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At least 1,279 records · Page 71Linked to original sources
PubMed2000

Perceptual deficits after lesions of inferotemporal cortex in macaques.

This study used a novel approach to examine a much studied question, the nature of visual deficits caused by lesions of the inferotemporal cortex (IT). Unlike many previous studies of IT lesions, we de-emphasized early, non-specific disruptions of testing caused by the lesions, and instead concentrated on permanent changes in thresholds. This approach produced unexpected results that suggest a re-evaluation of the traditional view of the role of the IT cortex in shape perception and such related visual abilities as perceptual invariances, visual grouping, the visibility of illusory contours and the performance of oddity discriminations. In addition, the measurement of stable, post-lesion hue discrimination thresholds gave us a different perspective on the severity of color vision deficits which result from lesions of the IT cortex. We found that shape distortion thresholds were not permanently elevated by IT lesions and, indeed, showed no greater transitory disruption than did other visual abilities. This result is inconsistent with the common view that IT is critical to shape discriminations. Two other visual abilities that would be expected to be disrupted by IT lesions - the visual grouping of misoriented line segments and shape invariances (failure of irrelevant stimulus changes to disrupt shape distortion thresholds) - were not affected by IT lesions. However, shape discriminations based on illusory contours and some oddity discriminations were severely and permanently affected. Our results also showed that IT lesions caused permanent, moderate to large impairments of color vision, but not color blindness. Bilateral damage to area TEO caused no disruption of performance on any of the abovediscriminations. Our results suggest that the IT cortex in macaques may be critical to the visibility of illusory contours and the performance of some oddity discriminations, that it plays some role in color perception, but that it is not essential for shape, grouping discriminations or perceptual shape invariances.

Animals↗
PubMed1997

The visual photopigments of simple deuteranomalous trichromats inferred from color matching.

Deuteranomalous trichromacy is the most common form of inherited color-vision deficiency. A modern description of its cause is a single abnormality: the normal middle-wave cone photopigment (M) is replaced by a shifted middle-wave pigment (M) that is shared by all deuteranomalous trichromats. This explanation, however, fails to account for the individual differences in color vision observed even within the sub-group of deuteranomals with good chromatic discrimination. An ensemble of color matches is used here to test whether these individual differences reflect differences in the wavelength of peak sensitivity (lambda max) of individual deuteranomals' cone photopigments. The results show variation in both the lambda max and the effective optical density of their cone pigments. The individual differences found in lambda max are in accord with recent molecular biological research that shows individual differences in the genes thought to encode deuteranomalous photopigments.

Adult↗
PubMed1997

Adaptive and maladaptive utilization of color cues by patients with mild to moderate Alzheimer's disease.

The ability to utilize color information was investigated in 12 patients with mild to moderate probable Alzheimer's Disease (DAT) and in 12 age- and gender-matched control subjects. All subjects underwent testing of visual acuity and color vision before being tested with a cognitive task consisting of four conditions (no color, color as attention enhancer, color as valid cue, color as distracter). Although the groups did not differ in visual acuity or color vision, patients with DAT were less accurate than controls in all four conditions of the cognitive task. Both groups performed best with color as a valid cue and worst with color as distracter, but condition had a significantly stronger effect on patients than on controls. It is concluded that color is a potent stimulus attribute for patients with DAT.

Journal Article↗
PubMed2003

Diurnality and cone photopigment polymorphism in strepsirrhines: examination of linkage in Lemur catta.

Trichromatic color vision is routine among catarrhine primates, but occurs only as a variant form of color vision in some individuals in most platyrrhine genera. This arises from a fundamental difference in the organization of X-chromosome cone opsin genes in these two lineages: catarrhines have two opsin genes specifying middle- and long-wavelength-sensitive cone pigments, while platyrrhines have only a single gene. Some female platyrrhine monkeys achieve trichromacy because of a species polymorphism that allows the possibility of different opsin gene alleles on the two X-chromosomes. Recently, a similar opsin gene polymorphism was detected in some diurnal strepsirrhines, while at the same time appearing to be absent in any nocturnal genera. The aim of this study was to assess whether cone pigment polymorphism is inevitably linked to diurnality in strepsirrhines. Cone photopigments were measured in a species usually classified as diurnal, the ring-tailed lemur (Lemur catta), using electroretinogram flicker photometry, a noninvasive electrophysiological procedure. Each of 12 animals studied was found to have the same middle-wavelength cone pigment, with peak sensitivity at about 547 nm. In conjunction with earlier results, this implies that cone pigment polymorphism is unlikely to exist in this species and that, accordingly, such variation is not a consistently predictable feature of vision in diurnal strepsirrhines.

