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PubMed1995

Jet pilot, helicopter pilot, and college student: a comparison of central vision.

Jet pilots (JP) (N = 44), helicopter pilots (HP) (N = 29), and college students (CS) (N = 41) were tested with a battery of vision tests designed to assess vision skills important for success as a naval aviator. Tests included measures of reaction time, high-contrast acuity, low-contrast acuity, spot detection, far-to-near gaze shift, near-to-far gaze shift, low-contrast acuity with glare, and dark focus. A Multi-Variate Analysis of Variance (MANOVA) compared the vision test performance of the three subject groups (JP, HP, and CS). Only with the Far-to-Near test was there no difference among the three groups. On all other tests, JP outperformed CS. The difference between HP and CS was less consistent and less dramatic than the difference between JP and CS. Only with the glare test were CS significantly better than HP. The results were interpreted as reflecting the influence of various selection factors, operational requirements, differential attrition, and age.

Adult↗
PubMedDate not supplied

[Seeing in the dark: limited vision in the aged as a prototypical "environmentally relevant" loss in competence].

In the conceptual part of this article, the existential dimension of experiencing a dramatic visual loss in late life is highlighted. Three theoretical avenues are proposed to approach age-related vision loss: 1) a stress and burden perspective; 2) a coping perspective, 3) an environmental psychology perspective. The empirical study is based on 84 elderly subjects suffering from vision loss (42 visually impaired, 42 blind), a comparison group of 42 subjects with mobility impairments, and a control group of 42 healthy subjects (particularly not impaired in vision or mobility). In all impaired groups, the impairment appeared after the age of 55 years; identification of subjects was based on medical expertise. Mean age varies between groups from 75 to 78 years with 30 females and 12 males in each group. Data based on person (e.g., ADL-functioning, subjective well-being, depressivity) as well as person-environment-transaction measures (e.g., microecology within the house, action range outside the house) were collected. Results revealed a reduced ADL-competence, lower subjective well-being, higher depressivity, and a shrinkage of action range in subjects suffering from visual loss. However, there was also a need for a differential perspective: For example, depending on person variables (living alone/not alone, degree of visual loss, coping style, coexisting illnesses), a different "resilience" against environmental pressure was observed. These findings point to the importance of a "differential" environmental gerontology.

Activities of Daily Living↗
PubMed1996

Fine grain of the neural representation of human spatial vision.

It is widely held that in human spatial vision the visual scene is initially processed through visual filters, each of which is responsive to narrow ranges of image spatial frequencies. The physiological basis of these filters are thought to be cortical neurons with receptive fields of different sizes. The grain of the neural representation of spatial vision is much finer than had been supposed. Using laser interferometry, which effectively bypasses the demodulation of the optics of the eye, we measured discrimination of, and adaptation to, high spatial frequency laser interference fringe patterns. Spatial frequency discrimination was good right up to the visual resolution limit (average Weber fractions of 0.13 at 50 c/deg). Both contrast and spatial frequency matches made after adapting to extremely fine interference fringes strongly suggested that there existed even finer, relatively unadapted, filters (mechanisms with small receptive fields). The smallest cortical receptive fields processing spatial information in human vision are so small that they can possess receptive field centers hardly wider than single cone photoreceptors.

Adaptation, Physiological↗
PubMed1996

Cross-modal correspondence between vision and olfaction: the color of smells.

Cross-modal sensory correspondences between vision and audition have been well described, but those between vision and olfaction have not. In Experiment 1, a method previously used to relate color names, mood names, and line elements was replicated and extended to describe odors by color. Significant color characterizations were found for all 20 test odors. Test-retest correlations showed color-odor correspondences to be as stable as nonodor measures after 2 years. In Experiment 2, new subjects matched Munsell color chips to the test odors. Thirteen odors had characteristic hues; there was significant variation in chroma and value. The selected Munsell hues corresponded to the color names endorsed in Experiment 1. Together, these experiments suggest the existence of robust correspondences between vision and olfaction.

Adolescent↗
PubMed1996

Motivational factors in vision therapy: comparison of computerized vs. manipulative techniques.

BACKGROUND: Vision therapy (VT) is a learning process that requires the patient to be motivated. Various modalities are used by practitioners to stimulate interest. This study compares the motivating effect of computers and manipulatives (i.e., physical objects that are handled). METHODS: Fifteen subjects were compared on three motivational standards: time on task, negative behaviors and patient choice of procedure; these standards were compared for two computerized VT procedures and two VT procedures using manipulatives. The visual abilities used for therapy were stereopsis and spatial visualization. RESULTS: Although both methods were motivating, the computerized techniques were clearly superior in all three measures for both visual abilities. CONCLUSIONS: Computerized vision therapy is an excellent modality for facilitating motivation for vision therapy.

