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At least 649 records · Page 36Linked to original sources
PubMed1995

Is there a typical VDT patient? A demographic analysis.

BACKGROUND: The use of video display terminals (VDT) in the workplace is growing rapidly. Visual problems associated with computer use are increasing apace. Recognizing and addressing these needs are vital tasks for the optometric practitioner. This paper examines the demographics, prevalence of symptoms, and other work- and vision-related factors among VDT workers. Understanding the characteristics of a typical patient can aid in developing effective treatment protocols. METHODS: Twenty-two optometrists collected data from 324 patients who work on VDT screens for a minimum of 2 hours per day. A questionnaire was used to collect the data. Along with reporting the patients' dry manifest refraction results, the survey instrument also included a self-report of experienced symptoms. RESULTS: The prototypical patient, based on the total subject population, is a 38-year old, mildly myopic female who uses the computer screen about 5 hours per day. Average total VDT work experience is about 5 years. Most of the patients use full-color screens and sit between 21 and 22 inches away from the screen. A variety of visual symptoms is reported, with eyestrain (65 percent) and headaches (42 percent) being the most common complaints. CONCLUSIONS: Between 75 percent (results of this study) and 88 percent (reported by NIOSH) of patients who use a VDT regularly are likely to be symptomatic. This study has helped to identify the "typical" VDT user and the symptoms this user is most likely to report. The next step is to develop a diagnostic and treatment protocol by which optometrists can prescribe for and potentially prevent these computer-related vision problems.

Adolescent↗
PubMed1995

[Occupational ophthalmopathy].

The authors describe a syndrome diagnosed in workers who perform tasks requiring visual strain. The syndrome comprises worse visual control, discomfort in orbital area and characteristic changes of refraction and accommodation. The young people having emmetropia and myopia demonstrate temporary and later consistent increase of refraction, and the elderly ones--decreased refraction and early development of presbyopia. In both cases marked fall of accommodation was shown. The article suggests also a possible scheme describing pathogenesis of the syndrome.

Adolescent↗
PubMed1995

Characteristics of visual display units that may cause visual difficulties.

The physical characteristics of a visual display unit (VDU) are compared to those of paperwork, through a review of the literature. Certain display characteristics are shown to enhance visual performance using a VDU whilst others significantly decrease it when compared to using hard copy. Overall, display characteristics do not necessarily render VDU use more difficult than if doing similar visual tasks without using a VDU.

Accommodation, Ocular↗
PubMed1993

[The physiological and hygienic problems of the computerization of school instruction].

The paper gives the findings of the long-term computer study of the influence of the lessons with computer on the functional state of schoolchildren of different ages. Regularities in the change of the working capacity and the functional state of children under the influence of computer lessons have been determined. It has been shown that the adaptation to computer activity takes place according to age. Schoolchildren aged 7 and 10-11 years have a lot of difficulties in adaptation. The degree of fatigue depends on the conditions of the lessons with computer, on the display type, duration, maintenance and regime of the lessons. The differential hygienic regulations of the optimum continuous duration of the lessons with computer during educational and extra educational time.

Adolescent↗
PubMed1994

[Pathogenesis and treatment of accommodative disturbance].

