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At least 1,279 records · Page 71Linked to original sources
PubMed2002

The effect of letter spacing on reading speed in central and peripheral vision.

PURPOSE: Crowding, the adverse spatial interaction due to proximity of adjacent letters, has been suggested as an explanation for slow reading in peripheral vision. The purpose of this study was to examine whether reading speed can be improved in normal peripheral vision by increasing the letter spacing. Also tested was whether letter spacing imposes a different limit on reading speed of small versus large print. METHODS: Six normal observers read aloud single, short sentences presented on a computer monitor, one word at a time, by rapid serial visual presentation (RSVP). Reading speeds were calculated based on the RSVP exposure durations yielding 80% correctly read words. Letters were rendered in Courier, a fixed-width font. Testing was conducted at the fovea, 5 degrees and 10 degrees in the inferior visual field. The critical print size (CPS) was first determined for each observer by measuring reading speeds for four print sizes, using the standard letter spacing (center-to-center separation of adjacent letters; standard Courier spacing: 1.16 times the width of the lowercase x). Text was then presented at 0.8 x or 1.5x CPS, and reading speed was measured for five letter spacings, ranging from 0.5 times to 2 times the standard spacing. RESULTS: As expected, reading speed was highest at the fovea, decreased with eccentricity, and was faster for the larger print size. At all eccentricities and for both print sizes, reading speed increased with letter spacing, up to a critical letter spacing, and then either remained constant at the same reading speed or decreased slightly for larger letter spacings. The value of the critical letter spacing was very close to the standard letter spacing and did not depend on eccentricity or print size. CONCLUSIONS: Increased letter spacing beyond the standard size, which presumably decreases the adverse effect of crowding, does not lead to an increase in reading speed in central or peripheral vision.

Adult↗
PubMed2002

[The vision of welders in France].

PURPOSE: A study was conducted to measure the impact of welding on the vision of welders. METHODOLOGY: This study was conducted in France by the occupational medicine staff of large companies on 1.131 people, namely 850 welders and 281 control subjects. This investigation included two examinations at the beginning and the end of a year. The investigative procedure examined the different welding processes, the percentage of working time spent on welding activity, the length of exposure in years, as well as the medical variables: the optical correction type and history of ocular traumatology. The Visiotest or the Ergovision were used for the visual examination, equipment in common use by occupational medicine departments. RESULTS: The welders were comparatively young (59.53% of them were less than 45 years old). Moreover, for 69.75% of the welders, more than 75% of their activity was devoted to welding. All currently used welding processes were represented, including the modern PLASMA-TIG welding process. No excessive blood alcohol levels were observed in all subjects, but welders did smoke slightly more than the control subjects (40% vs 33%). Self-medication was rather less frequent among the welders, except as regards the use of eye drops, where the proportions were clearly inverted. Optical correction for hyperopia was similar between the two groups; however, as regards myopia, the welders were corrected less often. Lastly, contact lens use was exceptional among the welders. Nearsightedness varied logically with age, but also, inexplicably, with the welding processes. Vision recovery time after exposure to glare was much longer among the welders, except for the PLASMA-TIG processes. No difference was observed in the other parameters of the study. No change in the visual functions studied was noted between the two examinations. DISCUSSION: The examination techniques used showed no impairment of the studied visual functions, probably because companies use protective and preventive eye care methods. Moreover this study is the first to examine the type of welding used by workers and particularly the modern PLASMA-TIG process. The vision recovery time after exposure to glare seems better for the PLASMA-TIG process may be the result of the lower luminous intensity of this process. CONCLUSION: This study was conducted for preventive purposes to contribute to better monitoring of safety and comfort for welding workers and has shown no alteration of the visual function among welders in general.

Adaptation, Ocular↗
PubMed2003

Followup: a case of acute loss of binocular vision and stereoscopic depth perception. (The misery of acute monovision, having been binocular for 68 years).

This is a continuation of a personal report by a knowledgeable vision scientist, of the loss of binocular vision due to a major vitreous hemorrhage. Please see the initial report for further details. (Romano PE. A case of acute loss of binocular vision and stereoscopic depth perception. (The misery of acute monovision, having been binocular for 68 years) Binocul Vis Strabismus Q 2003; 18:51-55). This report covers months three and four following the hemorrhage. In the two months since the initial report, typical daily problems from this handicap are described. Definite evidence of progressive resolution was finally seen at the end of the third month. The speed of this resolution is about 1% per day!

