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PubMed1994

Vision screening with the RDE stereotest in pediatric populations.

The usefulness of the Random Dot E (RDE) stereotest in screening the vision of school-aged children for vision problems has been established. As a single screening procedure, the effectivity (phi) of the RDE (phi = +0.52) is greater than the widely used Snellen acuity technique (phi = +0.36) and faster to complete. Very-low-birthweight (VLBW) children have a higher incidence of vision problems including strabismus, amblyopia, and refractive error than children born with normal-birthweights (NBW's). My purpose was to determine: (1) whether a group of young children at high risk for vision problems could perform random dot stereotesting and (2) an age appropriate pass/fail criterion for stereoacuity screening. Furthermore, categorization as pass or fail by each screening method studied [stereoacuity (RDE), visual acuity [Teller Acuity Cards (TAC) and Broken Wheel (BWA)] and refractive error] was compared for independent agreement with vision examination results. The subjects were a cohort of NBW and VLBW) (< 1500 g) children matched at birth for maternal age, ethnic origin, time of hospital birth, and parity. Results of a masked investigation of 30 children [VLBW (N = 10) and NBW (N = 20) children] tested at 3 years of age (mean age = 3.0 years, range 2.11 to 3.1 years) showed that (1) 86.7% were able to complete the 168 sec arc random dot stereoacuity task when a two-alternative forced-choice preferential-looking paradigm was used for testing, (2) the specificity and sensitivity were 88.2%, 76.9% (RDE); 81.2%, 64.3% (TAC); 52.9%, 92.3% (BWA); and 94.1%, 61.5% (refractive error), respectively, (3) the reliability the RDE stereoacuity screening was greater (k = +0.66) than any of the other procedures studied, and (4) there was 73.3% agreement on test-retest categorizations between observers.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗
PubMed2001

Vision screening in central Iowa.

This study assessed the vision-screening practices of all preschools and elementary schools during the spring of 2000 in the Heartland Area Education Agency (AEA) in central Iowa. Surveys were returned by 7% of the preschools and 56% of the elementary schools. Survey questions were drafted based on recommendations from the Iowa Vision Screening Program Guidelines, which were distributed to all Iowa school districts in 1997. Areas surveyed included vision-screening personnel, attainment of students' visual history, rescreening practices, referral and follow-up, and screening procedures. Survey results indicated that there is a need for improvement to standardize vision-screening procedures within Heartland AEA. Time and effort are invested in activities that are not recommended, and not enough effort is being put into recommended activities such as obtaining vision histories, rescreening to avoid overreferrals, and follow-up to make sure students receive required treatment.

Age Factors↗
PubMedDate not supplied

Assessing visual function in children younger than 1 1/2 years with normal and subnormal vision: evaluation of methods.

PURPOSE: Methods for detecting subnormal vision early in life are needed to adequately diagnose the condition and begin treatment and rehabilitation. METHODS: Forty-six children ages 1 month to 1 1/2 years with either assumed normal vision, visual impairment due to eye disease, or strabismus were examined with the following tests: Stycar rolling balls; preferential looking (Teller acuity cards); and the ability to detect raisins, puffed rice, and sugar strands on two different backgrounds, one white and one black. RESULTS: Children with visual impairment and strabismus often showed normal values for their age, and children with assumed normal vision sometimes had values below those established for normal development of vision with the Stycar rolling balls and the Teller acuity cards. CONCLUSIONS: It is not possible to use these tests to reliably differentiate among normal vision, visual impairment, or strabismus in children younger than 1 1/2. Not until recognition acuity, symbols, or letters can be tested can reliable results be obtained. However, the tests are useful to estimate the general visual function of children in this age group.

Contrast Sensitivity↗
PubMed2000

Near stereoacuity: development in preschool children; normative values and screening for binocular vision abnormalities; a study of 115 children.

PURPOSE: Because of controversial results in previous reports, we wished to further evaluate stereoacuity development in children with normal binocular vision, and to investigate the reliability of stereoscopic tests for screening for abnormal binocular vision and amblyopia. MATERIALS AND METHODS: In a prospective study, 115 children, age 3 to 6 1/2 years, were first tested on the TNO and Titmus Stereotests, after which they received a more complete eye examination to determine the presence of ocular and vision abnormalities. Only specific quantitative stereotest results were tabulated for the development study. RESULTS: Binocular vision anomalies were detected by stereotesting in 3 of the 115 children. Testability was better on the TNO than the Titmus Stereotest. Using only the quantitative stereotest results, when segregated by age groups, there was a "statistically significant" change (improvement with age) on the TNO Test (p=.0001)(x2); whereas there was no such improvement found on the Titmus Stereotest Circles, p=.045, 0.72. CONCLUSIONS: The TNO Test is reliable for screening for binocular vision anomalies and amblyopia. Also, normal stereopsis and stereoacuity acuity improves "significantly" between age 4 and 5 1/2 years, and reaches adult-like level at 5 1/2 years on this test.