Using a computer-assisted infrared optometer with a pupillograph, we tried to obtain basic understanding of accommodative disturbance and its by investigating tonic (dark focus) level of accommodation and quasi-static accommodative response. In normal volunteers in whom either visual fatigue, general fatigue, or drunkeness was loaded intentionally, myopic shift of refraction, increased refractive fluctuation, and miosis were induced in all cases but the effect on amplitude of accommodative response was minimal. Subjects that worked at a computer terminal all day for 2 years, but not controls, developed myopic change at a statistically significant level. The effect on tonic level of accommodation of subject age, sustained near-vision tasks, and topical application of autonomic-related drugs was investigated. In subjects with severe eyestrain, myopic shift of tonic accommodation and prominent pupillary unrest were observed, suggesting increased parasympathetic excitation. One patient who was accidentally exposed to diisopropyl fluorophosphate, a potent cholinesterase inhibitor, showed a phenomenon similar to that mentioned above. Chaos attractors based upon the Shil'nikov phenomenon were introduced for evaluation of microfluctuation and pupillary unrest, as first applied by Sumida et al. Topical application of low-dose cyclopentolate hydrochloride was effective for treating accommodative abnormality in professional computed workers, who sometimes develop abnormal parasympathetic excitation. Based on quasi-static accommodation measurements, accommodative abnormality after head and neck injury, including whiplash injury, was divided into two completely different states: accommodative spasm and palsy. Since quasi-static accommodation was greatly affected by satellite ganglion block, sympathetic innervation from cervical ganglions may strongly influence accommodative response. Hyperthyroidism, which may be accompanied by sympathetic hyper-excitation, showed diminished accommodative response. In patients after refractive surgery by excimer laser, there was no difference in accommodative response before and after surgery, although tonic accommodation was slightly unstable after surgery. These findings suggest that the evaluation of tonic level or a similar state of accommodation and pupillary unrest will yield extremely valuable information in regard to various accommodative disturbances.

Accommodation, Ocular↗
PubMed1994

Double-masked placebo-controlled trial of precision spectral filters in children who use coloured overlays.

We selected 68 children who reported benefit from individually chosen sheets of coloured plastic placed upon the page when reading, and who used these regularly without prompting. These children viewed text illuminated by coloured light in an apparatus that allowed the separate manipulation of hue (colour) and saturation (depth of colour), at constant luminance. Many of the children reported improvements in perception when the light had a chromaticity within a limited range, which was different for each individual. A pair of plastic spectacle lenses ('experimental' lenses) was dyed so as to provide the appropriate chromaticity under conventional white (F3) fluorescent light. An additional pair was prepared having very similar colour but with a chromaticity outside the range in which perception was reported to improve ('control' lenses). Each pair was provided for 1 month in random order. The children kept diaries (36 completed) recording symptoms of eye-strain and headache. The children and those responsible for their assessment were unable reliably to distinguish 'experimental' from 'control' lenses. Nevertheless, symptoms were less frequent on days when the 'experimental' lenses were worn (P < 0.003).

Adolescent↗
PubMed1994

Reinvention of visual fatigue: accumulation of scientific knowledge or neglect of scientific history?

The development of science is believed to be a continuous accumulation of knowledge, giving rise to the somewhat false idea that the most recent knowledge is the most valid and most appropriate. Neglect of the history of a scientific discipline might therefore lead to reinvention of theories that have already been proposed and experimentally investigated. In the case of visual fatigue the pioneering works of Lucien Howe, Walter Lancaster and others at the beginning of this century are very similar to contemporary work in terms of conceptual definitions, methodological approach, assessment and results. The temporal and dynamic aspects of accommodation and vergence considered important today were intensely studied and discussed by Howe and others.

Asthenopia↗
PubMedDate not supplied

[The standardization of near visual acuity].

The determination of close visual acuity is done accurately if the vision exam at a distance of 40 cm is standardized and if an exact estimation of the near visual acuity for professional activities of normal people and people with bad visual acuity can be made. The model of an optotype for near vision, Snellen metric type, using the Jaeger notation from 1 to 16 and also the standardized point system from 3 to 36, is presented. A professional selection of people with bad visual acuity after near visual exam is also presented.

Asthenopia↗
PubMed1994

[Objective evaluation of visual strain in computer screen and office work by recording visually evoked cortical potentials (VECP) and determining changes in contrast sensitivity and refraction].

