Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “VISION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22Linked to original sources
PubMed2002

The validity of the University of Waterloo Colored Dot Test for Color Vision Testing in adults and preschool children.

PURPOSE: Most color vision tests require a high level of cognitive ability and as such are problematic for preschool children and multiply challenged individuals. Our goal was to design a color vision test for these groups and evaluate the clinical utility for preschool children. METHODS: The University of Waterloo Colored Dot Test (UWCDot) for Color Vision Testing requires the subject to distinguish a colored disc from seven gray discs. The target disc was a Munsell color along the deutan, protan, or tritan confusion line with gray. The first phase estimated the sensitivity and specificity of the test for adults. Thirty-one adults with normal color vision and 21 adults with congenital red-green defects participated. In the second phase, the utility of the UWCDot test for screening preschool children was determined. Subjects were 281 males and 269 females aged 2.5 to 5 years with normal vision. Their color vision was also assessed with the Standard Pseudoisochromatic Plates, Part 1 (SPP1). RESULTS: The sensitivity and specificity of UWCDot for adults approached the values for the desaturated D-15 when subjective responses were scored. Monitoring fixational eye movements produced sensitivity and specificity values that were similar to the anomaloscope. After adjusting the scoring criterion for the preschool children by using the females as a control, 2.9% of the males were identified as red-green deficient, 1.8% were blue-yellow deficient, and 3.2% had an unclassified deficiency. By definition, 1% of the females failed the test. Counting fixational eye movements was not a useful scoring method in the preschool children. Comparisons with SPP1 indicated that the UWCDot uncovers approximately 35% of the individuals with definite red-green color vision defects. CONCLUSIONS: Our results indicate that the UWCDot is capable of detecting approximately 35% of the preschool children who have a congenital red-green color vision defect. These individuals are likely to have a more severe deficiency.

Adult↗
PubMed2006

Capturing the benefit of vision restoration therapy.

PURPOSE OF REVIEW: Vision restoration therapy has shown promise as a treatment strategy to improve visual field deficits in patients with lesions of the brain or optic nerve. Objective measures of its efficacy, however, have remained controversial. A review of the current theories supporting the reported benefits of vision restoration therapy, and the dissenting opinions, reconsiders vision restoration therapy as an emerging therapy. RECENT FINDINGS: The benefits of vision restoration therapy have been challenged by a study suggesting that no improvement exists with careful control of fixation. Alternatively, others suggest that eye movements are not induced by vision restoration therapy. Functional imaging studies demonstrate the potential role of plasticity in vision restoration therapy. While the exact mechanism remains to be elucidated, subjective improvement in daily functioning is reported in a significant percentage of patients. SUMMARY: Vision restoration therapy is a noninvasive, home-based strategy for the rehabilitation of patients with visual field loss caused by structural or ischemic damage. While subjective benefits in functional status have been reported by patients following completion of the program, debate centers around the inadequacy of the methods used to document its efficacy. Until such a method is validated by carefully controlled studies, subjective improvement in visual function stands alone as evidence of vision restoration therapy's benefit.

Hemianopsia↗
PubMed1996

The practical use of vision in small teams.

Sets out to demonstrate the usefulness of vision statements to self-directed work teams, taking ideas from the development of vision within teams in an organization of around 1,000 employees. Considers barriers to the creation of a shared vision in which employees have a stake, putting forward the concept of ¿team-sized vision¿ as a means of coping with the identified problems of ¿size¿ and ¿ownership¿ with regard to organization-sized vision. Outlines various advantages of team-sized vision, e.g. enabling positive discussion of change and acting as a strong motivator. Sets out a process for the generation of team-sized vision, broken down into four main steps. Concludes that the process can be undertaken with relative ease and that vision is for all levels of the organization--not just top management.

Group Processes↗
PubMedDate not supplied

Profile of a low vision clinic population.