Aging↗
PubMed1980

[Comparative evaluation of the usefulness of the methods of studying binocular vision for purposes of vocational guidance].

The deficiency of binocular vision calls for an absolute contraindication to perform a number of occupations. It is not easy to evaluate the binocular vision disturbance, especially in young people. Therefore it was decided to check the binocular vision by six methods and compare the results. Among 199 pupils of the seventh form of primary schools, the following binocular vision disturbances have been found: in 18% of subjects on stereometer, in 15% on a projector with polarizing glasses, in 14% lack of protective reflexes, in 13% on stereoscope, in 11,6% on synoptophore and lack of ambiopia after using the prism in 9% of subjects. All the tests yielded negative findings in 5,5% of subjects. The obtained data suggest that it is not enough to use just one method for a thorough determination of binocular vision.

Adolescent↗
PubMed1997

[Evaluation of some vision components after implantation of bifocal and monocular intraocular lenses].

Short and long distance vision as well as vision in twilight conditions and dazzle sensitivity in 2 groups of 30 persons have been compared. In one group Corneal-Dual bifocal intraocular lenses and in the other group monocular lenses were implanted. In the former group 0.75 or nearer vision acuity was obtained without any additional correction, while in the latter group obtention of such vision required additional correction to +/- +2 4.0 D sph. Vision in twilight conditions and dazzle sensitivity were similar in both groups, though clearly lower than normal. The study also presents indications and contraindications for implantation of bifocal lenses.

Adult↗
PubMed2005

Recent advances in color vision research.

The remarkable variation in color vision both among and within primate species is receiving increasing attention from geneticists, psychophysicists, physiologists, and behavioral ecologists. It is known that color vision ability affects foraging behavior. Color vision is also likely to have implications for predation avoidance, social behavior, mate choice, and group dynamics, and should also influence the choice of stimuli for cognitive experiments. Therefore, understanding the color vision of a study species is important and of particular significance to scientists studying species with polymorphic color vision (most platyrrhines and some strepsirrhines). The papers in this issue were inspired by a symposium held during the 20th Congress of the International Primatological Society at Turin, Italy, in August 2004. The aim of the symposium was to bring together research from a range of disciplines, using recent methodological advances in molecular, modeling, and experimental techniques, to help elucidate the evolution, ecological importance, and distribution of color vision genotypes and phenotypes. The symposium achieved its aim, and as with most research in expanding disciplines, there are surprises and many questions still to be answered. Further advances will be made using a combination of different approaches involving analyses at the level of molecu1es, types of cell and neural networks, detailed and long-term field work, modeling, and carefully controlled experimentation.

Animals↗
PubMed2005

Color vision pigment frequencies in wild tamarins (Saguinus spp.).

The adaptive importance of polymorphic color vision found in many New World and some prosimian primates has been discussed for many years. Polymorphism is probably maintained in part through a heterozygote advantage for trichromatic females, as such individuals are observed to have greater foraging success when selecting ripe fruits against a background of forest leaves. However, recent work also suggests there are some situations in which dichromatic individuals may have an advantage, and that variation in color vision among individuals possessing different alleles may also be significant. Alleles that confer a selective advantage to individuals are expected to occur at a higher frequency in populations than those that do not. Therefore, analyzing the frequencies of color vision alleles in wild populations can add to our understanding of the selective advantages of some color vision phenotypes over others. With this aim, we used molecular techniques to determine the frequencies of color vision alleles in 12 wild tamarin groups representing three species of the genus Saguinus. Our results show that allele frequencies are not equal, possibly reflecting different selective regimes operating on different color vision phenotypes.

Animals↗
PubMed1990

On the history of deformation phosphenes and the idea of internal light generated in the eye for the purpose of vision.

