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PubMed2001

Visual standards in a sample of dentists working within Scotland.

INTRODUCTION: This study aims to measure the visual acuity of practising dentists and to establish the average time elapsed since their last routine eye examination. MATERIALS AND METHODS: Distance visual acuity, near visual acuity, convergence, accommodation, contrast sensitivity, heterophorias and stereoscopic vision were measured in a diverse group of 46 dentists practising in Scotland. RESULTS: The results indicated that distance visual acuity was at least 6/6 for all but one of the subjects. All had acceptable near visual acuity. Accommodation followed the expected age-related trend of decreasing with age. No subjects had a definitely abnormal contrast sensitivity score although four were in the borderline zone. No subjects had a horizontal squint but two had a significant vertical phoria. Three subjects had no stereoscopic vision and one subject had a very high threshold level. All other subjects were able to see stereoscopically. Of the subjects 57% had been for an eye examination within the previous two years, with the range being from less than one month to 17 years. CONCLUSION: The eyesight of this group of clinicians exceeds generally accepted normal population values. Although the majority of the clinicians had attended for an eye examination within two years, the large range of time since last attendance is of concern and regular eye examinations are to be encouraged.

Accommodation, Ocular↗
PubMed2001

[Technical realization of an LCD-based vision test device].

We describe a computer-aided self-test vision screener for testing near and far visual acuity. The device generates images separately for each eye on a LCD. Acuity can be measured in the range between 0.1 and 1.6 for any distance between 0.34 m and 6 m. In addition, it also enables testing for colour deficiency, phoria, stereopsis and contrast sensitivity. The device is fully automatic and enables self-testing of the above mentioned functions. Initial practical application in an industrial environment has demonstrated the practicability of the device.

Diagnosis, Computer-Assisted↗
PubMed1975

Perception of less irregular and more irregular stimuli.

Berlyne's stimuli were presented in a stereoscope to test his hypothesis that Ss prefer the more irregular member of a pair of stimuli. 32 Ss, screened for normal acuity and phorias, were tested. Contrary to Berlyne's hypothesis and consistent with earlier stereoscopic studies, Ss tend to report more frequently the less irregular member of a pair of stimuli. These data can be explained by an information-conflict model; however, the clearest implication of this study was that experiments concerned with familiarity of stimuli should be qualified by the method.

Awareness↗
PubMed1994

An oculomotor test to measure alcohol impairment.

Drunk driving continues to be one of the nation's most serious safety problems. On the premise that oculomotor control provides a quantitative measure that is very sensitive to alcohol impairment, an oculomotor test previously developed as a portable hand-held Viewmaster viewer with specially designed grating patterns as images was used to stress the oculomotor system. Test scores decreased with increased alcohol impairment along with a large dependence on individual lateral phoria scores. Unfortunately, there was a large amount of interindividual variability, which may limit use of the test for the population at large unless other individual characteristics are included.

Adult↗
PubMed1982

Hemispheric sex differences in response to apparently moving stimuli as indicated by visual evoked potentials.

This research was designed to determine whether visual event related potentials (ERPs) recorded from over the two occipital hemispheres would indicate differential processing of apparently moving and stationary stimuli. Previous findings in the literature led us to consider a male-female comparison as part of our experimental design. Nine male and nine female subjects were screened for right-handedness and visual abilities (acuity, depth and phoria). Each participated in three experimental sessions over a three day period in which ERPs were recorded from O1 and O2 in response to stimuli presented in left, central and right visual fields. The main finding was that, for female subjects, right hemispheric derived ERPs were larger in amplitude than left hemisphere recordings for apparently moving stimuli presented centrally. Males showed no hemispheric amplitude differences. However, for male subjects, the left hemisphere ERP latencies to motion were longer than those recorded from over O2 with central visual field presentations. It was speculated that different attentional strategies in the two sexes led to the observed result.

Adolescent↗
PubMedDate not supplied

Postoperative exotropia.