Animals↗
PubMed1982

Chromatic and luminosity processing in retinal disease.

Color vision loss can be an early sign of eye disease; in many retinal disorders the loss precedes any change in visual acuity. Noninvasive psychophysical methods allow factoring out of preretinal, receptoral, and postreceptoral (neural) components of the color vision change. A loss of chromatic but not achromatic sensitivity occurs for diabetics; the loss is selective for pathways subserving blue-sensitive photoreceptors. Both chromatic and achromatic pathways are altered in glaucoma and senile macular degeneration; the most marked change in central serous choroidopathy is loss of sensitivity somewhere in the blue-sensitive cone pathway. There is evidence that the pathways subserved by blue-sensitive cones have anatomically and physiologically different properties from those served by other receptor types, and they appear particularly vulnerable to disturbances of retinal integrity.

Adult↗
PubMed1993

Fellow eye abnormalities in acute unilateral optic neuritis. Experience of the optic neuritis treatment trial.

BACKGROUND: Visual function in the fellow eye at the onset of unilateral optic neuritis has not been systematically evaluated. The authors prospectively determined the prevalence of abnormalities in the fellow eyes of the 448 eligible patients entered into the Optic Neuritis Treatment Trial. METHODS: All patients underwent testing of visual acuity, contrast sensitivity, color vision, and visual field, as well as magnetic resonance imaging (MRI) of the brain and a neurologic examination. RESULTS: Abnormalities in the fellow eye were found on measurement of visual acuity in 13.8%, contrast sensitivity in 15.4%, color vision in 21.7%, and visual field in 48.0% of patients. The majority of the fellow eye deficits resolved over several months. A higher prevalence of MRI changes consistent with demyelination of the brain was found in patients with a past history of optic neuritis in the fellow eye compared with patients without such a history (P = 0.004). Patients with abnormal fellow eyes but no history of previous optic neuritis were no more likely to have clinical (P = 0.658) or MRI evidence (P = 0.166) of multiple sclerosis than patients with normal fellow eyes. CONCLUSIONS: The improvement of many of the visual deficits indicates that visual abnormalities detected in the fellow eye at the onset of symptomatically unilateral optic neuritis may not represent preexisting optic nerve demyelination. Whether the presence of these deficits is predictive of the development of clinical multiple sclerosis cannot be determined at this time.

Acute Disease↗
PubMed2005

Health- and vision-related quality of life among patients with ocular histoplasmosis or idiopathic choroidal neovascularization at enrollment in a randomized trial of submacular surgery: Submacular Surgery Trials Report No. 5.

