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Results for “Visual function”

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At least 1,711 records · Page 95Linked to original sources

PubMed1998

Long-term tamoxifen citrate use and potential ocular toxicity.

PURPOSE: To estimate the prevalence of abnormalities in visual function and ocular structures associated with the long-term use of tamoxifen citrate. METHODS: A single-masked, cross-sectional study involving multiple community and institutional ophthalmologic departments was conducted with a volunteer sample of 303 women with breast cancer currently taking part in a randomized clinical trial to determine the efficacy of tamoxifen (20 mg/day) in preventing recurrences. Participants included women who had never been on drug (n=85); women who had taken tamoxifen for an average of 4.8 years, then been off the drug for an average of 2.7 years (n=140); and women who had been on tamoxifen continuously for an average of 7.8 years (n=78). Women were evaluated by questionnaire, psychophysical testing, and clinical examination to determine any abnormalities in visual function and the comparative prevalences of corneal, lens, retinal, and optic nerve pathology. RESULTS: There were no cases of vision-threatening ocular toxicity among the tamoxifen-treated participants. Compared with nontreated participants, the tamoxifen-treated women had no differences in the activities of daily vision, visual acuity measurements, or other tests of visual function except for color screening. Intraretinal crystals (odds ratio [OR]=3.58, P=.178) and posterior subcapsular opacities (OR=4.03, P=.034) were more frequent in the tamoxifen-treated group. CONCLUSIONS: Women should have a thorough baseline ophthalmic evaluation within the first year of initiating tamoxifen therapy and receive appropriate follow-up evaluations.

Aged↗

PubMed2002

Severe keratomycosis secondary to Scedosporium apiospermum.

PURPOSE: To report an unusual case of severe keratomycosis caused by Scedosporium apiospermum without any known previous ocular injury, that resulted in a corneal perforation, which was treated with an emergency penetrating tectonic keratoplasty and later with phacoemulsification and astigmatic keratotomy to restore good visual function. METHODS: A 45-year-old woman with a history of multiple sclerosis presented with a severe and refractory corneal abscess in her right eye without any known prior injury. Corneal scrapings were obtained and stained for microscopic evaluation. The samples were sent for aerobic and anaerobic bacterial and fungal cultures. RESULTS: Microbiologic examination of the corneal scraping showed Scedosporium apiospermum micelle. The fungal culture was sensitive to miconazole, itraconazole and voriconazole. Partial clinical improvement was achieved with hourly topical natamycin, amphotericin B, and systemic itraconazole application, although in vitro sensitivity tests showed resistance to the topical antifungal agents used. A corneal paracentral perforation occurred despite aggressive treatment. An emergency eccentric penetrating keratoplasty was performed with satisfactory results. Subsequent phacoemulsification and astigmatic keratotomy restored a good visual function. CONCLUSION: A fungal etiology should be suspected in a progressive and refractory corneal abscess. This report highlights the utility of microbiologic investigation to perform an early and accurate diagnosis. Aggressive medical treatment and even therapeutic penetrating keratoplasty to remove infected tissue could result in the maintenance of useful visual function. In view of the poor prognosis of this specific fungus, a closer observation and early keratoplasty might be required to preserve the ocular globe.

Abscess↗

PubMed1988

[Hemianopsia and agnosia].

Hemianopsia and agnosia, the coexistence of a disorder of perception and a disorder of recognition, is exemplified by two patients chosen for their clinical similarity. These two patients each had a stroke, one of the left and the other of the right posterior cerebral artery, resulting right and left hemianopsia respectively. Primary visual functions such as visual acuity and contrast sensitivity were intact. The differences were only apparent as regards the severity of the agnostic disorders. The patient with the lesion on the left failed to recognize stylized drawings, was alexic, could not lipread and was color anomic, but could easily identify handwriting, faces, and voices. The patient with the right posterior lesion could not recognize handwriting, was prosopagnosic and topographagnosic, but had no difficulty in reading, lipreading, or in recognizing stylized drawings. The apparent double dissociation of function demonstrates the presence of two different visual processing mechanisms which are very probably peculiar to the visual system of the left hemisphere in the one case and to that of the right hemisphere in the other. The authors' findings suggest that the two cerebral hemispheres differ fundamentally in the way they process visual information.

