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PubMedDate not supplied

Anthocyanosides of Vaccinium myrtillus (bilberry) for night vision--a systematic review of placebo-controlled trials.

We have systematically reviewed placebo-controlled trials of V. myrtillus-extracted anthocyanosides for evidence of positive effects on night vision. Searches of computerized databases and citations in retrieved articles identified 30 trials with outcome measures relevant to vision in reduced light. Of these, 12 were placebo-controlled. The 4 most recent trials were all randomized controlled trials (RCTs) and were negative in outcome. A fifth RCT and 7 non-randomized controlled trials reported positive effects on outcome measures relevant to night vision. Negative outcome was associated with more rigorous methodology but also with lower dose level and extracts from geographically distinct sources that may differ in anthocyanoside composition. Healthy subjects with normal or above average eyesight were tested in 11 of the 12 trials. The hypothesis that V. myrtillus anthocyanosides improves normal night vision is not supported by evidence from rigorous clinical studies. There is a complete absence of rigorous research into the effects of the extract on subjects suffering impaired night vision due to pathological eye conditions. Evidence from methodologically weaker trials and auxiliary evidence from animal studies, trials of synthetic anthocyanosides, and a recent randomized controlled trial of Ribes nigrum (black currant) anthocyanosides may warrant further trials of V. myrtillus anthocyanosides in subjects with impaired night vision.

Anthocyanins↗
PubMed1999

Impaired color vision associated with diabetic retinopathy: Early Treatment Diabetic Retinopathy Study Report No. 15.

PURPOSE: To report color vision abnormalities associated with diabetic retinopathy. METHODS: Color vision function was measured at baseline in 2,701 patients enrolled in the Early Treatment Diabetic Retinopathy Study, a randomized trial investigating photocoagulation and aspirin in the treatment of diabetic retinopathy. Hue discrimination was measured by the Farnsworth-Munsell 100-Hue test, and errors in color vision were reported as the square root of the total 100-Hue (SQRT 100-Hue) score. RESULTS: Approximately 50% of the Early Treatment Diabetic Retinopathy Study population had color vision scores (SQRT 100-Hue score) worse than 95% of the normal population reported by Verriest and associates. The factors most strongly associated with impaired hue discrimination were macular edema severity, age, and presence of new vessels. A tritan-like defect was prominent and increased in magnitude with increasing severity of macular edema. However, many patients had color discrimination impairment without macular edema. CONCLUSIONS: Impaired color vision is a common observation among participants enrolled in the Early Treatment Diabetic Retinopathy Study. Compared with published data on normal subjects, approximately 50% of the patients in the Early Treatment Diabetic Retinopathy Study had abnormal hue discrimination. Macular edema severity, age, and the presence of new vessels were the factors most strongly associated with impaired color discrimination. A tritan-like defect was prominent and increased in magnitude with increasing severity of macular edema. Impaired color vision should be considered in the evaluation and counseling of patients with diabetic retinopathy.

Adolescent↗
PubMed2004

Robust and efficient vision system for group of cooperating mobile robots with application to soccer robots.

In this paper a global vision scheme for estimation of positions and orientations of mobile robots is presented. It is applied to robot soccer application which is a fast dynamic game and therefore needs an efficient and robust vision system implemented. General applicability of the vision system can be found in other robot applications such as mobile transport robots in production, warehouses, attendant robots, fast vision tracking of targets of interest and entertainment robotics. Basic operation of the vision system is divided into two steps. In the first, the incoming image is scanned and pixels are classified into a finite number of classes. At the same time, a segmentation algorithm is used to find corresponding regions belonging to one of the classes. In the second step, all the regions are examined. Selection of the ones that are a part of the observed object is made by means of simple logic procedures. The novelty is focused on optimization of the processing time needed to finish the estimation of possible object positions. Better results of the vision system are achieved by implementing camera calibration and shading correction algorithm. The former corrects camera lens distortion, while the latter increases robustness to irregular illumination conditions.

Algorithms↗
PubMed1997

Moving vernier in amblyopic and peripheral vision: greater tolerance to motion blur.