Acute Disease↗
PubMed2003

Follow-up study on vision health readiness in the military.

A retrospective study reviewed medical records of military personnel who had participated in a vision readiness study the previous year. The review evaluated (1) the number of personnel who returned for an eye examination (as recommended), (2) the number of dilated eye examinations, (3) the number of optical devices ordered, (4) the number of patients requiring continuing treatment, (5) the types of eye disease in personnel who were classified as nondeployable in the original study, and (6) the relationship between patient vision complaints and the need for spectacles. Analyses revealed 44% of military personnel have never had a comprehensive eye examination. Of these personnel who never had an eye examination, 15% to 26% could improve their vision with spectacles. Finally, even though having an eye examination is important, whether or not the individual has had a comprehensive eye examination should not be a significant criterion for deployment.

Female↗
PubMed1992

Development of binocular vision in the kitten's striate cortex.

Studies of the development and plasticity of the visual pathway are well documented, but a basic question remains open: what is the physiological status of the system prior to extensive visual experience? Somewhat conflicting answers have been put forward, and in a major area, binocular vision, reports have ranged from severe immaturity to well-developed maturity. This is an important question to resolve since binocular cells in the visual cortex are thought to be the neural substrate for stereoscopic depth perception. We have addressed this question by recording from single cells in the striate cortex of kittens at postnatal ages 2, 3, and 4 weeks and from adults for comparison. Gratings with sinusoidal luminance distribution are presented to left, right, or both eyes. For each cell, we determine optimal values for orientation and spatial frequency. Relative phase (retinal disparity) is then varied in a dichoptic sequence so that binocular interaction may be studied. Results are as follows. In the normal adult, we have shown in previous work that most binocular interaction in the visual cortex can be accounted for on the basis of linear summation. Results from 3 and 4 week postnatal kittens are closely similar to those from adults. All types of binocular interaction found in adults are present in kittens. This includes phase-specific and non-phase-specific suppression or facilitation. Furthermore, monocular and binocular tuning characteristics are comparable in kittens and adults. The clear changes that occur with age are optimal spatial frequencies and peak responses. In addition, at 2 weeks, there is a substantially higher proportion of monocular cells compared to other ages and correspondingly, lower relative numbers of cells that exhibit phase-specific or suppressive binocular interactions. From increases in optimal spatial frequency and interpupillary distance with age, we calculated predicted changes in binocular disparity thresholds (stereo acuity) with age. Although there are methodological limits with respect to the behavioral testing of young kittens, the predicted results are comparable to some of the values obtained. Considered together, our results show that the physiological apparatus for binocular vision is functional at an early stage in postnatal development. It is possible that the connections that underlie this function are developed rapidly during early postnatal experience. An alternative possibility is that there is an elaborate genetic organization of binocular vision, but our study does not address this issue directly. A combination of these factors may be applicable.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMedDate not supplied

Visual acuity, binocular vision, and ocular muscle balance in VLBW children.

Thirty-four very low birth weight (VLBW) 6-year olds and 31 normal birth weight (NBW) 6-year olds were assessed for visual acuity, binocular vision, and ocular muscle balance. Significantly more of the children in the VLBW group failed the tests of binocular vision and ocular muscle balance. Failure in tests of binocular vision was associated with higher numbers of days on mechanical ventilation and higher number of days in the intensive care nursery during the first months of life.

Child↗
PubMed1991

Use and non-use of low vision aids by visually impaired children.

The results of this study indicated that children do use and benefit from low vision aids and that the child's need for near low vision aids can be predicted from their age, unmagnified reading performance, and visual field characteristics. The use of distance monoculars is less easily predicted. However, many visually impaired children both in mainstream special units and in schools for the blind are not being supplied appropriate low vision aids (LVAs). Many have not had an LVA assessment within 1 year and others are experiencing difficulties with LVAs that could be eliminated or reduced.

Adolescent↗
PubMed1990

The validity of Titmus Vision testing results.

