries between the On and Off pathways. Changes in mean luminance in some ganglion cells, such as On-Off directionally selective ganglion cells, could create large phase shifts in the response to patterned, moving stimuli, although these stimuli were still detected immediately after luminance changes. The results of this study show that the image dynamics of active vision may be a fundamental challenge for the visual system because of strong effects on retinal ganglion cell function. However, rapid extraction of unambiguous information after luminance changes appears to be encoded in differences in the spike discharges in different retinal ganglion cell classes. Asymmetries among ganglion cell classes in sensitivity to luminance changes may provide a basis by which some provide the "context" for interpreting the firing of others.

Animals↗
PubMed2003

Animal colour vision--behavioural tests and physiological concepts.

Over a century ago workers such as J. Lubbock and K. von Frisch developed behavioural criteria for establishing that non-human animals see colour. Many animals in most phyla have since then been shown to have colour vision. Colour is used for specific behaviours, such as phototaxis and object recognition, while other behaviours such as motion detection are colour blind. Having established the existence of colour vision, research focussed on the question of how many spectral types of photoreceptors are involved. Recently, data on photoreceptor spectral sensitivities have been combined with behavioural experiments and physiological models to study systematically the next logical question: 'what neural interactions underlie colour vision?' This review gives an overview of the methods used to study animal colour vision, and discusses how quantitative modelling can suggest how photoreceptor signals are combined and compared to allow for the discrimination of biologically relevant stimuli.

Animals↗
PubMed2000

Glider and Vision: two new families of miniature inverted-repeat transposable elements in Xenopus laevis genome.

We have characterised from Xenopus laevis two new short interspersed repetitive elements, we have named Glider and Vision, that belong to the family of miniature inverted-repeat transposable elements (MITEs). Glider was first characterised in an intronic region of the alpha-tropomyosin (alpha-TM) gene and database search has revealed the presence of this element in 10 other Xenopus laevis genes. Glider elements are about 150 bp long and for some of them, their terminal inverted repeats are flanked by potential target-site duplications. Evidence for the mobility of Glider element has been provided by the presence/absence of one element at corresponding location in duplicated alpha-TM genes. Vision element has been identified in the promoter region of the cyclin dependant kinase 2 gene (cdk2) where it is boxed in a Glider element. Vision is 284bp long and is framed by 14-bp terminal inverted repeats that are flanked by 7-bp direct repeats. We have estimated that there are about 20,000 and 300 copies of Glider and Vision respectively scattered throughout the Xenopus laevis genome. Every MITEs elements but two described in our study are found either in 5' or in 3' regulatory regions of genes suggesting a potential role in gene regulation.

Animals↗
PubMed2000

Postattentive vision.

Much research has examined preattentive vision: visual representation prior to the arrival of attention. Most vision research concerns attended visual stimuli; very little research has considered postattentive vision. What is the visual representation of a previously attended object once attention is deployed elsewhere? The authors argue that perceptual effects of attention vanish once attention is redeployed. Experiments 1-6 were visual search studies. In standard search, participants looked for a target item among distractor items. On each trial, a new search display was presented. These tasks were compared to repeated search tasks in which the search display was not changed. On successive trials, participants searched the same display for new targets. Results showed that if search was inefficient when participants searched a display the first time, it was inefficient when the same, unchanging display was searched the second, fifth, or 350th time. Experiments 7 and 8 made a similar point with a curve tracing paradigm. The results have implications for an understanding of scene perception, change detection, and the relationship of vision to memory.

Attention↗
PubMed2004

Panoramic search: the interaction of memory and vision in search through a familiar scene.

How do observers search through familiar scenes? A novel panoramic search method is used to study the interaction of memory and vision in natural search behavior. In panoramic search, observers see part of an unchanging scene larger than their current field of view. A target object can be visible, present in the display but hidden from view, or absent. Visual search efficiency does not change after hundreds of trials through an unchanging scene (Experiment 1). Memory search, in contrast, begins inefficiently but becomes efficient with practice. Given a choice between vision and memory, observers choose vision (Experiments 2 and 3). However, if forced to use their memory on some trials, they learn to use memory on all trials, even when reliable visual information remains available (Experiment 4). The results suggest that observers make a pragmatic choice between vision and memory, with a strong bias toward visual search even for memorized stimuli.

Exploratory Behavior↗
PubMed1996

Radiotherapy treatment of age-related subfoveal neovascular membranes in patients with good vision.