The purpose of this study was to examine the hypothesis that higher stimulus velocities could be tolerated in amblyopic and normal peripheral vision. The basis for this hypothesis is that a shift in the spatial scale of processing appears to account for the degradation in vernier acuity for moving stimuli in normal vision, and, to a large degree for the degradation in vernier acuity for stationary stimuli in amblyopic and peripheral vision. Vernier thresholds were determined using a pair of long abutting lines, for velocities ranging between 0 and 8 deg/sec. Comparisons were made between non-amblyopic and amblyopic eyes in two amblyopic observers, and between central and peripheral (5 and 10 deg) vision in two normal observers. We analyzed our threshold vs velocity data using an equivalent noise analysis, and defined the knee of the function, the point at which vernier threshold is elevated by a factor of square root of 2, as the "critical velocity" beyond which image motion degrades vernier acuity. Critical velocities were found to be higher in amblyopic than in nonamblyopic eyes; and higher in peripheral than central vision. Our results are consistent with the predictions from the shift in spatial scale notion--that higher velocity of image motion can be tolerated because of the shift in sensitivity toward lower spatial-frequency filter mechanisms in amblyopic and normal peripheral vision.

Adult↗
PubMed2000

Assessing spatial vision - automated measurement of the contrast-sensitivity function in the hooded rat.

The contrast-sensitivity function (CSF) provides a concise and thorough description of an organism's spatial vision; it is widely used to describe vision in animals and humans, to track developmental changes in vision, and to compare vision among different species. Despite the predominance of rats in neuroscience research, their vision is not thoroughly studied due to the complexity of psychophysical measurement and a generally held notion that rat vision is poor. We therefore designed an economical and rapid method to assess the hooded rat's CSF, using a computer monitor to display stimuli and an infrared touch screen to record responses. A six-alternative forced-choice task presented trials in which a sine-wave grating (S+), varying in spatial frequency and contrast, was displayed at different locations along with five gray stimuli (S-). Nose pokes to the S+ but not the S- produced water reinforcers. Contrasts were tested at each spatial frequency with a simple adaptive procedure until stimulus detection fell below chance. Psychometric functions were obtained by maximum-likelihood fitting of a logistic function to the raw data, obtaining the threshold as the function's point of inflection. As in previous studies with rats, CSFs showed an inverse-U shape with peak sensitivity at 0.12 cyc/deg and acuity just under 1 cyc/deg. The results indicate the present computer-controlled behavioral testing device is a precise and efficient instrument to assess spatial visual function in rats.

Animals↗
PubMed1998

Adaptation of visually guided behavior during reversed vision in schizophrenia: a preliminary study.

This preliminary study evaluated the adaptation of visually guided behavior to reversed vision in schizophrenia. The study included 54 patients who met DSM-III-R criteria for schizophrenia. Visuomotor reaction times (VRTs) during reversed vision were measured in six blocks of 35 consecutive trials. The VRTs of schizophrenics were compared with those of normal subjects. A good fit (R2 = 0.9981) for the adaptation process of VRTs during reversed vision was found with the equation y = 1030 + 1499/x, where x is the order of the block and y is the group mean VRT for each block. The VRTs in schizophrenics were significantly slower than those in normal subjects. However, the adaptation process to reversed vision essentially did not differ from normal. The adaptation of visually guided behavior during reversed vision may involve procedural learning; this task may thus be useful in evaluating such learning. The VRTs during reversed vision may be related to some aspects of symptoms in the patient with schizophrenia and may also be useful in predicting clinical outcome.

Adult↗
PubMed1998

Efficient Learning of VAM-Based Representation of 3D Targets and its Active Vision Applications.

There has been a considerable interest in using active vision for various applications. This interest is primarily because active vision can enhance machine vision capabilities by dynamically changing the camera parameters based on the content of the scene. An important issue in active vision is that of representing 3D targets in a manner that is invariant to changing camera configurations. This paper addresses this representation issue for a robotic active vision system. An efficient Vector Associative Map (VAM)-based learning scheme is proposed to learn a joint-based representation. Computer simulations and experiments are first performed to evaluate the effectiveness of this scheme using the University of Illinois Active Vision System (UIAVS). The invariance property of the learned representation is then exploited to develop several robotic applications. These include, detecting moving targets, saccade control, planning saccade sequences and controlling a robot manipulator.

Journal Article↗
PubMed2002

Scotopic colour vision in nocturnal hawkmoths.