A comparison was made between results obtained through the Titmus Vision Tester and those obtained through more common open field optometric procedures. Specific tests performed with the Titmus Vision Tester included near and distance visual acuities, distance lateral and vertical phorias, color discrimination, and stereo acuity. Results were also obtained using Snellen near and distance charts for visual acuities, Maddox rod for vertical and lateral phorias at distance (neutralized with prism), Ishihara plates for color discrimination, and Stereofly Wirt Dot for stereo acuity. The purpose was to determine whether results obtained by the Titmus Vision Tester are significantly different from those obtained by performing the above specific tests on the patient population.

Adult↗
PubMed1985

Psychophysics of reading. III. A fiberscope low-vision reading aid.

Existing reading aids providing magnification in excess of 6X (24 diopters) are awkward to use, expensive, or not portable. The authors have developed a new type of reading aid, a low-resolution fiberscope, that provides magnification up to 40X (160 diopters), and is easy to use, inexpensive, and portable. The fiberscope consists of an objective-lens assembly, a flexible bundle of optical fibers, and an eyepiece that together transmit an image from the page to the reader's eye. Complete construction details are included. The design is based on the authors' previous findings that reading requires a field of only four characters and a resolution of only 2 cycles/character. After only half an hour of training, a diverse group of low-vision readers read with the fiberscope at rates between 12 and 95 words/minute. Low-vision readers with central field loss had a median reading rate of only 18 words/min, whereas those with intact central fields had a median reading rate of 67 words/min, not far short of the median rate of 73 words/min for normal readers using the fiberscope. This is consistent with the authors' previous findings that low-vision readers with central field loss read much more slowly than those with intact central fields, even when optimal magnification is provided. The authors conclude that the fiberscope may be very useful as an inexpensive portable reading aid for people requiring high magnification.

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

[Light vision and chorioretinal circulation. Study of the effect of procyanidolic oligomers (Endotelon)].

Light vision is a major element of the visual function. However, it varies from one subject to another. Many factors may modify it in the absence of amy retinal pathology (âge, fatigue, stress). A lower resistance to glare and an alteration of scotopic vision are often mentioned during medical visits. We endeavored to obtain a protection with Endotelon in subjects presenting no major retinal or ophthalmological pathology. Endotelon comes in tablets of 50 mg of procyanidolic oligomers. This compound of vegetal origin (from grape seeds) belongs to the chemical class of flavones which selectively fix on collagen and elastin fibers, thus reinforcing the structure of the vascular connective tissue. The drug efficiency on the resistance to glare and on the night morphoscopic vision was demonstrated by means of three tests: Comberg's nyctometer, Beyne's lantern and ergovision. One hundred subjects were tested in two center. In both center, a treated group received 4 tablets of Endotelon a day for five weeks and a control group received no treatment. Two patients stopped the experiment. Nyctometer: the improvement in the visual performances after glare as well as the rapidity with which these results were obtained is very significant compared to the results obtained by the control group. Visual adaptation to low luminances is also improved under treatment. Ergovision tests were performed in two light environments: a standard one and glare. These results support the previous ones. There is a narrow correlation between the decrease in visual performances after a quick retinal glare and the increase in the environmental luminance at the time of inclusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Preschool vision testing with a new device, the Scolatest.

To determine the reliability of results obtained in preschool children by school nurses with a new device for testing vision, the Scolatest, 153 children aged 4 to 5 years were presented with the Snellen E on the standard American Optical projector and with five letters of the Sheridan test (H, O, V, T and X) on the Scolatest. Another 212 children aged 3 to 4 years were presented with the Allen symbols on the projector and with the Pigassou symbols on the Scolatest. The tests with the projector were given at 6 m by an experienced pediatric orthoptist, those with the Scolatest at 2.5 m by a school nurse. The proportion of good responses was higher with the Pigassou symbols than with the Allen symbols. The results with the Sheridan letters and the Snellen E were similar up to 20/30; beyond 20/30 the Snellen E appeared unreliable. The four vision-testing systems were also presented by a school nurse at 2.5 m on the Scolatest to 102 children aged 4 to 5 years (Snellen E and the five Sheridan letters) and 80 children aged 3 to 4 years (Allen and Pigassou symbols). The proportions of good responses were more comparable. The results suggest that a working distance of 2.5 m should be used in testing vision in preschool children. Visual screening at this distance should test acuity beyond the 20/30 equivalence if results comparable to those at 20 feet with the 20/30 standard requirement are to be obtained.