Agnosia↗

PubMed1983

Lexical decision time as a function of visual field and stimulus probability.

Two experiments were performed to study lexical decision time to word and non-word Hebrew trigrams as a function of stimulus probability, visual hemifield and responding hand. The results indicate that lexical decision time to words is shorter than to non-words. In addition, although decision time to words is significantly shorter with right hemifield stimulation than with left hemifield stimulation, decision time to non-words is the same whether they are presented to the right or left hemifield. Decision time to non-words decreases almost linearly as stimulus probability increases from 0.25 to 0.75, whereas decision time to words decreases in a concave manner apparently approaching an asymptote at a stimulus probability of 0.75. Responding hand is not significant as a main effect or in any interaction with any other variable. The data are discussed in terms of several models of hemispheric linguistic superiority.

Decision Making↗

PubMed1986

Functional vision in patients with neovascular maculopathy and poor visual acuity.

Central visual function is characteristically reported as Snellen acuity at distance and near. We performed functional tests in a group of patients with visual acuity of 20/100 or worse due to macular disease to determine whether there was a relationship between Snellen acuity and functional performance among these patients with poor visual acuity. Our tests of functional performance included currency discrimination, color recognition, reading a clock, and reading large print. Our results suggest that there is a correlation between Snellen acuity and functional vision, even among patients with poor visual acuity. Hence, therapeutic efforts to keep patients' visual acuity at 20/200 rather than 20/400, for example, appears to be justifiable in that better acuity levels seem to be associated with improved functional performance.

Aging↗

PubMed1976

Readability of approach charts as a function of visual acuity, luminance, and printing format.

This study determined the ability of 12 presbyopic subjects to read numerals from aeronautical approach procedure charts. The readability of chart numerals was determined for 15 size and contrast combinations as a function of near visual acuity (equivalent 20/20, 20/40, and 20/60) and chart brightness (100 and 1.0 ft L). Test subjects were evaluated at the normal near-visual-acuity level (20/20) and the minal near-visual-acuity levels (20/40) for Classes I and II and 20/60 for Class III) as specified in the FAA's Guide for Aviation Medical Examiners. The results indicated that subjects with 20/20 near visual acuity could read all chart numerals under bright and dim luminance conditions. Subjects with 20/40 and 20/60 levels of near visual acuity experienced reading difficulty under bright conditions and increased difficulty under dim luminance.

Aerospace Medicine↗

PubMed1989

The prognosis of patients with hysterical visual impairment.

During the period 1962-1986, 54 patients received the diagnosis hysterical visual impairment, i.e. 1 out of every 631 patients admitted to our department. Isolated visual acuity impairment was the most common symptom, followed by combined visual acuity impairment and visual field constriction, whereas isolated visual field constriction occurred most infrequently. The mean age of the patients in the first group was significantly lower than that of the patients in the latter group. A questionnaire sent to all patients in 1987 was answered by 41 patients. Twenty-one of these (51%) felt that their visual function now was good, whereas 20 (49%) claimed that their visual function was still poor. Nine patients (22%) were disabled because of their visual problems. Twenty-nine of the patients who answered the questionnaire were re-examined. Sixteen of these (55%) still showed visual impairment at the follow-up, while 13 (45%) showed complete disappearance of visual complaints. The younger patients appeared to have a better prognosis than the older ones.

Adolescent↗

PubMed2003

[Topographical evaluation on decentration of orthokeratology lenses].