Deformation phosphenes are light sensations evoked by deformation of the eyeball in total darkness. They were first reported in Western literature by Alcmaeon of Croton in the fifth century B.C. The phenomenon of deformation phosphenes was instrumental in prompting some pre-Socratic philosophers and Plato to conceive the idea that efferent light is emitted from the eye for the purpose of vision and a 'cone of vision' is formed by interaction with the external light. In the theories of vision this cone of vision played an important role as a signal-transmitting structure and was also used by the Greek opticians as a geometrical construction to explain optical properties of vision. The impact of the deformation phosphene experiment on the ideas of visual sensation can be followed from Greek antiquity through the period of Roman dominance and Galen's medical teaching on to medieval times and up to the late Renaissance when, based on the anatomy of the eye as illustrated by Felix Platter, the image formation on the retina was correctly described for the first time by Johannes Kepler. In the generations following, deformation phosphenes were still employed as an important argument in defence of the theories of vision. However, the idea of physical light generated by eyeball deformation was rejected with increasing frequency during the 17th and 18th centuries. The literature on this topic is discussed, comprising the contributions of the Arabic philosophers and physicians of the 9th and 10th centuries A.D., the Franciscan and Dominican philosophers of the 13th century, Nicolaus Cusanus of the 15th century, several anatomists of the 16th and 17th centuries, Kepler, Plempius, Descartes, Boyle, Newton and others. After Kepler, the mechanical interpretation of the deformation phosphene being caused by direct action of the eyeball deformation onto the retina slowly became dominant, and the idea that physical light is generated in the eye disappeared. The experimentum crucis in this matter was performed by Giovanni Battista Morgagni (1682-1771) and repeated and extended by Georg August Langguth (1711-1782). On the basis of their results, the case for physical light being generated in the eye by deformation was refuted definitively and slowly vanished thereafter from scientific literature. Deformation phosphenes were used in the 19th and 20th centuries as an instructive example of the percepts evoked by inadequate stimulation of a sense organ. J.E. Pŭrkyne in particular contributed to the study of deformation phosphenes, and finally in 1978, F. Tyler devoted a careful study to the differences between monocular and binocular deformation phosphenes.(ABSTRACT TRUNCATED AT 400 WORDS)

History, 15th Century↗
PubMed2005

Vision and gaze direction modulate tactile processing in somatosensory cortex: evidence from event-related brain potentials.

Several behavioural studies have shown that directing one's gaze at a body part reduces detection speed and enhances discrimination of tactile stimuli at that location. We investigated how vision of a body part stimulated and manipulations of gaze direction affect tactile processing. Participants' gaze was directed to one of their hands, with vision of this hand either available or prevented in different experiments. They had to detect infrequent tactile targets among non-targets. Somatosensory event-related brain potentials were recorded in response to stimulation of the hand towards which gaze was directed (G+ trials) and in response to stimulation of the other hand (G- trials). When vision (V+) of the hand gaze was directed at was available (G+V+), an early positivity overlapping with the P45 and N 80 component was observed for G+V+ trials relative to G-V- trials. In contrast, when the hands were occluded from view (V-), an enhanced N 140 component followed by a late negativity was observed for G+V- as compared to G-V- trials. It is suggested that vision of the body part stimulated can modulate processing in primary somatosensory cortex (S1), while effects of gaze direction in the absence of vision of the body part touched are located in higher order somatosensory areas. Such effects of vision and gaze on tactile processing may be mediated by pathways from multimodal brain regions to somatosensory cortex.

Adult↗
PubMed2000

The effect of high-definition imaging on surgical task efficiency in minimally invasive surgery: an experimental comparison between three-dimensional imaging and direct vision through a stereoscopic TEM rectoscope.

BACKGROUND: In 1995, when we first used a high-definition television (HDTV) video system during a laparoscopic cholecystectomy in Tuebingen, we were surprised by the excellence of the spatial impression achieved by an image with improved resolution. Although any improvement in vision systems entails a trade-off among cost, quality, and complexity, high-definition imaging may well become an essential part of 3-D video systems. The aim of this experimental study was to assess the impact of high definition on surgical task efficiency in minimally invasive surgery and to determine whether it is preferable to use a 3-D system or a 2-D system with perfect resolution and color--for instance, HDTV or the three-chip charge-coupled device (3CCD). METHODS: We compared a 3-D video system with the vision through a stereoscopic rectoscope for transanal endoscopic microsurgery (TEM). Because its stereoscopic direct vision is not restricted to either shutter technology or video resolution, TEM optics represents the state of the art. For objective comparison, inanimate phantom models with suturing tasks were set up. The setups allowed the approach of parallel instruments as in TEM operations or via a laparoscopic approach, with oblique instruments coming laterally. Both types of procedure were carried out by highly experienced laparoscopic surgeons as well as those inexperienced in endoscopic surgery. These volunteers worked under 3-D video vision and/or TEM vision. Altogether, the model tasks were performed by 54 different persons. RESULTS: The evaluation did not show a significant (p > 0.05) difference in performance time in all models, but there was a clear trend showing the benefit of a higher resolution. CONCLUSION: We found a tendency for both endoscopically inexperienced and experienced surgeons to benefit from the use of a system with improved resolution (direct vision) rather than a 3-D shutter video system.