One hundred fifty-four cases of infantile esotropia and acquired esotropia surgically treated before the age of seven were followed for a minimum of five years. We found 44% of infantile esotropia and 60% of acquired esotropia were converted to phoria with 20% having postoperative exotropia. Eight to 10 years of age seemed to be the turning point from esotropia to exotropia. Spontaneous decrease of accommodative convergence with age seemed to be the most important causative factor in relation to secondary exotropia. Long-term follow-up revealed the residual angle of deviation decreased with time and undercorrected esotropia resolved spontaneously. Therefore, it is the responsibility of the surgeon to encourage his patients to return regularly for follow-up visits even ten years after surgery for possible spontaneous change of deviation.

Adolescent↗
PubMed2005

[Acute concomitant esotropia and hysterical amblyopia].

CASE REPORT: The authors present the case of a 26-year-old woman, in her 29th week of pregnancy, who developed intermittent esotropia and diplopia. Six months later, the process was associated with visual loss and an accommodative spasm which did not improve with cycloplegia and refraction. The symptoms remained unchanged two years later. DISCUSSION: Acute concomitant esotropia may have no obvious underlying cause, but it has been associated with disruption of fusion, myopia, neurological problems and decompensation of a pre-existing phoria or monofixation syndrome. A physical or emotional debilitating illness may precede the onset of the problem. In our case, a neurologic origin was excluded and a diagnosis of hysterical neurosis and acute concomitant esotropia with hysterical amblyopia or functional visual loss was established.

Acute Disease↗
PubMed1976

Marathon running and vision.

Sixteen optometric tests were administered to 29 athletes prior to and following their running the 1974 26-mile B.A.A. Boston Marathon. The tests included amplitude of accommodation, near point of convergence, stereopsis, depth perception, near phorias, ACA, near ductions, peripheral fields, and suppression. It appears that the systemic fatigue did not significantly affect the test values and it is reasonable to assume similar findings for other forms of athletics. While few optometrists' or ophthalmologists' patients are marathon runners, this study's findings may be extrapolatable to more common conditions.

Adult↗
PubMed1976

Eye movements in heterophoria.

Reference is made to earlier reports by the author in which versional recovery eye movements were observed during the cover test in the non-occluded eye in case of heterophoria. This provided support for Hering's Law, although the magnitude of the versional movement did not relate to the degree of heterophoria. Recent studies of eye movements during the cover test on very small heterophorias have suggested there is a threshold value below which these versional recovery movements are absent, and that is presence depends on such factors as the size of the phoria, the degree of ocular motor dominance and patient concentration.

Eye Movements↗
PubMed2000

Heterophoria and fixation disparity: a review.

Heterophoria does not provide a reliable clue for ordering prisms in an asthenopic patient. The same reservation applies to associated phoria, as determined by prism correction of fixation disparity. Subjective tests for fixation disparity, even those with a fusionable fixation target, do not correctly indicate the vergence position of the eyes under natural viewing conditions. Attempts to measure fixation disparity on the basis of stereo disparity, using the "Measuring and Correction Methods of H.-J. Haase", have failed.

Eyeglasses↗
PubMed2000

Ophthalmologic abnormalities in mentally retarded.

PURPOSE: To determine the prevalence and types of ophthalmologic abnormalities in mentally retarded subjects. METHODS: Seventy-three institutionalized mentally retarded subjects (41 boys and 32 girls) aged 5 to 19 years (mean: 11.5 years) were examined ophthalmologically during a three month period (from May to July 1999). The eye examination consisted of visual acuity testing (illiterate Snellen E-chart or acuity card procedures), pupillary reflex and motility evaluation, cover test for phoria and tropia, examination of adnexa and anterior segment (magnifying glass or slit-lamp biomicroscopy if indicated and possible), retinoscopy and direct ophthalmoscopy. All subjects were evaluated pediatrically, neurologically, psychologically and otorhinolaryngologically if indicated. RESULTS: Ophthalmologic abnormalities were found in 60.2% of the subjects. Eyelid abnormalities accounted for 21.7%, fundus abnormalities for 21.6%, refractive errors for 15% and ocular motility disorders for 13.6%. Taken separately, optic atrophy (16.4%) was the most frequent disorder, followed by refractive errors (15%), hypertelorism (12.3%), epicanthus (10.9%) and nystagmus (8.2%). Strabismus and mongoloid obliquity of lids were seen in 5.4% each other while ptosis was disclosed in 4.2% of cases. Visual acuity tested in 60 subjects revealed that 25 (41.6%) had visual impairment. Of all subjects 10.9% required corrective glasses while 9.6% needed corrective surgery for strabismus and ptosis. CONCLUSION: This study shows a high prevalence of ophthalmologic abnormalities in mentally retarded subjects. This is in agreement with the results of several other previous studies. It's therefore essential to screen mentally disabled subjects ophthalmologically.