OBJECTIVE: To evaluate the degree and correlative factors of decentration of orthokeratology lenses and its effect on the visual function. METHODS: Two different kinds of orthokeratology lenses were fitted to 270 eyes of 135 patients [initial mean refractive error: (-3.98 +/- 1.51) D]. Humphery Instruments ATLAS 8.0 was used for the computer-assisted analysis of corneal differential topographical maps. The examination of corneal topography was proceeded on the patients before the fitting of orthokeratology lenses and 6-month later. The distance from center of optic zone to apex of the cornea was measured as the value of decentration of orthokeratology lenses. The factors influenced the value of decentration were analyzed, including the initial refraction error, astigmatism, keratometry values, corneal eccentricity, and the diameter of the lens. The complaints of patients were recorded. Questionnaires, involving the symptoms of monocular diplopia and glare, were used to evaluate the effects of decentration of orthokeratology lenses on the visual function. RESULTS: The mean distance of decentration was (0.49 +/- 0.34) mm after one night fitting, the mean distance of decentration after follow-up for 1 month, 3 months and 6 months was (0.57 +/- 0.41) mm, (0.55 +/- 0.48) mm and (0.59 +/- 0.39) mm, respectively. After one month, the distance of decentration was less than 0.5 mm in 51.1% eyes, 0.5 - 1.0 mm in 35.6% eyes and more than 1.0 mm in 13.3% eyes. The direction of decentration in eyes with more than 0.50 mm decentration was mainly in the temporal side (48.5%). Patients with greater initial astigmatism and smaller diameter of lens showed greater distance of decentration (P < 0.05). There was no statistically significant difference in the distance of decentration between two groups with different corneal eccentricities and keratometry values (P > 0.05). The distance of decentration was greater in patients with monocular diplopia and glare. CONCLUSIONS: The degree of decentration of orthokeratology depends on the degree of initial refractive error, astigmatism and the design of orthokeratology lenses. The degree of decentration can influence the visual function.

Adolescent↗

PubMedDate not supplied

[Impairment of visual pathway function in right hemisphere in patients with arteriovenous malformation of the parietooccipital area of left hemisphere].

Marked arteriovenous malformation in the left parietooccipital area manifested only by symptoms of associative migraine involving changes of visual fields indicative of impaired functions of symmetrical compartments of the other brain hemisphere. Visual evoked potentials were changed in this patient because of dysfunction of both hemispheres and largely because of disorders in brain structures symmetrical to the site of arteriovenous malformation. This can be regarded as a manifestation of the so-called stealing phenomenon, when blood supply to one brain compartment is decreased because of excessive blood delivery to other regions of the brain. The results permit us to hypothesize regulation of blood supply to symmetrical compartments of brain hemispheres.

Cerebral Angiography↗

PubMed2003

[Measuring patient's quality of life in ophthalmology].

BACKGROUND: The assessment of patient's quality of life is not only of vital importance for clinical trials of new therapies but also becomes more and more implemented into daily clinical therapeutical decisions. METHODS: Different methods for evaluating quality of life are available. A well-known questionnaire for measuring global quality of life is the Short Form 36 (SF 36). However, in ophthalmology more specific instruments for measuring visual quality of life are needed. We review the usefulness of specific questionnaires such as the Visual Function 14 (VF-14) or the National Eye Institute Visual Function Questionnaire (NEI-VFQ) in their application to common ophthalmologic diseases such as cataract, age-related macular degeneration and glaucoma. Studies applying these methods were identified by a search in the Medline database. RESULTS: Several instruments to measure visual life quality in ophthalmologic patients are available. Internal consistency and validity are shown. CONCLUSIONS: Evaluating visual quality of life is an important parameter for assessing ophthalmologic diseases and the value of different therapies. It is an important outcome variable in clinical studies. Furthermore, individual visual quality of life should be considered in individual therapeutic decisions and helps to assess the economic effect of current and new therapies.

Aged↗

PubMed2001

An investigation of visual hallucinosis and visual sensory status in dementia.