OBJECTIVES: To (1) summarize vision-targeted and general health-related quality-of-life scores at baseline and quantify the effect of the ophthalmic problem, (2) evaluate the strength of relations between visual acuity and interview scores, and (3) compare scores for patients who also had choroidal neovascular lesions in the fellow eye (bilateral cases) with those of patients who had choroidal neovascularization in only the study eye (unilateral cases) at time of enrollment in a randomized trial of surgical removal of subfoveal choroidal neovascularization, either associated with the ocular histoplasmosis syndrome or of idiopathic origin. DESIGN: Eligible patients had subfoveal choroidal neovascularization (including some classic choroidal neovascularization) and a visual acuity of 20/50 to 20/800 (Snellen equivalent), inclusive, in the eye to be assigned randomly to surgery or observation. Interviews that incorporated the 39-item version of the National Eye Institute Visual Function Questionnaire (NEI-VFQ) and 2 other instruments were conducted by telephone by trained interviewers before patients enrolled and were assigned randomly to surgery or observation. Information from baseline clinical examinations and fluorescein angiograms interpreted centrally by masked readers was used to classify patients as unilateral or bilateral cases and to provide potential explanations for variability of interview responses using linear regression models. RESULTS: The median overall NEI-VFQ score was 75 (interquartile range, 60-84). The median scores on individual subscales ranged from 55 (general vision) to 100 (color vision). The visual acuity of the better-seeing eye accounted for much of the variability in scores on most NEI-VFQ subscales; a 3-line difference in visual acuity was associated with a 10-point or greater difference in scores on 5 subscales after adjustment for other characteristics of patients and eyes. Scores on most scales of all 3 instruments differed between unilateral cases (n = 167) and bilateral cases (n = 58). Even after adjustment for visual acuity and reading speed of the better-seeing eye, age, gender, and scores on the other instruments, scores on the NEI-VFQ near and distance activities subscales differed by almost 13 and 10 points, respectively, between unilateral and bilateral cases. Neither age nor gender was an important independent explanatory variable for NEI-VFQ scores. CONCLUSIONS: Unilateral and bilateral cases had vision-targeted health-related quality-of-life scores worse than those published for a reference population without eye disease. Furthermore, despite younger age, better visual acuity, and better short-term visual prognosis, bilateral cases had NEI-VFQ scores at baseline similar to those published for 2 groups of patients with age-related macular degeneration. Unidentified factors, in addition to the visual acuity of the better-seeing eye, affected patients' perceptions of visual function.

Adolescent↗
PubMed2007

In vivo fluorescein staining of SI-30NB silicone intraocular lens.

We report a case of a 48-year-old pseudophakic woman who presented 3 weeks after Heidelberg retinal angiography using intravenous sodium fluorescein 2%. Bilateral retinal vasculitis with severe retinal ischemia and extensive capillary dropouts had been diagnosed. Anterior segment examination revealed green staining on the silicone optic of the 3-piece SI-30NB intraocular lens (IOL) (AMO), with no cell or flare in the aqueous humor. The anterior and posterior capsules were not stained. The patient did not report dark vision, double vision, or altered color vision. The anterior and posterior IOL surfaces demonstrated an autofluorescence at the time of fundus photography, which persisted to the 6-week examination although there were no symptoms. This is suggestive of deposits of sodium fluorescein on the IOL surface following angiography.

Female↗
PubMed1993

Photoreceptor twist: a solution to the false-color problem.

In bees and many other insects the majority of photoreceptors are twisted like a corkscrew. Here we show that this structural feature of insect eyes-whose very existence was a source of dispute for several years-is necessary for reliable encoding of information about color. Light reflected from waxy plant surfaces is partially linearly polarized. Moreover, insect photoreceptor membranes are dichroic and thus sensitive to the polarized glare originating from plant surfaces. Taken together, these two phenomena create a serious false-color problem: in the bee's trichromatic color vision system, the color values of a particular part of a plant could be affected not only by the spectral but also by the polarization properties of the reflecting surface. As demonstrated by spectroscopic measurements and optical analyses, the hue of color of a given surface of a plant would change dramatically with the direction of illumination and the bee's line of sight, if the bee possessed straight and thus highly "polarization-sensitive" photoreceptors. However, this false-color problem is overcome completely in photoreceptors that are twisted by exactly the amount we have found to occur in the worker-bee's eye.

Journal Article↗
PubMed2006

Visual field defects and vision-specific health-related quality of life in African Americans and whites with glaucoma.