BACKGROUND: Causes of low vision and types of low vision devices (LVDs) prescribed in other low vision clinics have been studied extensively. Similar studies have not been conducted in Malaysia. This paper reports the results of a retrospective study of 573 patients seen at the Universiti Kebangsaan Malaysia-Malaysian Association for the Blind (UKM-MAB) low vision clinic in Kuala Lumpur. METHODS: The record cards of 573 patients seen at the UKM-MAB clinic over 10 years were examined and the following information extracted: date of first consultation, age, sex, cause of visual impairment as diagnosed by an ophthalmologist and types of low vision devices (LVDs) prescribed. RESULTS: The majority of patients were from the younger age groups with 423 (73.8 per cent) less than 50 years of age. Three hundred and ninety-five (68.9 per cent) of the subjects were males and 178 (31.1 per cent) female. The main causes of low vision were congenital structural defects including nystagmus among patients in the zero to 29 years age group, retinitis pigmentosa among the 30 to 59 years age group and age-related macular degeneration (ARM) among those over 60 years of age. CONCLUSIONS: Since the majority of the patients were from the younger age group the main causes of low vision were congenital and hereditary diseases. Three hundred and forty-one (59.5 per cent) patients seen at the low vision clinic accepted the use of LVDs.

Journal Article↗
PubMed2001

Reading performance in children with low vision.

PURPOSE: While educators and optometrists are concerned with reading efficiency in children with low vision, in most low vision assessments, children's reading performance is assessed only by a brief evaluation of reading fluency. We examined the relationships between clinical vision measures and reading performance in children with low vision. METHODS: Subjects were 71 students with low vision, aged seven to 18 years. The vision and reading performance measures were: high contrast distance visual acuity, contrast sensitivity using both the Pelli-Robson and LH symbol charts, near text visual acuity and reading rates on a range of print sizes. RESULTS: Most children achieved maximum reading rate at print sizes between 2.5 and seven times larger than threshold print size. Maximum reading rate increased significantly with age and near visual acuity. There was no significant relationship between reading rate and contrast sensitivity. CONCLUSIONS: The majority of children with low vision can achieve near normal reading rates with magnification. Age is the strongest predictor of reading rate in children with low vision. They need print sizes well above threshold to achieve maximum reading rate. Routine contrast sensitivity testing of visually impaired students is not indicated for reading assessment.

Journal Article↗
PubMed1976

Extreme vestibulo-ocular adaptation induced by prolonged optical reversal of vision.

1. These experiments investigated plastic changes in the vestibulo-ocular reflex (VOR) of human subjects consequent to long-term optical reversal of vision during free head movement. Horizontal vision-reversal was produced by head-mounted dove prisms. Four normal adults were continuously exposed to these conditions during 2, 6, 7 and 27 days respectively.2. A sinusoidal rotational stimulus, previously shown to be nonhabituating (1/6 Hz; 60 degrees /sec amplitude), was used to test the VOR in the dark at frequent intervals both during the period of vision-reversal and an equal period after return to normal vision. D.c. electro-oculography (EOG) was used to record eye movement, taking care to avoid changes of EOG gain due to light/dark adaptation of the retina.3. All subjects showed substantial reduction of VOR gain (eye velocity/head velocity) during the first 2 days of vision-reversal. The 6-, 7- and 27-day subjects showed further reduction of gain which reached a low plateau at about 25% the normal value by the end of one week. At this time the attenuation of some EOG records was so marked as to defy extraction of a meaningful sinusoidal signal.4. After removal of the prisms VOR gain recovered along a time course which approximated that of the original adaptive attenuation.5. In the 27-day experiment large changes of phase developed in the VOR during the second week of vision-reversal. These changes generally progressed in a lagging sense, to reach 130 degrees phase lag relative to normal by the beginning of the third week. Accompanying this was a considerable restoration of gain from 25 to 50% the normal value. These adapted conditions, which approximate functional reversal of the reflex, were then maintained steady, even overnight, until return to normal vision on the 28th day.6. Thereafter, whereas VOR phase returned to near-normal in 2 hr, restoration of gain occupied a further 2-3 weeks.7. There was a highly systematic relation between instantaneous gain and phase, even during periods of widely fluctuating change associated with transition from one steady state to another. During such transition there was a tendency for directional preponderance to occur in the VOR.8. All the observed changes were highly specific to the plane of vision-reversal, no VOR changes being observed in the sagittal plane.9. VOR changes were adaptive, in the sense that they were always goal-directed towards the requirements of retinal image stabilization during head movement. They were plastic to the extent that there was extensive and retained remodelling of the reflex towards this goal.10. It is inferred that all the observed changes in gain and phase are compatible with a simple neural network employing known vestibulo-ocular projections via brainstem and cerebellar pathways, providing that the reversed visual tracking task can produce plastic modulation of efficacy in the cerebellar pathway and that this pathway exhibits a dynamic characteristic producing moderate phase lead in a sinusoidal signal at 1/6 Hz.

Journal Article↗
PubMed2005

Impact of unilateral and bilateral vision loss on quality of life.

