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PubMed1988

Review of computerized orthoptics with specific regard to convergence insufficiency.

Traditional vision training or orthoptics has used line or contour targets to eliminate suppression and improve vergence performance. Manipulation of these stimuli is slow and arduous. Line stimuli require an experienced doctor/technician to interpret responses. Recently, automated vision training using microprocessor anaglyph stimuli, i.e., random dot stereograms (RDS), has been used in an operant conditioning paradigm. This technique has improved motivation of the patient, improved reliability, and provided standardization of therapy. In addition, the utilization of RDS associated with operant conditioning has been shown to improve vergence performance and to reduce asthenopia in the convergence insufficiency patient.

Accommodation, Ocular↗
PubMed1992

Clinical implications of vergence adaptation.

Placement of a prism in front of an eye results in a change in the tonic position of the eyes, a shift in the forced fixation disparity curve, and a shift in fusional amplitudes. These changes remain in effect as long as motor fusion is maintained. Elimination of fusion by occlusion or by removal of the prism results in a slow movement of the eyes back to the preprism position. This phenomenon, known as prism adaptation or slow fusional vergence, has important clinical implications in maintaining binocular vision with anisometropic prescriptions, age-related physiological changes in the positions of the eyes, blinking, high phorias, etc. Vergence adaptation is useful in explaining previous discrepancies between alternate and unilateral cover test, pre- and postorthoptic ACA ratios, stimulus and response ACA ratios, changes in phorias after orthoptics, and the observation of patients "eating up prism." Vergence adaptation anomalies have been implicated in causing asthenopia. Adaptation has been shown to change after orthoptic therapy. This paper reviews the clinical findings associated with vergence adaptation.

Adaptation, Ocular↗
PubMed1994

Effect of pattern glare and colored overlays on a stimulated-reading task in dyslexics and normal readers.

Scotopic sensitivity syndrome or the Irlen syndrome describes symptoms of asthenopia anamolous visual performance experienced while reading that are lessened by colored filters. One putative explantation for this condition relates to pattern glare: a hypersensitivity to repetitive patterns, including lines of print on a page. Experiment 1 used a placebo-controlled paradigm to investigate the effect of pattern glare and colored overlays on performance at a simulated reading visual search task. Despite the fact that the subjects were university students, the results showed a tendency, of border-line significance, to support the conclusion that colored filters seem to improve reading through ameliorating pattern glare. In experiment 2 we compared the prevalence of pattern glare in matched groups of dyslexic children and good readers. The dyslexic group reported more pattern glare, but also reported more glare from a control stimulus. Pattern glare in the dyslexic group was directly correlated with flicker sensitivity. The results are related to recent research on visual processing and ocular-motor function in dyslexia.

Adult↗
PubMed2000

Accommodative and vergence findings in ocular myasthenia: a case analysis.

Myasthenia gravis (MG) is a neuromuscular disorder that affects skeletal muscles, in particular, the extraocular muscles. Response variability is a hallmark sign. Detailed findings are described in a patient with MG in which the presenting sign was accommodative insufficiency. Objective accommodative findings were recorded 3 years before the onset of myasthenia, soon after the initial diagnosis was made, and then after the treatment commenced with pyridostigmine. In addition, clinical measurements were obtained periodically at different times of the day for various binocular motor functions, including near point of convergence, phoria, fusional and accommodative amplitudes, and relative accommodation. The disease adversely affected all accommodative and vergence findings, with fatigue being the primary disturbance. The therapeutic administration of pyridostigmine improved static measurements of accommodation and vergence and reduced asthenopia. The objective dynamic measurements of accommodation, vergence, and versions were less affected. These findings provide a clear demonstration that both intrinsic and extrinsic ocular muscles may be affected in the prepresbyopic myasthenic patient.

Accommodation, Ocular↗
PubMed1993

Accommodative and pupillary responses to sinusoidal target depth movement.

We evaluated the accommodative and pupillary responses to sinusoidal target depth movement in 10 normal subjects and one patient by analysing frequency responses and associated Bode plots. The phase of the pupillary response significantly lagged behind that of accommodative response, which suggests that they are controlled by separate central nervous systems. We measured the baseline shift of each response trace using a regression line and found that they were larger at higher stimulation frequencies. A patient with severe asthenopia showed a considerable baseline shift in accommodative response. These analyses may be useful for the quantitative assessment of dynamic accommodation and pupillary response.

