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PubMed1991

Distance and near readings of associated heterophoria taken on 500 patients.

Distance and near readings of associated heterophoria were taken, using standard Mallett units, on 500 patients passing consecutively through an optometric practice and any symptoms, connected with distance and near vision, were noted. Complete sets of results were obtained on 383 people. Distance readings, either in size or direction, did not appear related to symptoms and such readings did not appear helpful in patient management. For near vision a fair degree of association existed between readings of associated phoria and symptoms and it was possible in the under 40 years and 40-59 years age groups to express clinically useful rules regarding the relationship. Over 60 years of age such a relationship was complicated by the fact that high degrees of exophoria readings existed in both symptomatic and asymptomatic patients and it is suggested that this may be related to the quality of binocular vision.

Adolescent↗
PubMed1991

The effect of monovision lenses on the near-point range of single binocular vision.

Monovision (MV) contact lenses are commonly used to provide optical correction for presbyopia. Based on their review of the literature on fusional mechanisms, Erickson and Schor predicted that monocular blur associated with MV should not be sufficient to disrupt binocular fusion. We found that fusional vergence ranges in presbyopes corrected with MV were not substantially different from those measured under full binocular nearpoint correction. There were small but statistically significant tendencies for the phoria and base-in vergences to be less exo under MV conditions. Comparisons of findings between a group of successfully adapted MV patients and a group of patients who were unsuccessful with MV indicated no significant differences, suggesting that there is no adaptation effect for these performance variables and that these tests are not effective predictors of MV success.

Adaptation, Ocular↗
PubMed1990

[Refractive errors, strabismus and amblyopia in pre-school screening--experiences using a vision test in kindergarten].

UNLABELLED: Within the framework of mass screenings conducted by the Public Health service section for juveniles, 254 children were examined jointly on a voluntary basis in 5 different kindergartens. The examined children represented in each case 88% of the respective kindergarten groups. The examination programme included, among others, the R5 apparatus (visual acuity in respect of remote objects with and without + 1.5 D), Lang- and DeKa Stereo Test, Cover-and-Uncover Test with remote and near fixation, heterostatic retinoscopy (in 205 children only), ophthalmoscopic fixation test. In addition, the acceptance for U8 and the degree of care in respect of ophthalmological control and treatment were investigated. RESULTS: Strabismus or significant uncorrected errors of refraction were discovered by the on-target tests of covering and uncovering, fixation and retinoscopy in 26 of 205 completely examined children (12.7%). This had not been satisfactorily covered by single tests such as R5-Visus test with the criteria much less than 1.0 (grade 5) or much less than 0.7 (grade 4), respectively stereo tests. The combination of "R5-Test Visus much less than 1.0" and "DeKa Stereo Test not fully identified" attained a sensitivity of 81% with a positive predictive value of only 28%. This combination, therefore, results in too many healthy children being referred to the ophthalmologist. "R5-Test Visus much less than 0.7" and "DeKa Stereo Test not fully identified" attained a sensitivity of 75% with a positive predictive value of 44%. This combination is recommended as long as the R5 or R11 apparatuses are used. The phoria and stereo tests contained in the R5 apparatus are unsuitable for kindergarten screening.(ABSTRACT TRUNCATED AT 250 WORDS)

Amblyopia↗
PubMed1990

Prism adaptation and viewing distance.

Previous studies have shown that subjects with normal binocular vision adapt to prism-induced phorias. However, there are conflicting reports as to the amount of adaptation shown to horizontal prisms. Some investigations found a greater amount of adaptation to base out prisms compared with base in, whilst others found the reverse and one study found no adaptation to base out prism at all. This study investigated the adaptation response to horizontal prisms at distance and near in a larger number of subjects (n = 40). The results confirmed our previous findings and showed that at distance the adaptation responses are asymmetrical, there being a significantly greater amount of adaptation to base out prism compared with base in, whilst at near the responses are virtually symmetrical. Possible reasons for these findings are discussed.

Adaptation, Ocular↗
PubMed1977

Are visual anomalies related to reading ability?

Although reading ability is known to be related to a large number of factors, when a child having a reading problem is brought to an optometrist he (or she) has the responsibility of determining whether or not a visual anomaly may be a major or contributing cause of the reading problem. A review of the literature indicates that myopia is consistently associated with good reading performance; and that hypermetropia, astigmatism, lateral phorias, poor fusional vergences, strabismus and color vision anomalies tend to be associated with poorer than average reading performance. Well-designed and well-controlled studies are needed, particularly concerning the effect on reading ability of the correction of visual anomalies. Until such studies have been done, any child who has a reading problem deserves a thorough optometric or ophthalmologic examination and the correction of any visual anomalies found.

Astigmatism↗
PubMed1979

Aeromedical implications of the X-Chrom lens for improving color vision deficiencies.