PURPOSE: To examine the relationship of visual field impairment to vision-specific health-related quality of life and symptoms in a large cohort (N=345) of African Americans and Whites of non-Hispanic origin diagnosed with glaucoma. MATERIALS AND METHODS: Participants consisted of persons > or =55 years of age recruited from university-affiliated ophthalmology and optometry practices in Birmingham, AL who had been diagnosed with glaucoma. Medical records were abstracted to collect information on demographics, visual acuity, and visual fields. A telephone survey was conducted to obtain information on vision-specific health-related quality of life [National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25)], glaucoma symptoms [Glaucoma Symptom Scale (GSS)], and cognitive status (Short Portable Mental Status Questionnaire). Visual fields were used to compute a visual field defect score for each eye based on the Advanced Glaucoma Intervention Study (AGIS) scoring system. RESULTS: Mean NEI VFQ-25 subscale scores ranged from the 50s to 80s. Scores for African Americans and Whites did not differ except for the general health and ocular pain subscales for which African Americans had slightly higher scores. For both African Americans and Whites, as the AGIS score became worse in the better and/or worse eye, there was a decrease in VFQ subscale score for most VFQ subscales including general vision, distance vision, near vision, social functioning, color vision, and peripheral vision (P<0.05). AGIS scores were unrelated to the GSS subscales in African Americans; for Whites, the visual but not the nonvisual subscale was related to AGIS score. CONCLUSIONS: Scores on most subscales of the NEI VFQ-25 and the 2 subscales of the GSS are highly similar in African Americans and Whites of non-Hispanic origin who have been diagnosed with glaucoma. In addition, for both African Americans and Whites, the VFQ subscales for the most part demonstrated good construct validity with respect to the extent of visual field impairment. Results imply that the NEI VFQ-25 and the GSS are appropriate instruments for studying the personal burden of glaucoma in studies whose samples involve both African American and White adults.

Black or African American↗
PubMed2006

Visual outcome after intravenous dexamethasone therapy for idiopathic optic neuritis in an Indian population: a clinical case series.

PURPOSE: To evaluate the clinical profile, response to dexamethasone treatment and visual function outcome in Indian patients with acute optic neuritis. MATERIALS AND METHODS: We conducted an observational study of patients with acute optic neuritis who were treated with intravenous dexamethasone (100 mg in 250 ml of 5% dextrose over 1-2 hours daily, for three consecutive days) and had completed at least two years of follow-up. Parameters assessed included visual acuity, contrast sensitivity, color vision, visual fields, relative afferent pupillary defect (RAPD) and visually evoked potentials. Out of 40 patients studied, 26 patients (33 eyes) had all visual function parameters assessed. Twenty three patients (28 eyes) had completed two years of follow-up and were included for statistical analysis. RESULTS: Improvement in visual acuity was statistically significant for distance after 24 hours of the first dose (P = < 0.001) and for near vision after 24 hours of the second dose (P = 0.006); improvement in color and contrast sensitivity was statistically significant 24 hours after the third dose (P = < 0.001 for color vision and P = 0.013 for contrast sensitivity). Significant improvement in RAPD and visual fields were seen by 1 month (P = 0.005). Recurrence was seen in 4 eyes of 4 patients. No serious side effects were observed. At two years, 82.14% (23 out of 28) eyes had visual acuity > 20/40. CONCLUSION: Treatment with intravenous pulsed dexamethasone led to rapid recovery of vision in acute optic neuritis, without any serious side effects.

Adolescent↗
PubMed1982

The prevalence of visual deficiencies among 1979 general aviation accident airmen.

Analyses of the accident experience of pilots who were monocular, did not meet vision standards, had color vision defects and no operational restrictions, or wore contact lenses have shown higher-than-expected accident experience in previous studies. However, no causal role had been assigned. In the present study of accidents during 1979, the pilots with aphakia and artificial lens implants and the total eye pathology population had significantly higher accident rates, but the monocular pilots did not. Again, no causal role had been ascribe. There are still unresolved questions about the consistent operational performance of monocular pilots, those who are not fully corrected to 20/20 distant visual acuity bilaterally, airmen with near vision deficiencies only who are not required to wear corrective glasses, those without fusion, and several with appreciable pathology who have 20/20 corrected central visual acuity, but about whom we know very little concerning their dynamic, peripheral, depth, or accommodative function.

Accidents, Aviation↗
PubMedDate not supplied

Optic disc pallor: a false localizing sign.

A 20-year-old pregnant woman was referred with bilateral mild visual acuity loss and optic disc pallor. Because of profound color vision deficits out of proportion to her acuity loss, an abnormality of the cone photoreceptors was suspected. An electroretinogram confirmed the diagnosis of a cone dystrophy and precluded further costly and invasive testing. Cone dystrophy should be considered in the differential diagnosis of any patient with bilateral, nonrefractive visual loss, especially if color vision is disproportionately affected, even with a normal retinal appearance and no significant family history.