Child, Preschool↗
PubMed1988

Low vision and the elderly patient.

This paper describes special considerations and approaches that are necessary in optometric care of the elderly patient with low vision. Emphasis is placed on case history and presentation of treatment recommendations. Procedures for the systematic assessment of vision are described and there is a discussion of the kinds of low vision aids most commonly prescribed for the elderly.

Aged↗
PubMed1983

The NYSOA vision screening battery--a total approach.

A vision screening battery has been developed by a project team of the New York Optometric Association. This battery screens those visual skills that are important to the academic task demands. This battery is so organized that it can be utilized without the need of a vision care professional. A pre-pilot study was conducted by the New York State Optometric Association and the New York State Educational Department. This battery was a far more sensitive detector of visual problems related to learning than the Snellen alone. This battery was efficiently and effectively utilized by educators and parents without the need of a vision care professional. The battery and statistical study are discussed.

Child↗
PubMed1995

Vision rehabilitation therapy for the bioptic driver.

BACKGROUND: The use of a bioptic telescope for driving purposes has been controversial. This controversy has been fueled by confusion over which vision skills are needed for driving and how they are measured and developed. To make this issue even more complex, there are no standardized programs for evaluating patients and teaching basic vision skills needed to drive safely. METHODS: This paper will address vision skills and abilities which, intuitively, play an important role in driving. We will also propose a training program for the successful development of these skills since they relate to active driving, specifically, with a bioptic telescope. RESULTS: Our experience in working with patients who are partially sighted in the driving program seems to indicate that these patients have confidence in using their bioptic telescopic lens system for driving purposes. They appreciate and recognize the responsibility that comes with the independence that is gained from driving with the bioptic system. CONCLUSIONS: It is our hope that by providing these patients with appropriate care and training, we afford them the opportunity to adjust to their bioptic driving lens system and enjoy more years of independence and safe driving.

Automobile Driving↗
PubMed1993

What the literature says about sports vision.

The demands on the visual system during athletic performance are among the most rigorous of any activity. Because vision influences the capacity of an athlete to perform the tasks of a sport, scientific research has been performed to investigate the link between skill and vision. Most research efforts have been directed toward identifying the visual skills necessary for sports and determining if the skills of athletes differ from those of nonathletes. These efforts, though incomplete, have suggested that certain visual skills are important to performance in selected sports and that the visual skills of athletes and nonathletes do differ. There is as yet a paucity of research to support the hypothesis that the visual skills of athletes can be enhanced by visual training and that enhanced visual skills will result in improved athletic performance. Additional research efforts are needed to answer the many intriguing questions posed by the relationship between vision and sports.

Depth Perception↗
PubMed1977

[Areas of anomalous binocular single vision in small angle concomitant esotropia: evaluation by means of a modification of the v. Graefe technique (author's transl)].

A red filter in front of the fixing eye according to the v. Graefe technique was used in order to detect binocular visual field in patients with anomalous retinal correspondence and small angle esotropia. A striated glass was also placed in front of the deviated eye, in order to check whether single perception was related to suppression or to binocular vision. It has been demonstrated that these patients prevalently enjoy an anomalous binocular vision supported by an anomalous retinal correspondence. The suppression scotoma described by the v. Graefe perimetric technique may therefore in certain cases be in reality areas of single anomalous binocular vision. It has also been seen anomalous retinal correspondence is more deeply rooted at the center than at the periphery of the binocular visual field.

Adolescent↗
PubMed1996

[State of binocular vision and comparative assessment of methods of its study in motor vehicle drivers].

Ophthalmologic study covered 100 truck drivers (categories C and E according to International Classification) aged 21 to 50 and with length of service from 2 to 25 years. Comparative evaluation of various methods studying deep and stereoscopic vision proved that professional drivers have high values of deep and stereoscopic vision. Those values appeared to correlate strongly and positively (r = 0.57). Making a decision on adequacy to driving the stated vehicles, experts should prefer simple and informative method studying stereoscopic vision through lens stereoscope with "three circles" table.

Adult↗