A red contact lens (X-Chrom lens) worn on the nondominant eye by 12 color-defective subjects caused significant improvements on the Dvorine, Ishihara, and Hardy-Rand-Rittler pseudo-isochromatic color plate tests. Color vision scores on the Farnsworth Lantern, Color Threshold Tester, and Aviation Signal Light Gun were not improved. Minimal changes were found on the Farnsworth D-15 test, aeronautical chart color identification task, visual acuity, phoria, and stereoscopic depth perception. Control and color-defective subjects perceived a change in the path of a pendulum (Pulfrich test) when viewing through the X-Chrom lens or a monocular red filter. The X-Chrom lens may require extended wearing before its optimum effect becomes apparent.

Adult↗
PubMed1988

Visual skills of athletes versus nonathletes: development of a sports vision testing battery.

The field of sports vision has a fundamental premise that athletes require superior visual abilities to succeed in their sporting activity. This study takes a scientific look at what appear to be sports-related visual abilities using a clinical battery of vision tests to compare the visual performances of athletes to nonathletes. Significantly better visual performances were found to exist in the athletic population for certain visual skills: vergence facility, saccades, visual reaction time, peripheral awareness and near point of convergence. The tests for accommodative facility, visual proaction time, span of recognition distance phoria and distance stereopsis did not yield a statistically significant difference between the groups. These results provide a foundation for the development of a research-based sports vision testing battery.

Adult↗
PubMed1988

Vision anomalies and reading skill: a meta-analysis of the literature.

We report a meta-analysis of studies of the relation of vision anomalies to reading skill. Meta-analysis is a quantitative technique for combining the results of multiple studies that reduces the subjectivity of literature reviews. The results of the analysis of 34 studies of vision anomalies and reading skill that met the criteria for inclusion in the meta-analysis showed that hyperopia, exophoria at near, vertical phoria, anisometropia, and aniseikonia are associated with below average reading performance. Myopia and esophoria and esophoria at far are associated with average and above average reading performance. Reduced visual acuity, astigmatism, esophoria at near, fusional convergence and divergence, strabismus, nearpoint of convergence, and stereopsis were not found to be associated with reading performance.

Depth Perception↗
PubMed1987

Binocular anomalies and reading problems.

This paper reviews and evaluates the research literature on the relationship of binocular anomalies to reading problems. The weight of the evidence supports a positive relationship between certain binocular anomalies and reading problems. The evidence is positive for exophoria at near, fusional vergence reserves, aniseikonia, anisometropia, convergence insufficiency, and fixation disparity. There is some weak positive evidence for esophoria at near and mixed evidence for stereopsis. The evidence on lateral phorias at distance is negative.

Aniseikonia↗
PubMed1985

Accommodative vergence and related findings for a Nigerian population.

Using clinical data, normative values of accommodative vergence and related tests are presented and compared to previously published data. The results are highly variable. The 'phorias are the most variable tests while positive relative accommodation (PRA) and the recovery values on the whole have moderate variability. Negative relative accommodation (NRA), pupil size, break and blur findings on average exhibit low variation.

Accommodation, Ocular↗
PubMed1984

Visually perceiving distance: a comment on Shebilske, Karmiohl, and Proffitt (1983).

Shebilske, Karmiohl, and Proffitt (1983) interpret their data as showing that (a) the reference tonus level of the extraocular muscles controlling vergence is affected by everyday conditions of close viewing, and (b) this naturally induced phoria affects the visual perception of distance under natural viewing conditions. We note that these interpretations do not fully concur with the data presented--for example, the second conclusion favorably conflates partial results from two separate experiments--and we identify a number of confoundings that reduce the likelihood that the reported inaccuracies in distance judgments were due to variations in efference.

Distance Perception↗
PubMed1984

Stereo-discrimination between diplopic images in clinically normal observers.

When retinal disparity exceeds the limits for fusion, the resulting images are perceived as diplopic. In a stereo test that allowed comparison of crossed and uncrossed disparity sensitivities, 74% of the subjects perceived convergent disparities more readily than divergent disparities. This asymmetric sensitivity to disparity did not appear to be related to measurements of phoria, vergence amplitudes, or clinical measurements of stereo acuity.

Depth Perception↗
PubMed1983

Ocular functions and incidence of acute mountain sickness in women at altitude.

The effects of altitude on a series of ocular functions were studied on seven expedition members, all women aged 23-53 years, during the first ascent of the 6798-m peak Brigupanth in the Indian Himalayas. The only consistent change was a decrease in convergence amplitude. The amplitude of accommodation remained stable among the younger climbers, but decreased markedly among the older ones as higher altitudes were reached. There also appeared to be a lessened vascular reactivity to the hypoxia of altitude in the older members. Stereoscopic vision was unimpaired at all altitudes tested and extra-ocular muscle balance remained unaffected in all but two members who had an increase in their baseline phorias. Two of the summit climbers developed retinal hemorrhages. There was an average weight loss of 5.4 kg during the climb, but general health was good. Symptoms of acute mountain sickness were noted infrequently, and there were only moderate changes in the menstrual cycle.

Adult↗
PubMed1983

An evaluation of the Cavitron Autorefractor 7 with contact lenses and non contact lens wearing patients.