INTRODUCTION: Visual hallucinosis occurs frequently amongst patients with dementia and there is some evidence of an association between hallucinosis and impaired visual function. This study examined the association between objectively rated visual acuity, ambient illumination levels and hallucinosis in patients with dementia. METHODS: Thirty dementia patients with visual hallucinosis plus 30 non-hallucinating dementia patients were recruited from referrals to community mental health teams in Leicestershire. Data were collected by means of a carer interview (including the Neuro-Psychiatric Inventory (NPI) and Clinical Dementia Rating Scale (CDR)), patient assessment (including Mini-Mental State Examination (MMSE) and measures of corrected visual acuity) and photometric assessment of the room most frequently occupied by the subject. RESULTS: Hallucinators and non-hallucinators did not differ significantly in respect of age, cognitive status or global dementia severity. Fifty per cent of hallucinators had a Snellen visual acuity of 6/24 or worse compared with 27% of non-hallucinators. Comparison of LogMAR transformed values for distance (Snellen chart) and near-vision (Sussex test-types) revealed significantly worse visual acuity for hallucinators on both measures (Mann-Whitney p < 0.05 and p < 0.01, respectively). Ambient illumination in the centre of the room under conditions of natural plus artificial lighting was significantly lower for hallucinating subjects than for non-hallucinators (median values 200 versus 345 Lux respectively; Mann-Whitney p < 0.05). CONCLUSION: These results are consistent with previous findings suggesting an association between visual hallucinations and poor visual acuity in patients with dementia, and introduce environmental illumination as another possible aetiologically relevant factor. Interventions aimed at improving visual function in this patient group now require evaluation.

Aged↗

PubMed1988

Visuoperceptual function in visual agnosia.

Two patients with visual agnosia underwent visual recognition and neuropsychological tests to characterize their perceptual functioning. Both had an initial "apperceptive profile" and evolved from cortical blindness. One had carbon monoxide intoxication and incidental agenesis of the splenium of the corpus callosum; the other had the clinical features of MELAS (mitochondrial encephalopathy, lactic acidosis, and stroke-like syndrome). The agnosia profile showed impaired object recognition but adequate visual matching and copying of unrecognized items. The patients were successful on form discrimination, mental rotation, and visuospatial skills, but did poorly on figure-ground discrimination, visual integration, facial discrimination, and constructional tasks. Their performances were characterized by slow, serial analysis of visual features and a decreased useful field of view. The pattern of results suggests a form of visual agnosia caused by disturbances of parallel distributed processing.

Adult↗

PubMed1993

[The topographic mapping of evoked bioelectrical activity and other methods for the functional neural visualization of the brain].

The paper is concerned with comparative characterization of brain functional imaging used in medicine today: bioelectrical activity mapping, assessment of spatial changes in cerebral blood flow by radionuclide and hydrogen clearance, NMR imaging, PET-scan, magnetoencephalography and thermoencephaloscopy. Original researches in neurosurgery clinic with the use of the mapping of evoked potentials enable the conclusion to be drawn about advisability of applying these methods in treatment and diagnostic practice. Besides, the mechanisms of compensation for higher mental functions in organic brain lesions are discussed.

Adolescent↗

PubMed1998

[Chronic visual hallucinations and illusions following brain lesions. A single case study].

Lesions of the visual system do not necessarily lead to deficits in visual function. In some cases, there may even occur Positive Spontaneous Visual Phenomena (PSVP) following cerebral damage. We present data from a male patient with continuous, long-term visual illusions after having experienced cerebral infarction at the age of 56. Basing on conventional Magnetic Resonance Imaging, lesions could be located in areas supported by the lateral and medial occipital artery. Initially, homonymous hemianopsia of the right visual field was found in perimetric examinations, but in the course of six months, visual function recovered completely. Ever since the incident, the patient has been suffering from permanent photopsia, intense colourful visual hallucinations and perseverations located in the former defective area which continued unabated even after the remission of his visual field defects. While many authors have published data on PSVP lasting for several seconds, usually vanishing completely within days or weeks after cerebral lesion, in our patient the symptoms continued over a period of so far nine months. Surprisingly, he was even able to make drawings of his illusions so that we were able to include some of his pictures.