Adult↗
PubMed1991

Induced color blindness in goldfish: a behavioral and electrophysiological study.

To answer the question whether, like man, ethambutol treated fish would become color-blind, wavelength discrimination was measured behaviorally in goldfish, preceding, during and after ethambutol treatment. The results are that of the three high discrimination abilities at around 400, 500 and 600 nm, ethambutol affected the latter one. Red-green discrimination is lost reversibly leaving the discriminations in the blue-green and violet range unaffected. This red-green discrimination deficiency cannot be accounted for by a loss of long wavelength cones since the ERG and luminosity functions remain unaffected. Intracellular horizontal cell recordings in goldfish show that ethambutol hyperpolarizes all three types of cone driven horizontal cells and changes their color coding such that their spectral characteristics become cone-like as is the case in dark adapted retina. So, the initial effect induced by ethambutol seems to be an adaptation deficiency in color vision related tasks. Human wavelength discrimination and increment threshold spectral sensitivity functions obtained at low luminance levels are compared to behavioral functions in ethambutol treated goldfish. The high similarity between the ethambutol effects in man and goldfish, and the effects observed in the horizontal cell responses in goldfish are highly indicative that horizontal cells play a key role in color vision. So far their function has been puzzling.

Animals↗
PubMed2002

Progress of visual dysfunction in Parkinson's disease.

Studies on progression of Parkinson's disease (PD) mainly focus on the nigrostriatal dopaminergic decline, but not on the visual system. We determined progression of (i) disturbed color vision, assessed with the Farnsworth-Munsell 100 Hue test (FMT) and (ii) intensity of PD in 18 patients. Significant differences occurred between (i) initial FMT error scores and follow-up results 3 years later (P=0.002) and analogously (ii) scored intensity of PD (P=0.002). A relation between computed differences of FMT error scores and rated activities of daily living appeared. Deterioration of color vision progresses in PD.

Color Perception↗
PubMed1988

[Disorders of color perception in subtoxic and toxic digoxin and serum digoxin concentrations].

Using the Farnsworth-Munsell 100-hue test, investigations were carried out in 14 patients with subtoxic to toxic serum concentrations of digoxin (greater than 2.0 ng/ml) and 13 patients with subtoxic to toxic serum concentrations of digitoxin (greater than 30 ng/ml), in order to detect color vision deficiencies related to serum levels of digitalis. As compared to the control group (n = 24) the total error scores were significantly increased for both glycosides and all serum level ranges. No evidence was found indicating that digoxin and digitoxin influence color vision differently. The FM 100-hue test indicated definite improvements in the digoxin group within one day of discontinuing the glycosides, while the digitoxin group only started to normalize a week later. The results are discussed, taking the different pharmacokinetics of the two digitalis glycosides into account.

Aged↗
PubMed2001

Leber hereditary optic neuropathy associated with antiretroviral therapy for human immunodeficiency virus infection.

PURPOSE: Antiretroviral therapy has reduced the morbidity and mortality associated with human immunodeficiency virus (HIV) infection. However, side effects are increasingly recognized, including a commonly reported toxic mitochondrial myopathy. We report such a case of Leber hereditary optic neuropathy in a patient with antiretroviral therapy for HIV infection and speculate on a possible toxic etiologic role in the development of Leber hereditary optic neuropathy by a shared mitochondrial mechanism. METHODS: Case Report. Bilateral optic disk abnormalities observed in a 38-year-old HIV positive man with a family history of Leber hereditary optic neuropathy were documented with fundus photography, color vision testing, and visual field testing. Mitochondrial DNA testing was used to confirm the genetic predisposition to Leber hereditary optic neuropathy. RESULTS: Progressive bilateral optic nerve pallor temporally associated with the administration of antiretroviral medication was observed. Diagnostic testing revealed progressive visual field and color vision loss as well as a mitochondrial DNA mutation consistent with Leber hereditary optic neuropathy. CONCLUSION: Antiretroviral therapy may be associated with the onset of Leber hereditary optic neuropathy in genetically predisposed patients.

Adult↗