The Autorefractor 7 is a microcomputor assisted electro-mechanical optical system recently introduced to the professions for the subjective measurement of refractive error, phorias, and accommodative capacity. In this study of 450 eyes, 150 were wearing hard contact lenses, 150 wearing soft lenses, and 150 habitually wore a spectacle correction. Comparisons involved only the subjective refractive feature of the instrument and indicated no predictable difference in the three groups. Comparison of the Autorefractor 7 and clinical subjective refraction with the phoropter, however, showed that the instrument is reliable in the majority of cases but has a tendency to overcorrect myopia and astigmatism.

Accommodation, Ocular↗
PubMed1982

Three binocularity evaluation methods.

Determining effort expended in binocular seeing is usually accomplished by equating dissociated phoria with total vergence ability. Fixation disparity testing by disclosing failure of precise binocular alignment is a second method which helps to assess both direction and quantity of prism power needed to accomplish alignment. Neither of these two methods delineates the foveal role as a sensory fusional lock in binocularity. The third is the Goodlaw test in which the exact focus of the eyes is disturbed through plus and/or minus lenses, provides this information and further directs therapy.

Adolescent↗
PubMed1995

Eclamptogenic Gerstmann's syndrome in combination with cortical agnosia and cortical diplopia.

Cortical blindness is defined as a loss of vision due to bilateral retrogeniculate lesions (geniculocalcarine blindness). Gerstmann's syndrome is a combination of disorientation for left and right, finger agnosia, and profound agraphia, alexia, and acalculia. It is due to a lesion in the left angular gyrus, situated at the confluence of the temporal, parietal, and occipital lobes. We report on a patient who suffered from severe underdiagnosed eclampsia and who developed bilateral extensive medial temporal, parietal, and calcarine ischemic infarctions during an eclamptic fit. In addition, ischemia destroyed the left angular gyrus. The combination of these lesions led to Gerstmann's syndrome with additional cortical agnosia and cortical diplopia. For the first few months following the ischemic insult, the patient had been cortically blind. Thereafter, the patient slowly regained a visual acuity of 0.1 in both eyes. She then experienced monocular and binocular diplopia. Her ocular motility was normal; there was no phoria or tropia. Monocular and binocular diplopia slowly became less severe over the following year. Now, 2 years after the incident, the patient has a visual acuity of 0.2 in both eyes and no double vision. However, the handicapping symptoms of Gerstmann's syndrome, which make leading a normal life impossible, have persisted--the patient still cannot cope alone, mainly due to the severe disorientation for left and right. The picture of cortical agnosia, cortical diplopia, and Gerstmann's syndrome is a very rare combination. Visual recovery and rehabilitation in cortical blindness are severely affected and made difficult by the symptoms of Gerstmann's syndrome. In our case the reason for such a dramatic clinical picture was eclampsia, whose prodomes had not been diagnosed in time.

Adult↗
PubMed1995

Vision profile of patients with mild brain injury.

BACKGROUND: Patients suffering from a traumatic brain injury (TBI) show many types of visual dysfunctions, including binocular, oculomotor, accommodative and visual field loss. This study evaluates the visual status of patients suffering a mild TBI. METHODS: The visual findings of a control group of 16 non-TBI patients are compared to the visual findings of 16 patients with documented mild TBI. Functions compared include symptomology, refractive status, stereopsis, ocular alignment by cover test, relative accommodation, pursuits, near point of convergence break and recovery, phorias at distance and near and vergence ranges at distance and near. RESULTS: Significant differences were found between the two groups in the areas of refractive status, near point of convergence break/recovery, near cover test, stereo acuity and base-in break at distance. There were also significant differences in symptomology, pursuit function, base-in recovery at distance, base-in break/recovery at near and base-out recovery at distance. CONCLUSIONS: In-depth visual evaluation of mild TBI patients is critical for documentation purposes as well as for possible treatment regimens.

Adult↗
PubMed1994

The role of stereopsis and early postoperative alignment in long-term surgical results of intermittent exotropia.

Despite the presence of good stereopsis, surgically corrected intermittent exotropes may show a gradual outward shift with time. The purpose of this study was to identify early factors that influence the success of corrective surgery. Sixty-seven consecutive patients treated surgically for intermittent exotropia (age range 1.9 to 76 years) constituted our final sample. Sensory status was evaluated with the Titmus stereotest. A successful surgical result was defined as phoria or intermittent tropia of +/- 10 prism dioptres or less for near and distance with maintained or improved stereopsis, 6 months or more after surgery. The average postoperative follow-up period was 3.3 (range 0.5 to 11) years. Good stereopsis (60 seconds of arc or better) was present in only 42% of the patients preoperatively and 61% postoperatively. The overall surgical success rate was 60%. Early overcorrection, defined as an esodeviation present within the first 4 weeks after surgery, caused a significant improvement in the success rate, to 79% (p = 0.03). Poor preoperative stereopsis combined with early overcorrection resulted in a further significant improvement in the surgical success rate, to 92% (p = 0.07). This suggests that poor preoperative stereopsis does not necessarily preclude, and may enhance, long-term alignment stability postoperatively. We suggest that it is peripheral rather than central fusion that keeps the eyes well aligned after surgery and prevents recurrence of the exodeviation.

Accommodation, Ocular↗