Accommodation, Ocular↗
PubMed2006

Accommodation and the relationship to subjective symptoms with near work for young school children.

The aim of this work was to study the relation between subjective symptoms at near and ocular accommodation in terms of the amplitude of accommodation and the relative accommodation. A secondary aim was to discuss the diagnosis of accommodative insufficiency. The chosen cohort was examined on two occasions with 1.8 years in between. The first examination included 72 children, 43 boys (mean age 8.1 years, ranging from 5.8 to 9.8) and 29 girls (mean age 8.3 years, ranging from 6.2 to 10.0). The second examination included 59 of these children, 34 boys (mean age 9.9 years, ranging from 7.8 to 11.7) and 25 girls (mean age 10.1 ranging from 8.0 to 11.8). Subjective symptoms at near work (headache, asthenopia, floating text, facility problems) were recorded and the amplitude and the relative accommodation, both positive and negative, were measured. The result from the questionnaire showed that at the first examination more than one-third of the children (34.7%) reported at least one subjective symptom when doing near work and 42.4% at the second examination. No symptoms were found among children younger than 7.5 years, but for children between 7.5 and 10 years old at the first examination, the prevalence of at least one symptom was 47.2%. At the second examination, symptoms were reported also for the youngest children, i.e. from the age of 8 years. The discrimination ability for the amplitude of accommodation, both monocular and binocular, was significant. In the first examination the difference between the mean for the two groups (i.e. with and without at least one symptom) was around 2.00 D monocular and 3.00 D binocular. Corresponding figures from the second examination was a difference between the mean for the two groups of around 3.50 D monocular and nearly 4.00 D binocular. We suggest that accommodation measurements should be performed more routinely and regularly, maybe as screening, especially in children over 8 years of age.

Accommodation, Ocular↗
PubMed1999

Sequelae of sarin toxicity at one and three years after exposure in Matsumoto, Japan.

In order to clarify the later sequelae of sarin poisoning that occurred in Matsumoto City, Japan, on June 27, 1994, a cohort study was conducted on all persons (2052 Japanese people) inhabiting an area 1050 meters from north to south and 850 meters from east to west with the sarin release site in the center. Respondents numbered 1237 and 836 people when surveys were conducted at one and three years after the sarin incident, respectively. Numbers of persons with symptoms of sarin toxicity were compared between sarin victims and non-victims. Of the respondents, 58 and 46 people had symptoms associated with sarin such as fatigue, asthenia, shoulder stiffness, asthenopia and blurred vision at both points of the survey, respectively. The prevalences were low; some complained of insomnia, had bad dreams, difficulty in smoking, husky voice, slight fever and palpitation. The victims who had symptoms one year after the incident had a lower erythrocyte cholinesterase activity than did those who did not have symptoms at the early stage; such persons lived in an area with a 500 meter long axis north east from the sarin release site. The three-year cohort study clearly showed that the odds ratios of almost all of the symptoms were high in the sarin-exposed group, suggesting a positive relationship between symptoms and grades of exposure to sarin. These results suggest that symptoms reported by many victims of the sarin incident are thought to be sequelae related to sarin exposure.

Adult↗
PubMed1996

Psychology of computer use: XXXVI. Visual discomfort and different types of work at videodisplay terminals.

The relationship between visual discomfort (or asthenopia) and different types of work using display units for 10,626 videodisplay terminal operators of the Italian Telecommunication Company was studied. Visual discomfort was evaluated as related to data entry, data checking, word processing, dialogue, enquiry, and various services. Chi-squared indicated that visual discomfort was not significantly related to any particular type of work for subjects with similar amounts of weekly time using videodisplay units. These findings are consistent with earlier results indicating that the main factor determining visual fatigue in VDT operators is the amount of time spent on the display units.

Adult↗
PubMedDate not supplied

Accommodation deficiency in healthy young individuals.