Adolescent↗
PubMed2003

[Progression of subjective refraction after artificial divergence surgery and its relation to a possible myopic spasm].

PURPOSE: To study the effect on subjective refraction of artificial divergence surgery in congenital nystagmus with blocking convergence. METHODS: Retrospective study on 139 cases, with a study of visual acuity and optical correction with habitual glasses 1-5 years after operation, according to age and ocular alignment (orthophoria or exophoria). RESULTS: Increased myopia with glasses of approximatively 1 diopter, but likely to be due to eye growth in this young population (mean age, 14 years). This myopic shift is higher in the exophoric population, but there is a tendency to prescribe a stronger correction to help control the phoria. A few rare cases of true myopic spasm were noted. CONCLUSION: After artificial divergence surgery, true cases of increased myopia were rare. Tonic vergence is stronger than accommodative vergence.

Adolescent↗
PubMed1992

The effects of pyridostigmine bromide on visual performance.

The effects of pyridostigmine bromide (PB) on selected visual functions were measured on four healthy aviator candidates. Following a pretreatment day during which baseline measurements were completed, subjects were administered currently recommended doses (30 mg, t.i.d.) of PB for 3 d during which their visual functions were assessed using a repeated measures design. Spatial resolution ability was evaluated with high and low contrast visual acuity charts and contrast sensitivity charts at three luminance levels. Dark adaptation was evaluated by measuring visual thresholds for 40 min after a standardized retinal photopigment bleach. Also, refractive error and several oculomotor functions (lateral phoria, fusional vergence, accommodative amplitude, and pupil size) were measured. On days that the subjects ingested PB, only refractive error and pupil diameter were significantly different, and these only minimally. We conclude that the use of PB at doctrinal doses will not significantly compromise an aviator's visual ability.

Accommodation, Ocular↗
PubMed1992

Asthenopia: frequency and objective findings.

Fifty young adults were interviewed about the asthenopic symptoms experienced in the preceding 6 months by means of a questionnaire; they then underwent ophthalmic investigation. We established the frequency of occurrence of single asthenopic symptoms and looked for their prevalence in subgroups determined by objective findings such as phorias, different accommodation widths, different fusional vergence widths, and others. The frequencies of single complaints were: headache 42/50 (84%), ocular pain 17/50 (34%), foreign body sensation 25/50 (50%), red eyes 22/50 (44%), photophobia 24/50 (48%), double vision 5/50 (10%), difficulties when changing fixation distance 21/50 (42%). We did not find any obvious preference for one of the symptoms in any of the subgroups mentioned above.

Adult↗
PubMed1992

Dynamic retinoscopy and accommodation.

The added positive lens power required for low and high neutrals at a distance of 1/3 m is determined as a function of age for a sample of 221 clinically normal subjects, aged between 10 and 80 years. These dynamic retinoscopy results are compared with corresponding laser optometer measurements of the levels of accommodation under each condition. Dark focus (tonic accommodation) measurements are carried out on a further sample of 58 subjects. Although the mean results of dynamic retinoscopy agree with those found by earlier authors, on the basis of our sample it is concluded that the considerable scatter in neutral values found in normal subjects at any age limits the usefulness of the technique as an indication of abnormality in near responses. Much of this scatter in pre-presbyopic subjects appears to be related to individual variation in the level of tonic accommodation, although near phoria may also play some role.

Accommodation, Ocular↗
PubMed2005

[Effects of short-term VDT usage on visual functions].

OBJECTIVE: To evaluate the effects of short-term VDT usage on visual functions. METHODS: Visual function of the video display terminal (VDT) operators before and after 1 hour VDT usage were assessed. These included refraction, amplitude of accommodation, near point of convergence, AC/A, phorias, fusional convergence and divergence, tear film break time (BUT) and aberrations. And the same situation was compared was the non-VDT usage. RESULTS: In comparison with pre-VDT use, amplitude of accommodation, BUT were significantly decreased (P < 0.05), near point of convergence, near lateral exophoria were significantly increased after VDT use (P < 0.05). Total, high order, 4th and 5th order aberrations were significantly greater after VDT use (P < 0.05). CONCLUSIONS: Short-term VDT work does have a significantly greater temporarily effect on visual function, tear film quality and visual quality.