Humans are colour-blind at night, and it has been assumed that this is true of all animals. But colour vision is as useful for discriminating objects at night as it is during the day. Here we show, through behavioural experiments, that the nocturnal hawkmoth Deilephila elpenor uses colour vision to discriminate coloured stimuli at intensities corresponding to dim starlight (0.0001 cd x m(-2)). It can do this even if the illumination colour changes, thereby showing colour constancy-a property of true colour vision systems. In identical conditions humans are completely colour-blind. Our calculations show that the possession of three photoreceptor classes reduces the absolute sensitivity of the eye, which indicates that colour vision has a high ecological relevance in nocturnal moths. In addition, the photoreceptors of a single ommatidium absorb too few photons for reliable discrimination, indicating that spatial and/or temporal summation must occur for colour vision to be possible. Taken together, our results show that colour vision occurs at nocturnal intensities in a biologically relevant context.

Animals↗
PubMed1999

[Color vision in relation to age: a study of normal values].

BACKGROUND: It is difficult to quantify thresholds in most colour vision tests, and this is especially the case for tritan hues, where a strong age-related increase of threshold has been reported. With the development of computer-graphic methods it is possible to remove brightness clues caused by lens absorption. This study attempts to give normative values for colour contrast thresholds and assess the age related changes therein. PATIENTS AND METHODS: 115 patients aged between 6 & 71 years were tested for central and peripheral colour contrast sensitivity. No patient had any systemic or eye disease. As a preliminary, heterochromatic flicker balance between the luminosities of the R and G and B and G phosphors was established, so that all colours subsequently generated were isoluminant for the person tested. Then, using a modified binary search technique, colour contrast thresholds were established using both 2 degree optotypes, for central vision, and a ring, 12.5 degrees in radius for peripheral vision. In the latter case, the observer had to name the position of the missing quadrant in the ring. Stimuli were presented for 200 msec at 1 Hz. Colours were modulated on protan, deutan or tritan colour axis. RESULTS: No correlation between age and central colour vision thresholds was observed. By contrast a significant but only minor increase of peripheral colour vision threshold was observed for the peripheral protan and tritan axis. DISCUSSION: The present system removes luminance clues from colour vision tests and permits both central and peripheral retina to be tested. The results are simple in that the influence of age can be neglected. The variability of threshold results is small, and it is easy to detect the relatively large changes associated with disease. Since high-quality monitors are standardised and calibrated, providing the stimulus parameters described are adhered to, the results given here for upper limits of normal may be used for other similar systems.

Adolescent↗
PubMed1999

On-Line Updating of Spatial Information Druing Locomotion Without Vision.

Two experiments are reported in which the control of locomotion without vision was investigated. In Experiment 1, subjects (N = 10) made similar, although less functional, locomotor adjustments when walking without vision to a target than they did when walking with vision. That result suggests that while walking without vision, the subjects updated their positions on-line with respect to a representation of the target rather than operating from a preformulated action plan. In Experiment 2, there was a significant weakening and loss of functionality of the locomotor adjustments when subjects (N = 10) had to walk without vision the correct distance to the target but in a direction opposite to its true location, as compared with when they walked without vision directly to the target. That finding suggests that the subjects were nonvisually updating their positions not with respect to an abstract representation of the target's distance but with respect to a representation of its relative location within the task environment.

Journal Article↗
PubMed2000

Mathematical leadership vision.

This article is an analysis of a new type of leadership vision, the kind of vision that is becoming increasingly pervasive among leaders in the modern world. This vision appears to offer a new horizon, whereas, in fact it delivers to its target audience a finely tuned version of the already existing ambitions and aspirations of the target audience. The leader, with advisors, has examined the target audience and has used the results of extensive research and statistical methods concerning the group to form a picture of its members' lifestyles and values. On the basis of this information, the leader has built a "vision." The vision is intended to create an impression of a charismatic and transformational leader when, in fact, it is merely a response. The systemic, arithmetic, and statistical methods employed in this operation have led to the coining of the terms mathematical leader and mathematical vision.

Humans↗
PubMedDate not supplied

Prospective trial using Virtual Vision as distraction technique in patients undergoing gastric laboratory procedures.