AIM: To investigate whether unilateral vision loss reduced any aspects of quality of life in comparison with normal vision and to compare its impact with that of bilateral vision loss. METHODS: This study used cluster stratified random sample of 3271 urban participants recruited between 1992 and 1994 for the Melbourne Visual Impairment Project. All predictors and outcomes were from the 5 year follow up examinations conducted in 1997-9. RESULTS: There were 2530 participants who attended the follow up survey and had measurement of presenting visual acuity. Both unilateral and bilateral vision loss were significantly associated with increased odds of having problems in visual functions including reading the telephone book, newspaper, watching television, and seeing faces. Non-correctable by refraction unilateral vision loss increased the odds of falling when away from home (OR = 2.86, 95% CI 1.16 to 7.08), getting help with chores (OR = 3.09, 95% CI 1.40 to 6.83), and becoming dependent (getting help with meals and chores) (OR = 7.50, 95% CI 1.97 to 28.6). Non-correctable bilateral visual loss was associated with many activities of daily living except falling. CONCLUSIONS: Non-correctable unilateral vision loss was associated with issues of safety and independent living while non-correctable bilateral vision loss was associated with nursing home placement, emotional wellbeing, use of community services, and activities of daily living. Correctable or treatable vision loss should be detected and attended to.

Accidental Falls↗
PubMed2004

Comparative effects of pH and Vision herbicide on two life stages of four anuran amphibian species.

Vision, a glyphosate-based herbicide containing a 15% (weight:weight) polyethoxylated tallow amine surfactant blend, and the concurrent factor of pH were tested to determine their interactive effects on early life-stage anurans. Ninety-six-hour laboratory static renewal studies, using the embryonic and larval life stages (Gosner 25) of Rana clamitans, R. pipiens, Bufo americanus, and Xenopus laevis, were performed under a central composite rotatable design. Mortality and the prevalence of malformations were modeled using generalized linear models with a profile deviance approach for obtaining confidence intervals. There was a significant (p < 0.05) interaction of pH with Vision concentration in all eight models, such that the toxicity of Vision was amplified by elevated pH. The surfactant is the major toxic component of Vision and is hypothesized, in this study, to be the source of the pH interaction. Larvae of B. americanus and R. clamitans were 1.5 to 3.8 times more sensitive than their corresponding embryos, whereas X. laevis and R. pipiens larvae were 6.8 to 8.9 times more sensitive. At pH values above 7.5, the Vision concentrations expected to kill 50% of the test larvae in 96-h (96-h lethal concentration [LC50]) were predicted to be below the expected environmental concentration (EEC) as calculated by Canadian regulatory authorities. The EEC value represents a worst-case scenario for aerial Vision application and is calculated assuming an application of the maximum label rate (2.1 kg acid equivalents [a.e.]/ha) into a pond 15 cm in depth. The EEC of 1.4 mg a.e./L (4.5 mg/L Vision) was not exceeded by 96-h LC50 values for the embryo test. The larvae of the four species were comparable in sensitivity. Field studies should be completed using the more sensitive larval life stage to test for Vision toxicity at actual environmental concentrations.

Animals↗
PubMedDate not supplied

The vision trap.

At Mentor Graphics Corporation, Gerry Langeler was the executive responsible for vision, and vision, he discovered, has the power to weaken a strong company. Mentor helped to invent design-automation electronics in the early 1980s, and by the end of the decade, it dominated the industry. In its early days, fighting to survive, Mentor's motto was Build Something People Will Buy. Then when clear competition emerged in the form of Daisy Systems, a startup that initially outsold Mentor, the watchword became Beat Daisy. Both "visions" were pragmatic and immediate. They gave Mentor a sense of purpose as it developed its products and gathered momentum. Once Daisy was beaten, however, company vision began to self-inflate. As Mentor grew more and more successful, Langeler formulated vision statements that were more and more ambitious, grand, and inspirational. The company traded its gritty determination to survive for a dream of future glory. The once explicit call for effective action became a fervid cry for abstract perfection. The first step was Six Boxes, a transitional vision that combined goals for success in six business areas with grandiose plans to compete with IBM at the level of billion-dollar revenues. From there, vision stepped up to the 10X Imperative, a quality-improvement program that focused on arbitrary goals and measures that were, in fact, beyond the company's control. The last escalation came when Mentor Graphics decided to Change the Way the World Designs. The company had stopped making product and was making poetry. Finally, in 1991, after six years of increasing self-infatuation, Mentor hit a wall of decreasing indicators. Langeler, who had long since begun to doubt the value of abstract visions, reinstated Build Something People Will Buy. And Mentor was back to basics, a sense of purpose back to its workplace.