Child↗
PubMed1996

Colour vision impairment in workers exposed to low concentrations of toluene.

Colour vision was examined by the Lanthony-D-15 desaturated test in 41 women exposed to toluene and in 29 non-exposed referents. Toluene exposure was evaluated by methods of environmental and biological monitoring. In the exposed group the median value of toluene in air was 35 ppm (range 11.2-49.9 ppm). Quantitative colour vision impairment was expressed as colour confusion index and colour confusion index corrected for alcohol intake. Qualitative impairment was expressed as normal, yellow-blue, red-green range or complex impairment. Statistical analysis showed the index values to be significantly correlated with age in both groups. In the exposed group they were significantly higher than in the non-exposed group. There was no significant difference in the prevalence of impairment in the blue-yellow range between the examined groups, although the prevalence of impairment in the exposed group was higher than in the non-exposed one. Results suggest that exposure to low toluene concentrations may induce colour vision impairment in women.

Adult↗
PubMed1998

Joslin Vision Network Validation Study: pilot image stabilization phase.

PURPOSE: This preliminary study is designed to evaluate the quality of initial images obtained using the Joslin Vision Network (JVN) image capture and retrieval system. METHODS: Digitized images of 18 patients (36 eyes) were obtained using Topcon Non-mydriatic Fundus Camera and various imaging protocols as described for each series of images. Level of retinopathy ranged from no diabetic retinopathy to proliferative diabetic retinopathy. Images were reviewed and evaluated in comparison to medical record notes and Early Treatment Diabetic Retinopathy Study (ETDRS) seven-standard field stereoscopic 35-mm retinal fundus photographs--when available--to determine the ability of JVN digitized images to allow appropriate diagnosis and clinical management. JVN images were also evaluated for presence of photographic artifacts and stereoscopic presentation. The various displays and relative value of each JVN display were also evaluated. RESULTS: Using combinations of JVN image displays, JVN images were shown to match diagnosed level of diabetic retinopathy as determined from record notes and/or ETDRS seven-standard field stereoscopic 35-mm retinal fundus photography. Viewing images with various combinations of JVN image displays delineates possible sources of artifacts in JVN images. Areas to guide future image capture and image reading are identified. CONCLUSIONS: The JVN image capture system and reading of images by certified readers should allow appropriate photodiagnostic information to support the JVN, the diabetes mellitus disease management telemedicine initiative of the Joslin Diabetes Center. A rigid, full-scale, masked study to compare the Joslin Vision Network to seven-standard field stereoscopic 35-mm retinal fundus photography should be pursued to validate the image-gathering and image-reading strategy to support the Joslin Vision Network.

Adult↗
PubMed1991

Velhagen Pfügertrident pseudoisochromatic plates in screening congenital red-green vision defects.

Red-green colour vision defects were screened in a group of 425 trade school students using Velhagen Pflügertrident pseudoisochromatic plates. Thereafter, the students were examined with the Nagel anomaloscope. Of the 425 students, 31 (7.3%) were found to be colour defectives. Deuteranomalous defects were found in 4.9% of cases; deuteranopic defects, in 0.2%; and protanomalous defects, in 2.1%. There were no protanopic students in the study group. The Velhagen plates found 19 of the 31 defectives (sensitivity, 61.3%); none of the students with normal colour vision were suspected of being colour defectives (specificity, 100%). The sensitivity of the Velhagen plates is not as high as that of other pseudoisochromatic tests. However, the Velhagen Pflügertrident test is easy to use when screening of pre-school-aged children is needed.

Adolescent↗
PubMed1990

Architecture and design of a computerised stereogram generator for vision test.

A new microcomputer-based stereogram generator was designed and implemented to generate various visual stimuli that are used for testing the binocular vision system. The system is capable of generating static and dynamic stereoscopic stereograms that can be varied in size, shape, speed and disparity. It can also be used to generate a luminous stimulus on a dark background which, except for the depth parameters, can be varied in a similar way to the stereoscopic stimulus. A 16/32-bit microprocessor has been employed for the overall control of the stereogram parameters, which provides flexibility, versatility, compactness and speed at reduced cost. We have applied this system to the measurement of eye movement and computer vision.