Ten patients, ages 10 to 19, with accommodation insufficiency are reported. All patients were in good health and asymptomatic, except for asthenopia during near visual activities. Each patient's amplitude of accommodation was measured and found to be considerably below the minimal normal for their respective ages (an average of 6 diopters). Only three patients had associated convergence insufficiency. No etiology for the diminished accommodation was suggested by history or could be identified by careful examination. All patients were successfully managed optically with bifocals or reading glasses, although three required the addition of base-in prisms for the near exodeviation. Near vision testing and determination of the near point of accommodation should be part of the pediatric ophthalmologic examination in all patients with complaints referable to their reading and visual performance at near.

Accommodation, Ocular↗
PubMed2002

Objective improvement from base-in prisms for reading discomfort associated with mini-convergence insufficiency type exophoria in school children.

PURPOSE: To determine whether base-in prism glasses could diminish asthenopia, and improve reading abilities (speed, accuracy and comprehension). METHODS: All patients aged 8-18 years, from one practice, were examined and considered prospectively over a six month period. Ten percent (72) of these 703 patients met initial criteria of an exodeviation greater at near than distance and reading discomfort. At initial examination these 72 were asked to read orally, with and without base-in prisms. If the senior examiner noted they read faster and with fewer mistakes, and the patient reported increased reading comfort, then reading (only) glasses with 2 to 3 diopters base-in prism OU were prescribed. Of the 72, 33 were so treated. After 3 weeks they were given the Gray Oral Reading Test (GORT-3). This test has two equal parts which were administered one with, and one without, prisms. A subjective questionnaire was also administered. RESULTS: The overall mean improvement in reading speed, accuracy and comprehension on the GORT- 3 with base-in prisms, was from the 34th to the 66th percentile. The improvements in reading were "statistically significant" at p<.001. Patients also reported subjective improvement in asthenopic symptoms and headaches. CONCLUSION: Base-in prism glasses improve subjective reading comfort and abilities (speed, accuracy and comprehension) in these patients.

Adolescent↗
PubMed1992

The effect of sleep deprivation and sustained military operations on near visual performance.

A group of military servicemen were deprived of sleep for 65 h while they carried out a simulated military mission with a high visual workload. Their performance in a series of near vision tests was monitored. In general, the visual system was found to be resilient to the stress of sleep loss, the subjects experiencing mild symptoms of asthenopia (eyestrain). However, after 48 h without sleep there was a reduction in amplitude of convergent fusional reserves and a decrease in contrast sensitivity to a spatial frequency of 6 cycles/degree. A disruption in diurnal rhythms for these parameters was suggested. The results are considered in terms of the maintenance of visual efficiency and comfort with loss of sleep, and have implications for both the military and civilians involved in shift work and long work schedules.

Accommodation, Ocular↗
PubMed2006

[Near triad measurement--accommodative pupillometry with horizontal eye tracking and its qualitative analysis].

PURPOSE: Recording of "near triad responses" was done by static accommodative stimulation to reveal the qualitative analysis of asthenopia. METHOD: Twelve healthy subjects in agegroups of 20, 30, and 40 years were examined before and after several hours of visual display terminal (VDT) work after informed consent. Three trials of forward <-> backward movement of focusing on a target were carried out. Response curves of horizontal eye tracking and pupillary diameter, that is, convergence with miosis and divergence with mydriasis, were recorded continuously, bilaterally and simultaneously by TriIRIS. RESULTS: 1) Normal patterns of vergence and pupillary responses with constant amplitudes were recorded in five subjects and were stable. 2 ) Gradual decline of the mydriatic peak was observed in two subjects, suggesting spastic accommodation. Increasing mydriatic peak or notching of mydriatic phase was seen in one eye each, suggesting tonic disaccommodation. These abnormal patterns were reversed by adequate refractive correction, and classified as an eye-fatigue group. 3) Abruption of miotic phase was observed in two cases of exophoria. 4) Low and declining amplitudes despite normal light response were observed in two subjects, suggesting debilitated accommodation, and they were classified as an eye-strain group. 5) Post-traumatic mydriatic anisocoria responded in parallel, suggesting paretic accommodation. CONCLUSIONS: Coordinated dynamics of near triad responses revealed remarkable characteristics of accommodative iris movements with vergence. These objective findings revealed the different patterns of functional disorder of accommodation.

Accommodation, Ocular↗
PubMed1991

Validation of the General Health Questionnaire in female video display unit (VDU) operators in Singapore.