Decision Making, Organizational↗
PubMed1999

Restoration of vision I: neurobiological mechanisms of restoration and plasticity after brain damage - a review.

Lesions in the central nervous system often lead to loss of vision due to visual system involvement. In the course of weeks or months, some vision can recover in rats, cats, monkeys, and humans, though it is mostly incomplete. This paper reviews the current knowledge of the under-lying neurobiological mechanism of recovery of vision, particularly those observed in adult rats with partial optic nerve crush (ONC). Immediately after ONC, rats are almost completely blind, evident by their inability to perform visual tasks such as brightness and pattern discrimination and they fail to orient towards small, moving targets. Within about two weeks, however, rats significantly recover some of their lost visual functions despite the fact that only about 10 % of the retinal ganglion cells (RGCs) maintain a viable connection with their brain tar-gets. Molecular, anatomical and physiological studies have identified some of the neurobiological determinants of this visual restitution. Immediately following ONC there is a massive soma swelling of about 80 % of the RGCs with subsequent cell death due to apoptosis and necrosis. The remaining 20 % survive with or without axonal connection to their target and undergo marked changes: (i) about half of these RGCs experience a moderate, reversible soma swelling, (ii) there is a loss of anterograde axonal transport in the optic nerve which partially recovers after several weeks, and (iii) many of the surviving RGCs undergo alterations in gene expression, particularly that of the NR1 receptor and the immediate early gene, c-jun. While these changes may be part of an adaptive program of the cells to cope with the trauma, cell survival in the retina does not correlate well with subsequent recovery of vision. We have therefore also studied plasticity in the down stream denervated brain structures which are innervated by retinofugal pathways, particularly the superior colliculus. Here we found (i) recovery of metabolic activity and (ii) changes in gene expression, such as an up-regulation of the enhancer of split (R esp-1) gene. When viewed together with studies on recovery of vision and neuronal reorganization done in other laboratories it is clear that recovery of vision involves simultaneous plasticity in the damaged structure itself and, transsynaptically, in down-stream structures such as the tectum, the lateral geniculate nucleus and visual cortex. Considering both pre-clinical and clinical evidence, I propose the biological substrate underlying restoration of vision as follows: surviving neurons within areas of partial damage - which corresponds clinically to "transition zones" located between intact and deficient visual field sectors - act in concert with down-stream areas, which themselves undergo dramatic reorganization to cope with a condition of reduced, but residual input. Restitution of vision is therefore a multifactorial event of within-systems plasticity, involving neurobiological alterations along the entire retinofugal axis. It is likely that these mechanisms are also responsible for visual improvements that are seen both in animals and patients after prolonged visual restitution training.

Journal Article↗
PubMed2006

Contrast sensitivity and color vision in HIV-infected individuals without infectious retinopathy.

PURPOSE: To investigate the relationship between abnormal contrast sensitivity and abnormal color vision among human immunodeficiency virus (HIV)-infected individuals who have normal visual acuity and to seek host factors that predict these abnormalities. DESIGN: Noninterventional, cross-sectional study. METHODS: We evaluated 71 HIV-infected subjects with visual acuity of 20/25 or better, clear media, and no vision-threatening retinal lesions. Visual function was determined using the Pelli-Robson contrast sensitivity test and the Farnsworth-Munsell 100-Hue color test (FM-100). Results were compared with published values for normal populations and to measures of HIV disease severity. We evaluated two levels of impairment for each visual function. "Mild dysfunction" was defined as > or =1 standard deviation (SD), but <2 SD from normal means. "Abnormal" was defined as > or =2 SD from normal means. RESULTS: The prevalences of abnormal contrast sensitivity and abnormal color vision were 7.0% and 9.9%, respectively. We did not identify relationships between impaired contrast sensitivity and impaired color vision. Impaired color vision was associated with increasing age (r = 0.36, P = .002). We could not identify significant correlations between either contrast sensitivity or color vision values and the following factors: current or nadir (lowest previous) CD4+ T-lymphocyte count, HIV blood level, and Karnofsky score. CONCLUSIONS: Abnormal contrast sensitivity and abnormal color vision can occur independently in HIV-infected individuals and can be present in the absence of severe immunosuppression.