Adolescent↗
PubMed2005

Aniseikonia testing in an adult population using a new computerized test, "the Aniseikonia Inspector".

PURPOSE: To determine the measurement characteristics of a new computerized test, the Aniseikonia Inspector Version 1, on a sample of clinic patients. METHODS: Aniseikonia was measured in the vertical, horizontal, and oblique meridians on 320 patients (mean 55 years old, range 17-89 years) prior to their optometric exam using the psychometric methods programmed into the Aniseikonia Inspector Version 1. Statistical analyses were performed to determine the distribution of aniseikonia in the sample of patients and the relationships between the amount of aniseikonia and patients' habitual refractive correction, visual acuity, stereopsis and binocular alignment status. The characteristics of the individual measurements were also examined. RESULTS: The means and standard deviations of the measured aniseikonia in the vertical, horizontal, and oblique meridians were -0.5% (2.5%), -0.1% (3.3%) and 0.3% (2.8%) respectively. The means in the vertical and oblique meridians were significantly different from 0.0 (p=0.0001, p=0.0314) while that in the horizontal was not (p=0.61). The distributions of aniseikonia showed that 65.6%, 57.5% and 64.3% had within +/-1.0% aniseikonia in the vertical, horizontal and oblique meridians, respectively. Correspondingly, 16.9%, 25.6% and 25.8% had aniseikonia of +/-3.0% or greater. The discrepancy between these percentages and those expected in a normal distribution indicate that the distributions were significantly more peaked than a normal distribution. This departure from normal is due to a few extreme values in the tails. The magnitude of aniseikonia had no statistically significant relationship with the patients' habitual refractive correction, visual acuity or stereopsis. The effect of phoria on the amount of aniseikonia was significant, more so for measurements in the horizontal meridian. The individual measurements, which are the average of two trials using the method of adjustment, showed no significant bias, no relationship between the means and differences in the two readings, but large differences between the two readings. Measurements in the vertical direction seem to be more stable than those in the other two meridians. CONCLUSION: As measured with the Aniseikonia Inspector 1.0, the majority of the patients sampled in this study exhibited 1.0% or less aniseikonia and were therefore not likely to have symptoms related to aniseikonia. At least 17% of patients had 3.0% or greater aniseikonia measured in the vertical meridian. The Aniseikonia Inspector warrants further evaluation in a clinical setting because of the large limits of agreement between the two settings that are average to determine the magnitude of the aniseikonia. These limits differ considerably from those established by the designers and, therefore, raise questions regarding the actual resolution of the instrument as compared to the nominal resolution.

Adolescent↗
PubMed2006

Chiari 1 malformation presenting as strabismus.

INTRODUCTION: Strabismus has been previously reported as a rare presenting feature of the Type 1 Chiari malformation. CASE REPORTS: We report a case series of twelve patients with Chiari 1 malformations with either strabismus or diplopia as part of their initial presentation. Ten patients had diplopia at the time of presentation, while 2 young children (ages 2 and 6) presented with esotropia without complaints of diplopia. Of the 10 patients with diplopia, 7 were constantly or frequently tropic while 3 had symptomatic phorias. One or more unusual features of the strabismus led to further investigations and the diagnosis of Chiari in these patients. The most common oculomotor disturbance was a comitant esotropia. Most patients were managed with prism glasses. One patient had strabismus surgery as primary treatment with early orthotropia. Three patients underwent neurosurgical decompression, with minimal improvement of their strabismus; one of these underwent subsequent successful strabismus surgery. CONCLUSIONS: Chiari 1 malformation may present with strabismus or diplopia as the major finding. Associated neurological features may be nonspecific (e.g., headache), subtle (e.g., gaze-evoked nystagmus), or delayed. Although neurosurgery may be required in some cases, primary strabismus management (surgical or prismatic correction) can be successful, particularly when strabismus is the lone (or sole specific) finding.

Adolescent↗