To determine whether distraction techniques using Virtual Vision, an audiovisual system integrated into a modified pair of glasses, improves tolerance to routine gastric laboratory procedures, a prospective study of 50 patients was done. Patients were allowed to view/hear a travelogue tape during testing. Patients and registered nurses, who performed the procedure, were asked their interpretation of Virtual Vision as a device that improved patient tolerance, impaired the patient's ability to follow directions, or impaired the nurse's ability to perform the procedure. Patients graded the procedure from 1 (unbearable) to 5 (reasonably comfortable) and were asked whether they would use the device for a repeat procedure. For those who had undergone previous procedures, patients were queried regarding their preference for routine testing or Virtual Vision. Improved tolerance to procedures was noted in 82% of the patients as perceived by nurses and patients. Eighteen percent of the nurses and 8% of the patients thought that the auditory insert and glasses impaired the patient's ability to cooperate with the test, whereas 88% and 86%, respectively, thought that Virtual Vision was a valuable distraction technique. Using an ordinal scale for testing tolerance, patients graded their test at a mean of 3.8 (SD 1.25) and 82% expressed a desire to use the system in conjunction with future testing. Twenty-six of 33 patients (79%) who had undergone previous gastric laboratory testing preferred distraction techniques using Virtual Vision to conventional testing. Distraction techniques using a system such as Virtual Vision have the potential to improve patient tolerance to routine gastric laboratory studies.

Adolescent↗
PubMed1993

Effects of target distance and pupil size on letter contrast sensitivity with simultaneous vision bifocal contact lenses.

Using simulated presbyopia we measured the effects of target vergence and pupil size on letter contrast sensitivity while subjects wore accurately centered simultaneous vision bifocal contact lenses. These experiments examined the increase in depth of focus provided by two bifocal contact lenses, and the effects of pupil size on near and distance vision. Monocular contrast sensitivity was assessed with three different designs of soft contact lenses. First, as a single vision control, we measured contrast sensitivity with a Bausch & Lomb, Optima 38 lens corrected for distance. We then measured contrast sensitivity with an Allergan Optical, Hydron Echelon, which is a diffractive simultaneous bifocal and a CIBA Vision, Spectrum, which is a concentric design, center-near, two-zone simultaneous vision bifocal. In general both bifocal contact lenses improved contrast sensitivity at near but decreased contrast sensitivity at distance (when compared to the single vision lens). With a fixed 3.5-mm artificial pupil, the Echelon lens had two clear peaks of sensitivity, one at distance (0.00 D) and one at near (-2.00 D), but the Spectrum lens had no clear peaks. Performance of the Spectrum lens depended on its center zone size. Near (-2.00 D) and distance (0.00 D) contrast sensitivity was measured with pupil sizes that ranged from 1 to 6 mm. The results showed that visual performance with a diffractive lens was almost independent of pupil diameter up to 3 to 4 mm but, as predicted, performance with the two-zone lens depended critically on pupil size.

Contact Lenses, Hydrophilic↗
PubMed2006

Principles and designs of the iseikonic lenses for near vision.

PURPOSE: The purposes of this study were to find the problems of afocal iseikonic lenses as used for near vision and to elaborate the principles and designs of the ideal near iseikonic lenses. METHODS: By analyzing the image-object relationship and imaging processes, the formulae were derived to quantitatively and qualitatively describe two errors of afocal iseikonic lenses as used for near vision: 1) inequality of accommodative demands to both eyes and 2) the difference between the actual and the nominal magnification. Formulae were derived to calculate and design the ideal near iseikonic lenses. RESULTS: For iseikonic lenses now used for near vision, inequality of accommodative demands to both eyes and difference between the actual and nominal magnification increased as the magnification increased and the viewing distance decreased. Afocal iseikonic lenses have significant inequality of accommodative demands to both eyes with 3% magnification at a viewing distance of 25 cm or with 5% magnification at 40 cm. The ideal near iseikonic lenses were found to be flatter than the afocal ones. A series of the ideal near iseikonic lenses were designed with some practical considerations. The central thickness and the refractive index of the lenses affect magnification and lens shape. The thicker the lenses, the higher the magnification. The higher refractive index also gives higher magnification. CONCLUSIONS: Iseikonic lens design is much different for distance and near vision. When the iseikonic lenses are used at a distance other than the designated distance, they will cause blurred vision and artificial aniseikonia as a result of inequality of accommodative demands to both eyes. In research as well as clinical settings, it is necessary to apply the ideal near iseikonic lenses for near vision.

Accommodation, Ocular↗
PubMed2004

Nocturnal colour vision in geckos.