Efficiency↗
PubMed2002

Vision Disturbances Following Traumatic Brain Injury.

Vision disturbances following traumatic brain injury (TBI) include anomalies of accommodation, version, vergence (nonstrabismic, as well as strabismic), photosensitivity, visual field integrity, and ocular health. Traumatic brain injury patients with complex diplopia patterns, noncomitant strabismic anomalies, and advanced ocular health anomalies are either monitored by or referred to neuro-ophthalmologists and ophthalmologists for evaluation and possible surgical or medical intervention, as needed. Anomalies of accommodation, vergence, version, photosensitivity, and field of vision are amenable to noninvasive, rehabilitative interventions, such as vision therapy, which is rendered by optometrists and is described in this article. Further, vision therapy may be performed in isolation or in conjunction with the application of the following: Fusional prism spectacles (for diplopia) Tinted spectacles (for photosensitivity) Yoked prism spectacles (for visual-spatial hemispheric inattention, with or without a manifest visual field defect), as appropriate Dependent on the severity of vision impairment post-TBI, other types of rehabilitation, such as vestibular, physical, cognitive, and occupational rehabilitation, are deferred pending the stabilization of vision function to an appropriate level. Rehabilitative optometric intervention is appropriate and beneficial for many TBI patients. Therefore, it should be offered as a possible evaluation and treatment option to investigate the patient's symptoms and determine the prognosis for treatment, as would be done with any other therapeutic modality.

Journal Article↗
PubMed1996

The role of vision in repetitive circle drawing.

In the present experiment the role of vision in the control of repetitive circular movements was examined. Subjects drew circles at a 600 ms per circle rate. During the first nine seconds of the trial subjects moved with full vision and were paced by a metronome. During the latter 15 seconds, vision could be removed and/or the pacing signal could be removed. There were no effects of the pacing signal on the temporal and spatial characteristics of the circle. Withdrawal of vision did not affect the shape of the circle, but did change its scaler quality. The circles became smaller and the center drifted in a systematic fashion. Furthermore, the loss of vision produced an increase in variability in the circle shape, size and location. It is clear that in a simple task such as circle drawing, vision serves not as a source of information about form, but to maintain a stable and consistent form.

Adult↗
PubMedDate not supplied

The qualitative difference of visions and visual hallucinations: a comparison of a general-population and clinical sample.

Our objective was to analyze the frequency and quality of visions in a general-population sample compared with those experienced among schizophrenics. A sample group from the general population (n = 862) was compared with a group of schizophrenic patients (n = 19). Significant and qualitative differences were found in visions experienced by schizophrenic patients compared with subjects in the population sample. Women were more likely to experience visions of relatives than were men. The general population most commonly experienced visions of people, whereas schizophrenics were more likely to experience other phenomena. A qualitative difference thus exists in the type of visions experienced by schizophrenics compared with visions experienced by subjects from the general public.

Adult↗
PubMed1990

The contribution of vision to asymmetries in manual aiming.

An experiment was conducted to examine the hypothesis that the right hand system is superior in the processing of visual information. A manual aiming task utilizing four visual conditions was employed. In the full-vision (FV) condition subjects were afforded vision of both the hand and the target throughout the course of the movement. In the ambient-illumination-off (AO) condition, the room lights were extinguished at movement initiation, thus preventing vision of the moving limb. The target remained illuminated. In the target-off (TO) condition, the target was extinguished upon initiation of the movement. Ambient illumination and thus vision of the hand remained present. Finally there was a no-vision (NV) condition in which ambient illumination was removed and the target was extinguished upon initiation of the response movement. Although the manipulation of vision had potent effects upon terminal accuracy, and influenced reaction and movement time measures, the hands did not differ in the extent to which these characteristics were expressed. A left hand advantage for reaction time was observed. This may reflect a relative increase in right hemisphere involvement prior to aiming movements which are spatially complex.

Adult↗
PubMed1996

Residual vision with awareness in the field contralateral to a partial or complete functional hemispherectomy.