Diagnosis, Computer-Assisted↗
PubMed2005

Advantages of binocular vision for the control of reaching and grasping.

Theoretical considerations suggest that binocular information should provide advantages, compared to monocular viewing, for the planning and execution of natural reaching and grasping actions, but empirical support for this is quite equivocal. We have examined these predictions on a simple prehension task in which normal subjects reached, grasped and lifted isolated cylindrical household objects (two sizes, four locations) in a well-lit environment, using binocular vision or with one eye occluded. Various kinematic measures reflecting the programming and on-line control of the movements were quantified, in combination with analyses of different types of error occurring in the velocity, spatial path and grip aperture profiles of each trial. There was little consistent effect of viewing condition on the early phase of the reach, up to and including the peak deceleration, but all other aspects of performance were superior under binocular control. Subjects adopted a cautious approach when binocular information was unavailable: they extended the end phase of the reach and pre-shaped their hand with a wider grip aperture further away from the object. Despite these precautions, initial grip application was poorly coordinated with target contact and was inaccurately scaled to the objects' dimensions, with the subsequent post-contact phase of the grasp significantly more prolonged, error-prone and variable compared to binocular performance. These effects were obtained in two separate experiments in which the participants' performed the task under randomized or more predictable (blocked) viewing conditions. Our data suggest that binocular vision offers particular advantages for controlling the terminal reach and the grasp. We argue that these benefits derive from binocular disparity processing linked to changes in relative hand-target distance, and that this depth information is independently used to regulate the progress of the approaching hand and to guide the digits to the (pre-selected) contact points on the object, thereby ensuring that the grip is securely applied.

Adult↗
PubMed1996

Vision outcome at age 2 years in a low birth weight population.

We assess the prevalence of vision problems in a cohort of low birth weight infants at age 2 years and the relationship of these problems to neonatal brain injury. Data on prenatal and neonatal history and brain injury status were prospectively collected on 721 children weighing 500-2,000 gm at birth enrolled in a multi-center, population-based longitudinal study. Visual acuity was evaluated using the Teller Acuity Card Procedure. Abnormalities of the eye were assessed by a specially trained pediatric nurse practitioner. Failure of the acuity screen occurred in 62 of 699 tested (8.9%). Multiple logistic regression analysis revealed that the only significant independent predictors of failure included presence of disabling cerebral palsy (DCP) (odds ratio [OR] = 14.8) or nondisabling cerebral palsy (NDCP) (OR = 4.0) and Apgar score of less than 5 at 5 minutes (OR = 2.4). Parenchymal brain injury (PEL) was of borderline significance. Strabismus was present in 123 of 702 children (17.5%). Multiple logistic regression analysis disclosed that the joint predictors of strabismus were presence of DCP (OR = 7.2) and length of hospital stay (OR = 1.6). We conclude that low birth weight infants with parenchymal brain lesions leading to cerebral palsy are at particular risk for vision problems early in life and should be carefully evaluated.

Brain Injuries↗
PubMed2005

Vision abnormalities in young children exposed prenatally to organic solvents.

Despite an accumulating body of evidence demonstrating that the visual system is an important target for organic solvent toxicity in adults, little attention has been paid to the visual functioning of children with prenatal exposure to organic solvents. The present study aimed to: (1) determine prospectively whether prenatal solvent exposure increases the risk of visual deficits in infants and (2) assess the relationship between estimates of exposure level and integrity of visual responses. A sample of 21 infants born to women who were occupationally exposed to solvents during pregnancy was compared with 27 non-exposed age-matched control infants. All mothers were recruited from Motherisk, an antenatal counseling service in Toronto, Canada. Contrast sensitivity and grating acuity were assessed using a sweep visual evoked potential (VEP) technique whereas chromatic- and achromatic mechanisms were assessed using a transient VEP technique. Exposure level was estimated from questionnaire data obtained during pregnancy. Testers were masked to exposure status. Results showed a significant reduction in contrast sensitivity in the low and intermediate spatial frequency range in solvent-exposed infants compared to controls (p<0.001). With respect to grating acuity, there was a significant effect of exposure level, with children in the high exposed having reduced grating acuity compared with children in the low exposed group (p<0.025) and controls (p=0.02). Regarding color vision, 26.3% of infants in the exposed group versus 0% of the controls produced abnormal VEP responses to the red-green onset stimulus (p<0.01), but not to either blue-yellow or achromatic stimuli. No differences were found with respect to latency or amplitude of chromatic and achromatic response. These findings suggest that prenatal solvent exposure is associated with selective visual deficits, including reduced contrast sensitivity and abnormal red-green vision. Increasing levels of exposure may lead to further visual deficits affecting grating acuity. These findings support the need for a re-evaluation of current occupational exposure standards for pregnant women.