Nocturnal animals are said to sacrifice colour vision in favour of increased absolute sensitivity. This is true for most vertebrates that possess a dual retina with a single type of rod for colour-blind night vision and multiple types of cone for diurnal colour vision. However, among the nocturnal vertebrates, geckos are unusual because they have no rods but three cone types. Here, we show that geckos use their cones for colour vision in dim light. Two specimens of the nocturnal helmet gecko Tarentola (formerly Geckonia) chazaliae were able to discriminate blue from grey patterns by colour alone. Experiments were performed at 0.002 cd m(-2), a light intensity similar to dim moonlight. We conclude that nocturnal geckos can use cone-based colour vision at very dim light levels when humans rely on colour-blind rod vision.

Animals↗
PubMed1993

Colour vision in New World monkeys and the single-locus X-chromosome theory.

The single-locus X-chromosome theory was proposed to explain the unique intra- and inter-species variation in the colour vision found in New World monkeys. The colour vision of only five species of these monkeys has been studied in any detail, and although this data does show some minor deviations from the theory, it is generally consistent with the theory. It has been suggested that the colour vision of New World monkeys may represent an intermediate stage in between the dichromatic colour vision of non-primate mammals and the uniform trichromacy of Old World primates. Alternatively, the colour vision system of New World monkeys may represent a method of obtaining the maximum variation in the colour vision of closely related family groups.

Animals↗
PubMed1988

The effect of exposure duration on the analysis of spatial structure in eccentric vision.

There is some evidence from grating experiments that the transient presentation of a stimulus pattern interferes with the encoding of positional relationships between pattern elements (i.e. the analysis of spatial structure) more in eccentric vision than in central vision. The present study investigated the effect of exposure duration on the analysis of spatial structure in eccentric vision using a task in which the observer discriminated between two mirror symmetric patterns consisting of short line segments. In each trial, the two patterns were flashed for 140 or 500 ms, and the observer had to decide whether the patterns were identical or mirror symmetric. Both constant-size and size-scaled patterns were used in eccentric vision. The longer exposure duration slightly increased the proportion of correct responses in eccentric vision but performance remained distinctly inferior to that in central vision.

Humans↗
PubMed2006

Assessing effects of a media campaign on HIV/AIDS awareness and prevention in Nigeria: results from the VISION Project.

BACKGROUND: In response to the growing HIV epidemic in Nigeria, the U.S. Agency for International Development (USAID) initiated the VISION Project, which aimed to increase use of family planning, child survival, and HIV/AIDS services. The VISION Project used a mass-media campaign that focused on reproductive health and HIV/AIDS prevention. This paper assesses to what extent program exposure translates into increased awareness and prevention of HIV/AIDS. METHODS: This analysis is based on data from the 2002 and 2004 Nigeria (Bauchi, Enugu, and Oyo) Family Planning and Reproductive Health Surveys, which were conducted among adults living in the VISION Project areas. To correct for endogeneity, two-stage logistic regression is used to investigate the effect of program exposure on 1) discussion of HIV/AIDS with a partner, 2) awareness that consistent condom use reduces HIV risk, and 3) condom use at last intercourse. RESULTS: Exposure to the VISION mass media campaign was high: 59%, 47%, and 24% were exposed to at least 1 VISION radio, printed advertisement, or TV program about reproductive health, respectively. The differences in outcome variables between 2002 baseline data and the 2004 follow-up data were small. However, those with high program exposure were almost one and a half (Odds Ratio [O.R.] = 1.47, 95% Confidence Interval [C.I.] 1.01-2.16) times more likely than those with no exposure to have discussed HIV/AIDS with a partner. Those with high program exposure were over twice (O.R. = 2.20, C.I. 1.49-3.25) as likely as those with low exposure to know that condom use can reduce risk of HIV infection. Program exposure had no effect on condom use at last sex. CONCLUSION: The VISION Project reached a large portion of the population and exposure to mass media programs about reproductive health and HIV prevention topics can help increase HIV/AIDS awareness. Programs that target rural populations, females, and unmarried individuals, and disseminate information on where to obtain condoms, are needed to reduce barriers to condom use. Improvements in HIV/AIDS prevention behaviour are likely to require that these programmatic efforts be continued, scaled up, done in conjunction with other interventions, and targeted towards individuals with specific socio-demographic characteristics.

Acquired Immunodeficiency Syndrome↗