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PubMedDate not supplied

Is the type of VDT work important in asthenopia?

The Authors studied the relationship between visual fatigue (or asthenopia) and different types of work with display units on about 30,000 videoterminal (VDT) operators of the Italian telecommunication company. Visual fatigue was reported with data entry, data checking, word processing, dialogue enquiry, and various services. The Chi-square test showed that asthenopia was not related to any particular type of VDT work, comparing subjects working at the VDT for similar times each week. These findings provide further confirmation that the main factor determining visual fatigue in VDT operators is the amount of time spent at the display units.

Adult↗

PubMed1995

Protective filters in the prevention of asthenopia at a video display terminal.

In this work 25,064 employees were studied with the aim of investigating whether the video display terminal (VDT) equipped with filters reduces the incidence of asthenopia with reference to weekly time spent at a VDT and duration of work at a VDT. Analysis showed that the filters themselves do not reduce the occurrence of asthenopia consequent to various factors (refractive defects, time spent at a VDT, and monitors' characteristics).

Adult↗

PubMed2003

[Reduction of asthenopia-related to accommodative relaxation].

PURPOSE: We investigated experimentally the effect of accommodative relaxation by outward shift stimuli for accommodation on asthenopia. METHODS: Twenty female students fixed on optical outward-shift stimuli at accommodation for 2 min immediately after 15 min of a sustained task on a 3-D display. Before and after the trial task and the outward shift stimuli, their accommodative step response was measured and their subjective symptoms were assessed. The outward shift stimuli in the optical system, which was set on a refractometer, were presented by moving the target scenery images from far to near and near to far repetitively a round both eyes' far point position. At the same time as the accommodation measurements, the changes of refraction were recorded from the same eye. RESULTS: While looking at the outward shift stimuli, the refraction of 9 out of 20 subjects showed an outward shift and that of the other 11 subjects shifted inward. The post-trial value of contraction (from far to near) time of accommodative step response in the inward-shift group was markedly prolonged, from 0.86 s to 0.97 s (p = 0.043), and the post-trial accommodative power at the far target was shifted outward; from +1.21 D to +1.13 D(p = 0.048). The subjective symptoms of "ocular fatigue", "eye heaviness" and "eye dryness" also increased after the is(p = 0.0035, p = 0.0038, p = 0.0162, respectively). In the outward-shift group, however, no statistical changes were found. CONCLUSION: From these results, we suggested that accommodative relaxation produced by outward shift stimuli at accommodation is effective in reducing of asthenopia following the deterioration of accommodative functions.

Accommodation, Ocular↗

PubMed1992

[Convergence insufficiency and asthenopia].

22 cases with convergence insufficiency (CI) were presented here. It is found that there was an important relationship between CI and asthenopia. The causes clinical findings, diagnostic criteria, treatment of CI and relation with asthenopia were discussed.

Adolescent↗

PubMed2006

Association between occupational asthenopia and psycho-physiological indicators of visual strain in workers using video display terminals.

BACKGROUND: There is a body of scientific literature examining functional changes in vision due to video display terminals (VDTs). The aim of our study was to determine the relationship of functional visual strain and symptoms of asthenopia and to evaluate the association between subjective and objective indicators of visual strain. MATERIAL/METHODS: Four hundred four office workers with and without involvement in VDT work were included in the study. To evaluate visual strain we used a questionnaire for subjective complaints, evaluated the main ophthalmologic indicators, and measured psycho-physiological indicators. RESULTS: The questionnaire data showed that 88.5% of the VDT workers complained of various vision disorders. VDT workers who complained of worsened vision, redness of the eyes, eye pain, and diplopia during work were found to show more significant changes in the psycho-physiological indicators objectively reflecting strain of the vision analyzer. In the group of people with symptoms of asthenopia, the differences in the indicators of visual sensomotoric reaction, constancy of clear vision, and changes in the periods of clear and unclear vision were statistically reliably greater than in people without symptoms of visual strain. CONCLUSIONS: The subjective perception of visual strain related to VDT work was confirmed by ophthalmologic and psycho-physiological measurements. Changes in ocular and psycho-physiological function before and at the end of the workday are a good objective index of visual and central nervous system strain.

Asthenopia↗

PubMed1990

[Asthenopia and monitor characteristics].

An epidemiological survey on 30,000VDT operators has been carried out to evaluate the relationship between asthenopia and monitor characteristics. A VDU operator has been classified as asthenopeic if he complained about at least two of the following ten symptoms: headache, tearing, eye smarting, blurred vision, double vision, ocular itching, photophobia, blinking, nausea, eye heaviness. Visual discomfort has been related to 1) the presence of flicker; the possibility to regulate, 2) brightness, 3) height; and 4) inclination of monitor. Asthenopia has resulted statistically correlated to the presence of flicker and to the impossibility of regulating height and inclination of monitor for both sexes. The possibility to regulate monitor brightness has not determined a reduction of visual discomfort either in men or in women.

Adult↗

PubMed1993

[The 4-prism diopter base-in test in diagnosis of exophoria with asthenopia and compensation by accommodative convergence].

About 30% of our patients suffering from purely binocular asthenopia showed lower binocular than monocular visual acuity. Cover test examination revealed exophoria at near fixation, which could be regarded to be physiological. Furthermore, the Pola test as well as Graefe's prism diplopia test showed no pathological findings. When given 4 prism base-in, a better binocular acuity was achieved and exophoria at for distance fixation was revealed. Often the prisms base-in had to be increased slowly and an operative treatment was indicated in 80%. The test is described in detail and examples from typical case studies are demonstrated. The importance of the test for understanding asthenopia in cases with heterophoria is discussed.