Two patients with unilateral disconnection or removal of the entire occipital lobe were tested for residual vision in their blind field. Using image stabilization to eliminate eye motion artifacts, the central portion of each subject's visual field was tested, beginning 1 degree from fixation and extending outward to 13.5 degrees. A narrow zone of residual vision was identified along the retinal vertical meridian of each patient. The lateral edge of this zone was generally within 3.5 degrees of the vertical meridian, though extended farther outward (but not beyond 6 degrees) at one field location for each subject. In one patient, it was present in both superior and inferior quadrants; in the other, it was confined to the superior quadrant. Within their zones of residual vision, both patients could detect stimuli and perform simple shape discriminations, but could not name complex line drawings. The patients were aware of their vision within this zone. No residual vision, with or without awareness, was found in areas tested outside these zones. Given the complete absence of visual cortex contralateral to the observed residual vision, alternate structures must be mediating these abilities.

Adolescent↗
PubMed1993

More than three different cone pigments among people with normal color vision.

A fundamental feature of normal color vision is that red and green lights can be mixed to appear identical with a monochromatic yellow light. Another characteristic of normal color vision is that people often disagree on the amounts of red and green needed in the mixture to exactly match the yellow. Comparison of such color vision differences with photopigment gene differences reveals that a serine/alanine polymorphism at amino acid position 180 of X-encoded pigments can account for this type of color vision variation. This amino acid change shifts the spectrum of the pigment produced by about 6 nm, a value that would predict a larger minimum color vision difference between individuals than is actually observed. This discrepancy can be explained if, counter to the Young-Helmholtz theory as the explanation of trichromacy, many people with normal color vision have more than three spectrally different cone pigments.

Base Sequence↗
PubMed2004

Color vision in epileptic adolescents treated with valproate and carbamazepine.

OBJECTIVE: The aims of our study were to evaluate whether deficits in color vision exist in epileptic adolescents, to study if monotherapy with valproic acid (VPA) and carbamazepine (CBZ) can affect color vision, and to determine the possible relationship between abnormal color vision tests and AEDs dosage and their serum concentrations. PATIENTS: We examined 45 epileptic patients before the beginning of therapy and after 1 year of VPA or CBZ monotherapy and 40 sex- and age-matched healthy controls. METHODS: Color vision was evaluated with Farnsworth Munsell 100 (FM100) hue test and achromatic and short-wavelength automated perimetry (SWAP). STATISTICAL ANALYSIS: To evaluate intergroup differences we used ANOVA with Scheffe's post hoc test, when appropriate. Repeated measures ANOVA was used to evaluate the intragroup modifications of total error score (TES) and perimetric threshold during the follow-up. Pearson's correlation test was performed to correlate chromatic sense and perimetric data and AEDs dosage and serum concentrations. RESULTS: Before the beginning of therapy, there were no differences in central color vision and SWAP between controls and epileptic patients. After 1 year, patients treated with VPA or CBZ showed a deficit in FM100 hue test and SWAP parameters while no significant deficit was found in achromatic perimetry. In particular, with the FM100 hue test a higher number of errors was found in both groups of patients (CBZ patients: 166.00 +/- 27.72 TES; VPA patients: 151.19 +/- 44.09, P < 0.001) in comparison with controls (controls: 109.29 +/- 24.73) and baseline values (CBZ patients: 110.65 +/- 22.9; VPA patients 107.43 +/- 21.70). With SWAP patients of both groups showed significant variation of foveal threshold (controls: 21.07 +/- 2.01 dB; CBZ patients: 19.35 +/- 1.32, P < 0.001; VPA patients: 18.88 +/- 1.89, P < 0.001), full-field mean threshold perimetric sensitivity (controls: 18.50 +/- 1.24 dB; CBZ patients: 16.60 +/- 1.47, P < 0.001; VPA patients: 16.23 +/- 1.55, P < 0.001) and mean threshold perimetric sensitivity of the three evaluated subareas of the visual field (area 1 controls: 21.01 +/- 1.15; CBZ patients: 19.45 +/- 1.74, P = 0.001; VPA patients: 18.25 +/- 1.61, P < 0.001; area 2 controls: 18.40 +/- 1.43; CBZ patients: 16.07 +/- 1.58, P +/- 0.001; VPA patients: 16.13 +/- 1.46, P = 0.001; area 3 controls: 17.20 +/- 1.49; CBZ patients: 14.28 +/- 1.51, P < 0.001; VPA patients: 14.31 +/- 2.90, P = 0.001). CONCLUSIONS: Our study demonstrates that treatment with VPA or CBZ can affect significantly both central and paracentral color vision after a short treatment period.

Adolescent↗