Adult↗
PubMed2005

A nationwide population-based survey on visual acuity, near vision, and self-reported visual function in the adult population in Finland.

PURPOSE: To estimate the prevalence rates of habitual visual acuity (VA) levels and visual impairment in Finland and to assess their correlation with self-reported visual function. DESIGN: Cross-sectional population-based study. PARTICIPANTS: Subjects were selected randomly from the Finnish population aged 30 years or older. Of 7979 eligible people, 7393 (93%) were interviewed, 6771 (85%) were examined, and 6663 (84%) had distance VA assessed. METHODS: Participants underwent a home interview and a comprehensive examination including measuring binocular VA for distance and for near with the participants' current spectacles, if any. MAIN OUTCOME MEASURES: The level of VA for distance and for near with current spectacle correction. The self-reported capability to read newsprint and television text and the ability to move about without being restricted by reduced vision. RESULTS: The prevalence of good to moderate VA for distance (VA> or =0.5 [> or =20/40]) measured with current spectacles was 95.9%, and 87.4% had a VA level of 0.8 (20/25) or better. The prevalence of habitual visual impairment (VA< or =0.25 [< or =20/80]) was 1.6%, and 0.5% were blind (VA<0.1 [<20/200]). The prevalence of visual impairment increased significantly with age (P<0.001), especially in the age group of 65 to 74 years and upward. There was no gender difference in VA for distance, but decreased near vision (VA< or =0.25 [< or =20/80]) was significantly more common in men than in women (P<0.01). By applying the imputated numbers of visually impaired and blind participants to the Finnish population (approximately 3 million aged 30 years or older), there were approximately 65000 (2.1%) visually impaired and 17000 (0.6%) blind adult persons in the country in 2000. The correlation between self-reported visual ability and measured visual function was moderate but statistically significant (r = 0.27-0.40; P<0.0001). The proportion of people with reading difficulties or who were unable to read newsprint has decreased 7% during the last 2 decades. CONCLUSIONS: Functional visual impairment increased with age especially in the age group of 65 to 74 years and upward and was as prevalent in women as in men. The prevalence of people with reading difficulties has decreased considerably since 1980.

Adult↗
PubMed2006

Posterior sub-Tenon's capsule injection of triamcinolone acetonide prevents panretinal photocoagulation-induced visual dysfunction in patients with severe diabetic retinopathy and good vision.

PURPOSE: To evaluate prospectively the efficacy of a single sub-Tenon's capsule injection of triamcinolone acetonide (TA) against panretinal photocoagulation (PRP)-induced macular thickening and visual disturbance in patients with severe diabetic retinopathy and good vision. DESIGN: Prospective, comparative, interventional case series. PARTICIPANTS: Twenty eyes of 10 patients with severe nonproliferative diabetic retinopathy or non-high-risk proliferative diabetic retinopathy whose visual acuity was 20/40 or better (<0.3 in logarithm of the minimum angle of resolution [logMAR] acuity) before the PRP, whose retinopathy was bilateral and symmetrical. The averaged parafoveal retinal thickness was more than 300 microm, leading to a worse visual prognosis after PRP. INTERVENTION: Sub-Tenon's capsule injection of 20 mg TA. MAIN OUTCOME MEASURES: Best-corrected visual acuity (BCVA) with logMAR chart and averaged foveal thickness (FT) using the retinal mapping program of optical coherence tomography. METHODS: In all patients, PRP was performed every other week for 4 sessions on both eyes, and 1 week before PRP; 1 eye received the TA injection, and the other eye served as a control. The clinical course of BCVA and FT was monitored for up to 24 weeks after beginning PRP. RESULTS: Before TA injection, BCVA and FT were 0.055+/-0.072 and 235.5+/-37.5 microm in the TA-injected eye and 0.065+/-0.071 and 233.7+/-39.8 microm in the control eye, respectively; there was no significant difference between eyes. After the TA injection, FT in the TA-injected eyes was significantly decreased. During and after the PRP, FT in the control eye increased dramatically and reached 312.0+/-68.2 microm at 24 weeks, which was significantly different from that in the TA-injected eyes (235.3+/-38.6 microm at 24 weeks). Best-corrected visual acuity in the control eye decreased with time to 0.24+/-0.13; in contrast, and BCVA in the TA-injected eye was good (to 0.085+/-0.11) . CONCLUSIONS: As a pretreatment for PRP, a single sub-Tenon's capsule injection of TA has beneficial effects for preventing PRP-induced foveal thickening and visual dysfunction in patients with severe diabetic retinopathy and good vision.