Accommodation, Ocular↗

PubMed1979

Restricted lees screen fields in patients with asthenopia, with and without psychogenic disorders.

Lees screen restrictions of non-specific origin, including apparent restrictions of the SR, IR, and LR muscles, were reported last year by Labow et al. In this complementary study, the authors examined eight apparently healthy subjects who had no history of ocular or psychiatric problems, eight psychiatric patients, and eight who had had a CNS disorder or had suffered cerebral trauma. Comparison of the Lees screen findings, visual fields, and accommodative defects of these patients revealed significant restriction of the Lees screen fields in only those patients who had symptoms of asthenopia (including all in the third group). Thus, such restriction does not depend on emotional state.

Adolescent↗

PubMed2001

Effect of cumulative nearwork on accommodative facility and asthenopia.

PURPOSE: To investigate quantitatively in young adults the relationship between long-term cumulative nearwork, degradation of dynamic accommodative ability and the presence of asthenopic symptoms. METHODS: Subjects consisted of 87 young students and office workers between 18 and 31 years of age with uncorrected visual acuity of 20/30 or better in each eye. The amounts of nearwork, dynamic accommodative facility, and level of asthenopic symptoms were measured for each subject. RESULTS: Total cumulative nearwork time was negatively correlated with accommodative facility and positively correlated with the number of asthenopic symptoms. Furthermore, significant correlations were found between total nearwork time and blurred vision, and blurred vision and reduced accommodative facility. Moreover, the sub-category of "hours spent reading over the years" was found to be significantly correlated with decreased accommodative facility. CONCLUSIONS: The correlations suggest a relationship between cumulative amount of nearwork, decreased accommodative facility and asthenopia.

Accommodation, Ocular↗

PubMed2003

Effect of subjective and objective workload on asthenopia at VDU workplaces.

An ergophthalmological tool has been developed to investigate effects of subjective and objective workload on work-related visual complaints (asthenopia). In field studies on different visual display unit (VDU) workplaces effects of objective and subjective workload, work intensity, and work breaks (5-9 min/hour) could be found. It could be shown that during the first hours of VDU work, asthenopic complaints have the tendency to follow effective workload. With increasing working time the effect of a general and visual fatigue overlaps other reported visual complaints in the majority of cases.

Asthenopia↗

PubMed1981

Adaptation to prism-induced heterophoria in subjects with abnormal binocular vision or asthenopia.

In a previous study we investigated how normal subjects adapted to prism-induced heterophoria. In this study we have continued this work by investigating this phenomena in 15 patients with abnormal binocular vision and/or asthenopia. It was found that the majority of subjects lacked or had a deficient adaptation system to base-in and/or base-out prisms, but all except two subjects examined adapted normally to vertical prism. These results suggest that it may be possible to treat the horizontal adaptation system independently from the vertical one. Prism vergences, heterophoria measurements, and the presence of fixation disparity gave little indication of the adaptation ability of the subjects. Symptoms correlated well with adaptation ability.

Accommodation, Ocular↗

PubMed2006

[Effects of visual optical stimuli for accommodation-convergence system on asthenopia].

PURPOSE: We investigated the effect on eyestrain of optical stimuli that we designed for accommodation and convergence systems. METHODS: Eight female students were given optical stimuli for accommodation and convergence systems for 1.5 min immediately after 20 min of a sustained task on a 3-D display. Before and after the trial, their ocular functions were measured and their symptoms were assessed. The optical stimuli were applied by moving targets of scenery images far and near around the far point position of both eyes on a horizonal place, which induced divergence in the direction of the eye position of rest. In a control group, subjects rested with closed eyes for 1.5 min instead of applying the optical stimuli. RESULTS: There were significant changes in the accommodative contraction time (from far to near) and the accommodative relaxation time (from near to far) and the lag of accommodation at near target, from 1.26 s to 1.62 s and from 1.49 s to 1.63 s and from 0.5 D to 0.65 D, respectively, and in the symptoms in the control group after the duration of closed-eye rest. In the stimulus group, however, the changes of those functions were smaller than in the control group. CONCLUSION: From these results, we suggest that our designed optical stimuli for accommodation and convergence systems are effective on asthenopia following accommodative dysfunction.

Accommodation, Ocular↗

PubMed1989

[Asthenopia and objective ophthalmological findings in a population of 2058 VDT operators in Lombardy].

A large population of 2058 VDT operators from all compartments in Lombardia of a large national company was studied. An "ergophthalmological" questionnaire was administered to all subjects, followed by an ophthalmological-orthoptic examination. Ametropias showed a prevalence of 51.9%; the most common refractive defect was myopia followed by astigmatism and hyperopia. Heterophorias with bad or mediocre compensation had a prevalence of 4.1 and 11% respectively. The study of symptoms showed a frequency of 23.5% of intense asthenopic complaints and 21.1% of less severe and less frequent symptomatology. Asthenopia was significantly correlated (chi square) with sex, VDT exposure, refraction, presbyopia, and decompensated heterophorias.

Adult↗

PubMed1997

Bilateral striate cortex contusion presenting with cerebral asthenopia rather than cortical blindness.

We report a 22-year-old female with a history of contusion of bilateral occipital lobes at the age of 1 year. Magnetic resonance imaging confirmed severe lesion in bilateral striate cortices which should have resulted in cortical blindness. However, she displayed a fairly good visual function presenting only cerebral asthenopia and the restriction of the visual field. A positron emission tomography revealed that no areas other than the primary visual cortices responded to visual stimuli. Thus, her residual vision may be attributable to plasticity of the visual cortex in humans.

Adult↗

PubMed1964