Cerebral Infarction↗

PubMedDate not supplied

[Mechanisms of sensory function recovery in partial optic nerve atrophy before and after treatment with ampli-pulse phoresis].

Eighty-three patients (119 eyes) with partial optic nerve atrophy of different origin were treated by amplipulse phoresis and observed for 1 year. Based on the data of modern methods of examination of visual functions (changes in visual evoked potentials and achromatic static campimetry), the authors suggest that several mechanisms of visual function improvement underlie the therapeutic effect of amplipulse phoresis. These mechanisms are as follows: activation of the intact part of nerve fibers with restoration of myelin membranes, restoration of viability of nerve fibers in a state of parabiosis; a probable mechanism of visual acuity improvement is modification of the conduction of visual route on-channels, but this hypothesis needs further investigations.

Evoked Potentials, Visual↗

PubMed2004

Sensorimotor recovery following spaceflight may be due to frequent square-wave saccadic intrusions.

Square-wave jerks (SWJs) are small, involuntary saccades that disrupt steady fixation. We report the case of an astronaut (approximately 140 d on orbit) who showed frequent SWJs, especially postflight, but who showed no impairment of vision or decrement of postflight performance. These data support the view that SWJs do not impair vision because they are paired movements, consisting of a small saccade away from the fixation position followed, within 200 ms, by a corrective saccade that brings the eye back on target. Since many returning astronauts show a decrement of dynamic visual function during postflight locomotion, it seems possible that frequent SWJs improved this astronaut's visual function by providing postsaccadic enhancement of visual fixation, which aided postflight performance. Certainly, frequent SWJs did not impair performance in this astronaut, who had no other neurological disorder.

Astronauts↗

PubMedDate not supplied

Levodopa and childhood amblyopia.

A pilot study was undertaken to address the tolerance and efficacy of levodopa/carbidopa treatment for amblyopia in older amblyopic children who failed to respond to conventional occlusion therapy. Five amblyopic children, between the ages of 7 and 12 years, and two normal adults were given between 100 mg/25 mg and 400 mg/100 mg of levodopa/carbidopa, respectively, depending on body weight. A symptoms questionnaire was completed, with temperature, respiration, heart rate, and blood pressure taken periodically to assess tolerance. Blood samples were taken, via a heparin well, to assess the pharmacokinetics of levodopa, dopamine, noradrenaline, and DOPAC. Snellen visual acuity, contrast sensitivity, stereo acuity, and pattern VERs were measured periodically to assess efficacy. The results revealed a high prevalence of side effects including emesis and nausea (four of seven subjects). Pharmacokinetics revealed that maximum serum levels of levodopa occurred 30 minutes to 1 hour after drug ingestion and decreased by 50% after 2 to 4 hours. One hour after drug ingestion, Snellen visual acuity temporarily improved from an average of 20/159 to 20/83 in the amblyopic eyes. Contrast sensitivity and pattern VERs (10-minute checks) temporarily improved in both dominant and amblyopic eyes, whereas visual function remained stable in normal eyes. The improvements in visual function started to decrease 5 hours after drug ingestion. The results are discussed in the context of developing a therapeutic trial of levodopa/carbidopa for childhood amblyopia.

Adult↗

PubMedDate not supplied

Theoretical methods in the assessment of vision and automated perimetry.

An analytic understanding of automated perimetry requires an appreciation of the fundamental theories of vision and an understanding of the basic mathematical rudiments of signal processing theory. The theories of vision by Weber, Fechtner, and Stevens are evaluated and the mathematical bases of logarithmic, exponential, and power functions are considered as they relate to various models of visual functioning. Presenting perimetry results as actual, linear stimulus values, not theoretical, non-linear response values, could better allow clinicians to assess and examine the testing data directly to evaluate more correctly and accurately their patients' visual function.

Humans↗