Visual evoked cortical potentials (VECP) elicited with checkerboard pattern reversal stimuli of high spatial frequency and low contrast were recorded. The changes in the VECP depending on the duration of task-oriented activity at video display units (VDU) and in the office were determined. The testing procedure can be used to decide on adequate recovery periods (breaks) for any visual workload and requires only a short time. We investigated 30 probands: 10 subjects tested before and after 4 h of VDU work under controlled standard conditions had statistically significant increases of latency (P < 0.001) and decreases of amplitude in VECP recordings (P < 0.05). Another 10 subjects tested at the same intervals but exposed to standard office working conditions also showed statistically significant increases of latency (P < 0.0001) and decrease of amplitude in VECP recordings (P < 0.01). The 10 control subjects tested at the same intervals spent the time between recording sessions on leisure activity (walking) and showed no significant VECP changes. Statistical evaluation was performed with Student's t-test for paired samples. Contrast sensitivity (Ginsburg test) decreased in both VDU and office groups after completion of their workload, but remained within normal limits. The maximal changes in refraction amounted to +/- 0.25 D after 4 h and +/- 0.5 D after 6 h and showed no bias. Extended periods of working at VDUs and conventional office work increase the latency and decrease the amplitude of the pattern-evoked VECP. This method can be used to determine optimal scheduling of breaks in for people working at VDUs and doing conventional office work.

Adult↗
PubMed1994

[Asthenoptic complaints in conjunction with illumination by gas discharge lamps].

Asthenopic complaints frequently occur when visual requirements are high in conjunction with illumination by gas discharge lamps. Four causes should be considered: level of the vision task, quality of light (spectral distribution, fluorescent flicker), quality of illumination, individual characteristics of the affected subject. Of 3000 patients, 58% had asthenopic complaints when exposed to gas discharge lamps. The number of females was twice that of males. The subjects affected were predominantly women, aged 20-30 years, who exhibited autonomic lability. Also, they showed reduced concentration power, diminished binocular and stereo vision, and more than normal photic driving findings in the EEG. Fluorescent flicker exerted no influence on elementary visual power, concentration power visuomotor performance, or optical reaction time. It did have an effect on dynamic visual acuity, flicker frequency, blinking rate, and the demands experienced. Fluorescent flicker should be reduced, e.g., by three-phase connection or electronic ballasts. Correcting the binocular vision and reducing the individual glare sensitivity are approaches indicated for individual therapy.

Adult↗
PubMed1994

[Measurement of pupillary unrest in subjects with nonspecific ophthalmic complaints].

Using a computer-assisted infrared optometer with a pupillometer, we studied pupillary unrest of 20 eyes of 20 patients suffering from nonspecific ophthalmic complaints, and of 20 eyes of 20 normal controls. The patient group had smaller mean pupil area than the control group (29 mm2 vs 38 mm2, p < 0.01), and showed prominent pupillary unrest and increased mean coefficient of variation (CV) of the pupil area (9.2% vs 3.4%, p < 0.001). Frequently, fairly long duration waves (longer than 1 sec) could be seen in the recordings of pupillary unrest in the patient group, but not in the control group. The patient group also showed significantly higher dark focus of accommodation than the control group (1.1 D vs 0.4 D, p < 0.01). These findings suggest that abnormal parasympathetic excitation may play a role in the etiology of continued nonspecific ophthalmic complaints.

Accommodation, Ocular↗
PubMed1994

The frequency of occurrence and severity of side-effects of immersion virtual reality.

Virtual reality (VR) has become increasingly well-known over the last few years. However, little is known about the side-effects of prolonged immersion in VR. This study set out to investigate the frequency of occurrence and severity of side-effects of using an immersion VR system. Out of 146 subjects, 61% reported symptoms of malaise at some point during a 20-min immersion and 10-min post-immersion period. These ranged from symptoms such as dizziness, stomach awareness, headaches, eyestrain and lightheadedness to severe nausea. These symptoms caused 5% of the subjects to withdraw from the experiment before completing their 20-min immersion period. Further research needs to be conducted that attempts to identify those factors that play a causative role in the side-effects of the VR system, and that looks for methods of reducing these side-effects.

Aerospace Medicine↗