Adult↗
PubMed2004

Low contrast vision function predicts subsequent acuity loss in an aged population: the SKI study.

Can vision tests predict subsequent loss of acuity? The association between performance on several low contrast spatial vision measures, glare recovery, color discrimination, flicker sensitivity, stereopsis and ocular disease status at baseline and acuity loss 4.4 years later was examined in a large aged random sample with good initial acuity. In univariate analyses, several vision measures, retinal disease status and age were each significant predictors of subsequent acuity loss. In a multiple regression analysis, only low contrast spatial vision was a significant predictor, but the other vision measures, retinal disease status and age were not. For each doubling of low contrast spatial vision threshold at baseline, individuals were more than two times as likely to suffer subsequent significant visual acuity loss. Tests of low contrast spatial vision are strong predictors of significant subsequent visual acuity loss. These findings have implications for clinical trials, clinical management, and acceptance of these measures into clinical practice.

Aged↗
PubMed2003

Color vision impairment in workers exposed to neurotoxic chemicals.

Recent research shows that occupational exposure to several solvents, metals and other industrial chemicals can impair color vision in exposed workers. Occupation-related color vision impairment usually results in blue-yellow color discrimination loss or, less frequently, a combination of blue-yellow and red-green loss. The eyes may be unequally involved, and the course is variable depending on exposure and other factors. The pathogenesis of occupational color vision loss has not been elucidated; it may be due to, e.g. a direct action of neurotoxins on receptors, possibly on the cone's membrane metabolism, and/or to an interference with neurotransmitters within the retina. Other possible pathogenetic mechanisms, such as a direct effect to the optic nerve, have also been suggested. Occupational color vision loss is usually sub-clinical, and workers are unaware of any deficit. It can be assessed using sensitive tests, such as the Farnsworth-Munsell 100 Hue (FM-100) or the Lanthony D-15 desaturated panel (D-15 d). The latter is the most widely used for studies in groups of exposed workers, and offers the possibility of a quantitative evaluation of the results by calculation of the Bowman's Color Confusion Index (CCI), or of the Vingrys' and King Smith's Confusion Index (CI). Other advantages of D-15 d are the possibility to perform the test directly at the workplace, and the reproducibility when performed in standardized conditions. In most cases, occupation-related color vision impairment is correlated to exposure levels, and has often been observed in workers exposed to environmental concentrations below the current occupational limit proposed by the ACGIH. Progression with increasing cumulative exposure has been reported, while reversibility is still discussed. Acquired color vision impairment related to occupational exposure to styrene, perchloroethylene (PCE), toluene, carbon disulfide, n-hexane, solvent mixtures, mercury and some other chemicals are discussed. Results show that color vision testing should be included in the evaluation of early neurotoxicity of chemicals in exposed workers. The D-15 d would be useful in the surveillance of workers exposed to solvents and other chemicals toxic to the visual system.

Animals↗
PubMed2003

Practical assessment of vision in the elderly.

In this article we have demonstrated the significant visual impairments in elders with good vision by standard measures when the viewing conditions are less than ideal--low contrast, low or changing light level, or glare. Much of this impairment can be accounted for by the known age-related changes in the eye. We have emphasized that two people of the same age with the same standard acuity can have dramatically different vision under these nonideal conditions. Because one cannot predict vision under these conditions on the basis of standard acuity, it is important to use these additional measures. These other vision measures are more closely related to task performance (reading, face recognition) than standard acuity. We find that persons who perform poorly on these low-contrast measures are more likely to have significant losses of standard acuity in the future. Hence, these measures help identify persons who should be more closely monitored. Each of the vision functions shows significant decline across age. It is important to recognize that a 60-year-old with 20/30 acuity is different from an 80-year-old with the same acuity. The older person is more likely to be impaired under the conditions of daily life. Measurement and appreciation of visual function should allow better understanding of subjective visual symptoms and allow the clinician to offer appropriate advice for mitigating these impairments. Often simple interventions, such as correcting refractive error, improving lighting, avoiding large changes in light level, increasing contrast, and avoiding glare (perhaps through cataract surgery), can greatly improve not only vision function but quality of life. Many studies have reported that good vision allows for independent living, which is the goal for most elders.

Aged↗
PubMed2004

Educating the educators: increasing grade-school teachers' ability to detect vision problems.