This prospective study investigated whether low-dose ionising radiotherapy preserved vision and caused membrane regression in patients with age-related subfoveal neovascular membranes (SFNVMs) or vascularised pigment epithelial detachments (PEDs) and relatively good initial visual acuities. Twenty-five patients with initial Snellen acuities of 6/24 or better were treated with low-dose external beam radiotherapy. Of the patients with SFNVMs, visual acuities were maintained or improved in 58% at 6 months and 53% at 1 year. Neovascular membrane size was assessed by image analysis and showed some regression in 47% and 41% at 6 and 12 months respectively. These results suggest that patients with SFNVMs and good vision may benefit from radiotherapy, faring better than previous reports of the natural history of this condition. Conversely, patients with vascularised PEDs did not appear to benefit from radiotherapy. Only 17% maintained their vision at 1 year and 33% suffered retinal pigment epithelial tears. The results from patients with SFNVMs and good initial vision, excluding those with vascularised PEDs, are encouraging however, any benefit from this treatment needs to be proven by controlled trials with long follow-up.

Aged↗
PubMed2001

Detection of animals in natural images using far peripheral vision.

It is generally believed that the acuity of the peripheral visual field is too poor to allow accurate object recognition and, that to be identified, most objects need to be brought into foveal vision by using saccadic eye movements. However, most measures of form vision in the periphery have been done at eccentricities below 10 degrees and have used relatively artificial stimuli such as letters, digits and compound Gabor patterns. Little is known about how such data would apply in the case of more naturalistic stimuli. Here humans were required to categorize briefly flashed (28 ms) unmasked photographs of natural scenes (39 degrees high, and 26 degrees across) on the basis of whether or not they contained an animal. The photographs appeared randomly in nine locations across virtually the entire extent of the horizontal visual field. Accuracy was 93.3% for central vision and decreased almost linearly with increasing eccentricity (89.8% at 13 degrees, 76.1% at 44.5 degrees and 71.2% at 57.5 degrees ). Even at the most extreme eccentricity, where the images were centred at 70.5 degrees, subjects scored 60.5% correct. No evidence was found for hemispheric specialization. This level of performance was achieved despite the fact that the position of the image was unpredictable, ruling out the use of precued attention to target locations. The results demonstrate that even high-level visual tasks involving object vision can be performed using the relatively coarse information provided by the peripheral retina.

Adult↗
PubMed1992

Routine ultrasonography in utero and subsequent vision and hearing at primary school age.

The study was performed to investigate any associations between routine ultrasonography during pregnancy and subsequent reduced vision and/or hearing among children. A follow-up was carried out of primary school children born to women who took part in two randomized, controlled trials of routine ultrasonography during pregnancy. Of 2428 eligible singletons, 2161 (89%) were followed up with a parental questionnaire and with information from maternal and child health centers. Parents assessed vision and hearing in their children and reported their observations in questionnaires. At the age of 7 years, the children were also screened with bilateral visual acuity tests and pure tone audiometry at public maternal and child health centers. No significant differences between ultrasound-screened children and their controls were found in the parental assessment of vision or hearing. The objective tests did not show any significant differences between children in the two groups with regard to visual acuity or hearing. The risk of reduced vision or hearing was no greater for children of mothers who had been offered routine ultrasonography during pregnancy than for those whose mothers had not received that offer.

Journal Article↗
PubMed1987

Perception of positional relationships between line segments in eccentric vision.

The encoding of positional relationships between pattern elements in eccentric vision was studied with different patterns consisting of the same short line segments in different positions. In each trial two stimulus patterns were flashed one above the other and the subject had to decide whether the patterns were identical or mirror symmetric (experiment 1) or whether the patterns were the same or different (experiments 2 and 3). The ability to discriminate between identical and mirror symmetric patterns was reduced in eccentric vision, even when the patterns were size-scaled according to the cortical magnification factor and thus the patterns were similarly visible at the different eccentricities. The results agree with the notion that eccentric vision is inferior to central vision in tasks which require proper encoding of information about the relative positions of pattern elements.

Attention↗
PubMed1997

Induced pupillary hippus following near vision: increased occurrence in visual display unit workers.

Using a quasistatic method, it has been found previously that one-third of normal subjects retained pupillary constriction under empty-field conditions for a substantial period following a near-vision task. This pupil after-effect was dissociated from adaptation of tonic accommodation. In this paper, essentially the same method was used to investigate further the effects of near vision on pupil response in VDU (Visual Display Unit) workers with complaint of general fatigue and/or asthenopia. In some cases, large and slow pupillary oscillation accompanied by miosis was noted after near vision. Pupillary oscillation is a well-established phenomenon that has a broadly spread frequency spectrum with an occasional component 'hippus' at approximately 0.2 Hz. A proportion of subjects (30 out of 100) showed hippus, a consistent oscillation of 0.22 Hz (SD = 0.03 Hz) in VDU workers, while only one out of 24 normal subjects showed this. Occurrence of pupillary hippus following near vision increased in VDU workers. It was suggested that this hippus is concerned with cumulative asthenopia and/or general fatigue although the origin of hippus is still unknown.

Accommodation, Ocular↗