Aged↗
PubMed2006

Enhanced visual experiences and seeing hardware for reduced vision: a pilot study.

BACKGROUND: Persons with vision loss may have limited ability to experience visual arts and difficulty navigating unfamiliar environments. The Center for Advanced Visual Studies at Massachusetts Institute of Technology developed a Retinal Imaging Machine Vision System (RIMVS) "seeing machine" to project "word-images" onto the retina and permit navigation through virtual architectural environments. METHODS: Ten subjects with visual acuity < or = 20/70 in the better-seeing eye were recruited. Subjects viewed word-images that were projected on the retina of the better-seeing eye and asked to interpret the images. Subsequently, they were asked to recall as many images as possible. Participants also practiced navigation through a computer-modeled building that was projected onto the retina. A survey elicited subject response to the RIMVS. RESULTS: Six subjects correctly interpreted all 10 word-images; no subject interpreted fewer than 8 correctly. Seven subjects felt that the word images afforded easy recall, and 7 subjects responded that the technology might assist subsequent navigation in unfamiliar environments. CONCLUSIONS: Responses reflect a general interest and potential with the RIMVS. Further studies are warranted to explore the value of the RIMVS as a tool to enable visually compromised persons to experience and appreciate visual arts and as a navigation aid.

Adult↗
PubMed1992

The Tokyo Metropolitan Home Vision Screening Program for amblyopia in 3-year-old children.

In August 1989, the Tokyo Metropolitan Government officially began a vision screening program for children aged 3 years 1 month. A 1988 pilot study of 1,303 children this age disclosed five cases (0.38%) of amblyopia. The home vision test, which uses picture cards of familiar figures, proved to be an efficient and inexpensive method of screening when incorporated into the existing health-check program for 3-year-old children. In the initial eight months of the program, 21,906 children were screened. Of these, 419 children (1.9%) were referred to an ophthalmologist for follow-up, and amblyopia was detected in 41 children (0.19%).

Amblyopia↗
PubMed1995

Assessment of vision and visual attention in minimally responsive brain injured patients.

Sensory, motor, and cognitive assessment is a critical priority in the care of minimally responsive brain-injured patients. However, their inconsistent pattern of responding may interfere with the use of traditional forms of assessment such as the mental status or neurological examinations. In this article we describe a quantitative method, based on single-subject experimental design, for evaluating vision and visual attention in this patient population. In a series of randomized trials, combinations of a blank card, a colorful photograph, and no stimulus are presented to either or both visual fields while horizontal eye movements are observed. The relationship between the side and nature of the visual stimulus and the frequency of eye movements is analyzed to determine visual function in one or both eyes. We report six cases of minimally responsive patients assessed with this method. In case A, we show evidence of functional vision in both visual fields. Case B also shows functional fields, but with a monocular visual deficit. Cases C and D show a homonymous hemianopsia which, in case D, is further complicated by a monocular visual deficit. Finally, cases E and F show patterns of left and right visual extinction. Thus, this objective and quantitative method leads to conclusions about patients' visual function that are not readily apparent by clinical observation and that allow appropriate modifications in further assessment or treatment.

Adolescent↗
PubMed2000

Vision standards for driving in Canada and the United States. A review for the Canadian Ophthalmological Society.

We review the vision requirements for driving with the goal of revising current Canadian Ophthalmological Society (COS) recommendations for vision standards for driving. The report comprises two sections. In the first section we report the results of a survey of transportation authorities in Canada and the United States conducted on behalf of the COS to determine the current standards and medical review procedures. The results suggest that although the standards in Canada are more consistent than those in the United States, few of the standards in either country are evidence-based. In the second section we review the recent literature on visual function and driving. We conclude from this review that adequate contrast sensitivity is as important as, if not more important than, good visual acuity for driving and that there is little evidence to support a monocular standard for acuity, contrast sensitivity or visual field. Although there is evidence that the extent of a visual field defect is related to the ability to perform driving tasks, there is little evidence to suggest a relation between the location of the visual field defect and fitness to drive.

Automobile Driving↗