BACKGROUND: The State University of New York College of Optometry/University Optometric Center conducts vision screenings in various public schools in New York City. A study was devised to determine whether teachers' abilities to detect vision problems in their students could be enhanced. METHODS: Students of two different grade schools were screened, in 1998-1999 and again two years later. In 1998-1999, the week before each group of students was to be screened, teachers were asked to indicate which children were felt to have vision problems. In 2000-2001, prior to the screenings, a lecture on vision and its relationship to learning was given to the same teachers who had responded two years earlier, and handouts and brochures delineating vision problems were also given to each teacher. A comparison was then made of the teachers' ability to detect vision problems before and after the teacher education. RESULTS: In the first year, 111 of 377 of children screened (29%) were referred. Teachers correctly identified 39% of the acuity failures and 29% of the functional failures. Two years later, a total of 31% of children were referred. The same teachers correctly identified 68% of the acuity failures and 67% of the functional failures. CONCLUSIONS: There was a statistically significant increase in the ability of teachers to correctly identify children with learning problems based on education. Both the accuracy of identifying children with acuity problems, as well as identifying children with functional visual problems, increased. Based on these results, it is recommended that an in-service lecture be given to school teachers to heighten their awareness of vision problems that may impact learning performance.

Child↗
PubMed1997

Impaired vision in the elderly: a preventable condition.

BACKGROUND: Vision is thought to deteriorate with age as a number of factors in later life endanger eyesight. Assessment of the visual acuity of the elderly and identification of endangering factors help in detecting those with impaired vision which in turn impairs daily activities. OBJECTIVE: This study measured the visual acuity of the senior citizens and identified those with impaired vision. The probable contributing factors for impaired vision were studied with the aim of preventing visual impairment. METHOD: The study was part of a screening campaign for elderly glaucoma in the community. A convenience sample of ambulatory senior citizens from stratified localities had their visual acuity measured with a standard Snellen's chart. The test was repeated with pinholes if the visual acuity was less than 0.5. Those without improvement after pinhole were considered as having impaired vision. People with elevated intraocular pressure by the Pulsair were selected for examination by an ophthalmologist for ocular pathology. RESULTS: For the ambulatory population aged > or = 65 the mean visual acuity of either eye before pinhole was 0.3. Nearly 72% had impaired vision (visual acuity not corrected above 0.5 with pinhole). There was a significant association between this impairment and female sex, history of diabetes mellitus or glaucoma, cataract, and infrequent eye examination. CONCLUSION: Impaired vision is highly prevalent in the elderly ambulatory population, a condition which is preventable by tight surveillance of predisposing factors and regular simple measurement of visual acuity. The primary care setting is most suitable for these activities.

Age Distribution↗
PubMed1998

Vision screening of preschool children: evaluating the past, looking toward the future.

Vision problems of preschool children are detectable with a comprehensive eye examination; however, it is estimated that only 14% of children below the age of 6 years receive an eye examination. Screening is advocated as a cost-effective alternative to identify children in need of further vision care. Thirty-four states recommend or require vision screening of preschool children. Although laws and guidelines exist, only 21% of preschool children are actually screened for vision problems. There is little agreement concerning the best screening methods, and no validated, highly effective model for screening vision of preschool children. Newer screening tests have been designed specifically for preschool populations, and can be administered by lay screeners. Many have not been validated. Several are recommended by states or organizations without convincing scientific evidence of their effectiveness. This paper summarizes current laws and guidelines for preschool vision screening in the United States, reviews advantages and disadvantages of several test procedures, and provides recommendations for developing future preschool vision screening programs.

Child, Preschool↗
PubMed2001

Direction of gaze while walking a simple route: persons with normal vision and persons with retinitis pigmentosa.

PURPOSE: The purpose of this study was to determine whether persons with advanced vision impairment, when walking an unfamiliar route, visually sample the environment in a different manner than do persons with normal vision. METHODS: Direction of gaze was measured in six persons with retinitis pigmentosa (RP) and in three persons with normal vision as they walked an unfamiliar, obstacle-free route while viewing the environment in a head-mounted display. RESULTS: Persons with RP fixated over a larger area in the environment and at different features than did persons with normal vision. Persons with normal vision directed their gaze primarily ahead or at the goal, whereas persons with RP directed their gaze at objects on the walls, downward, or at the layout (i.e., edge-lines or boundaries between walls). The results also showed a significant negative correlation between the horizontal visual field extent of the RP subjects and the proportion of downward-directed fixations. CONCLUSIONS: Persons with advanced vision impairment as a result of RP visually sample the environment in a manner different from persons with normal vision.

Adult↗