Fifty-seven Chinese female Video Display Unit operators employed in a multi-national company were asked to complete the 28-item General Health Questionnaire (GHQ-28). This is part of a study on stress and asthenopia in this group of workers. Validity of the GHQ-28 was determined by comparison with the Clinical Interview Schedule (CIS). The GHQ-28 was found to give optimum results with a cut-off score of 5/6. The CIS classified 28.07% as cases and this was comparable to the estimated prevalence of 28.03% derived from the GHQ.

Adult↗
PubMed1990

[Accommodation insufficiency in children].

Insufficiency of accommodation in children is often misdiagnosed, and particularly in preschool age. Subject if symptoms are unspecific, asthenopia, difficulties in nearwork, and for concentration. Differential diagnosis must be done between dyslexia, non refractive accommodative esotropia with high AC/A. In some cases we can't exclude the possibility of myasthenia even if this subject is still in discussion. The authors report two clinical cases of hypoaccommodation in children.

Accommodation, Ocular↗
PubMedDate not supplied

[Status of the visual system in operators causing railway accidents].

One hundred and eighty four engine-drivers aged 21-60 years were examined; 91 from them provoked an accident not stopping the train in front of the "Stop" signal; 93 constituted a control group. Compared was the status of the visual system and the efficiency of the visual functions such as: binocular vision, color vision and asthenopia, mesopic vision and the sensitivity to glare. In engine-drivers of the "accident-prone" group one observed an increased sensitivity for glare. The authors suggest it would be necessary to introduce to the qualification examinations for engine-drivers the evaluation of the sensitivity to glare and of the visual ability in mesopic conditions.

Accidents, Occupational↗
PubMed1989

[Magnetic field on the deranged accommodation of visual detector terminal operators].

The effects of magnetic fields on the accommodation of operators engaged in visual display terminals (VDT) who complained of asthenopia and proved to have some abnormalities in the semistastic properties of accommodation were examined. Before and after loading a magnetic field of 400 Gauss or 2,000 Gauss on the eye, the quasistatic properties of accommodation were measured and compared. The quasistastic properties analyzed in this experiment were the maximum amplitude of accommodation and the gradient of accommodation that means a ratio of accommodative response to accommodative stimulus. Both factors were statistically improved in a dose dependent manner after loading the magnetic field, i.e. 2,000 Gauss was more effective than 400 Gauss concerning the improvement of accommodation. To exclude a psychogenic effects, simulated loading by a placebo which was an imitation magnet which did not produce a magnetic field was also applied to the patients, but no improvement was detected. Normal persons who were examined as controls showed no statistical change in the semistastic properties of accommodation after loading of the magnetic field. After examination of the semistatic properties of accommodation, refraction was also estimated by an autorefractometer, but no change was detected in either patients or controls. The magnetic field seemed definitely to have effects on the functionally involved accommodative system.

Accommodation, Ocular↗
PubMed1989

[The ophthalmic ergonomic characteristics of the visual apparatus of workers engaged in the assembly of computer memory elements on ferrites].

The paper analyses results of complex ophthalmic ergonomic examinations in 135 women occupied in assembling computer memory elements on ferrites--a work of the highest accuracy degree. It was found that in 2/3 of all the subjects, myopia was connected with the work in the shop. In almost 50% of cases, the work leads to complaints of asthenopic character. It is proved that in this kind of work asthenopia is connected with the weakening of the accommodation system of the eye.

Accommodation, Ocular↗
PubMed1987

[Evaluation of the usefulness of methods of diagnosing eyestrain].

The examinations have been carried out under model conditions in women aged 33.6 +/- 3.8, in whom refraction defects or other sight organ disorders had been excluded. In order to select factors that would be most sensitive and specific for evaluation of visual fatigue, variations in the following indices of the sight organ occupational condition have been analysed: the near vision point, dispersing lens tolerance, retina sensibility, critical fusion frequency, speed and accuracy of perception, visual simple and choice reaction time. The indices have been analysed under the performance of sigh work and medium-hard physical effort. Variations in the near point and retina irritability have been regarded the most sensitive and specific indices of asthenopia. In addition, intra- and interpersonal variability, as well as seasonal variability of the indices listed have been assessed. Significant seasonal differences have been found between the values measured in the persons prior to work in summer and winter for near vision sense point, dispersing lens tolerance, retina irritability, and critical fusion frequency.

Adult↗