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PubMed2003

Molecular analysis of the evolutionary significance of ultraviolet vision in vertebrates.

Many fish, amphibians, reptiles, birds, and some mammals use UV vision for such basic activities as foraging, mate selection, and communication. UV vision is mediated by UV pigments in the short wavelength-sensitive type 1 (SWS1) group that absorb light maximally (lambda max) at approximately 360 nm. Reconstructed SWS1 pigments of most vertebrate ancestors have lambda max values of approximately 360 nm, whereas the ancestral avian pigment has a lambda max value of 393 nm. In the nonavian lineage, UV vision in many modern species is inherited directly from the vertebrate ancestor, whereas violet vision in others has evolved by different amino acid replacements at approximately 10 specific sites. In the avian lineage, the origin of the violet pigment and the subsequent restoration of UV pigments in some species are caused by amino acid replacements F49V/F86S/L116V/S118A and S90C, respectively. The use of UV vision is associated strongly with UV-dependent behaviors of organisms. When UV light is not available or is unimportant to organisms, the SWS1 gene can become nonfunctional, as exemplified by coelacanth and dolphin.

Amino Acid Sequence↗
PubMed1994

The Influence of Skill and Intermittent Vision on Dynamic Balance.

Two experiments are reported in which expert and novice gymnasts were required to walk across a balance beam as quickly as possible in various vision conditions. In Experiment 1, experts walked faster than novices in all vision conditions, showing the greatest superiority when vision was completely eliminated. Novices were more dependent on vision and were able to maintain their performance as long as a visual sample was available every 250 ms (i.e: 4-Hz samples).The results of Experiment 2 indicate that differences between expert and novice performers in the no-vision condition were not related to the use of a short-term visual representation of the movement environment. Our movement time findings are problematic for specificity of learning models of skill acquisition. As well, film data collected in Experiment 2 were not consistent with models that propose a transition from closed-loop to open-loop control.

Journal Article↗
PubMed1990

Is the quality of vision with contact lenses adequate? Not only adequate but often superior.

Two factors govern the quality of vision with contact lenses (CLs): the fit and movement of the lens and the adequacy of its optics. Studies have not demonstrated any inherent inadequacies in material or design parameters that might account for visual difficulties in lens wearers. To the contrary, thickness, water content, and fit can be varied within clinically acceptable ranges without compromising vision. A poorly fitted lens, however, can cause excessive corneal edema and consequent visual problems. Poor vision may also result from uncorrected refractive error, the development of an unstable optical surface, or the use of a lens material that is inherently inadequate for a given patient. Such causes of visual dysfunction can usually be avoided through better fitting, better lens care, more careful refraction, or better patient-lens matching. Specialized lens designs can sometimes be used to correct vision problems. Certain types of rigid front-surface aspheric lenses, for example, provide astigmats with even better visual correction than spherical rigid lenses or spectacles, but the improvement is small and highly patient dependent. Similarly, although soft toric lenses can provide good vision, it is often technically difficult to orient and stabilize the correcting cylinder.

Astigmatism↗
PubMed1990

Is the quality of vision with contact lenses adequate? Not in all instances.

There are several circumstances in which contact lenses (CLs) provide vision inferior to that possible with spectacles. Over time, both soft and rigid gas-permeable (RGP) lenses accumulate deposits that can cloud vision. RGP lenses are especially prone to scratching; some varieties may even become crazed, giving a spiderweb quality to vision. Certain uncommon corneal complications associated with lens wear--infection, neovascularization, ulcers, and severe epithelial edema--may also impair vision, sometimes permanently. CLs often provide less than optimal vision for patients with presbyopia or severe astigmatism. Difficulties with axis stabilization arise with both soft and rigid toric lenses, and these can take several attempts to resolve. Monovision fitting currently offers the best option for presbyopes, but it has an effect on stereopsis, compromising depth perception. Furthermore, patients often require considerable time before adapting to monovision lens use. Finally, even under normal circumstances, certain inherent features of CLs can diminish visual acuity. The water in soft lenses diffuses light; the loss of visual crispness is particularly notable with high-water-content lenses. On the other hand, the small diameter of RGP lenses often contributes to ghosting--a phenomenon in which the edge of the lenses is visible whenever the pupils are widely dilated.

Astigmatism↗
PubMed2002

Testing night vision goggles in a dark outside environment.

BACKGROUND: People with degenerative retinal diseases such as retinitis pigmentosa, may have adequate day vision but suffer from poor night vision. We have tested newly developed night vision goggles (NVG) to help these patients overcome their night blindness, thereby promoting more opportunities for normal activities at night or in the dark. METHODS: A total of 42 subjects with night blindness due to retinitis pigmentosa, choroideremia, cone rod dystrophy, or Bardet Biedl syndrome were recruited and clinically examined (visual acuity, visual field, and contrast sensitivity). Using an experienced mobility trainer, we tested binocular NVG on the subjects in two locations: a dark room and a 1 to 2 h outside course at night that provided different levels of difficulties (i.e., obstacles, brightness, and contrast). The assessment of which patients benefited from the NVG was predominantly based on the subjective evaluation of the mobility trainer, followed by their graded responses on two questionnaires. RESULTS: Based on the evaluation of the mobility trainer, 23 (61%) of the 42 subjects experienced improved mobility and orientation with the NVG outdoors, and 19 (39%) subjects did not. The ophthalmic data demonstrated that a visual acuity better than 20/100 and a visual field > 5 degrees (Goldmann perimetry III4) is necessary to benefit from NVG usage. In addition, subjective responses on increased mobility and independence were positively correlated with successful NVG testing. CONCLUSIONS: Night vision goggles have the ability to improve poor night vision in subjects with visual acuity > 20/100 and a visual field > or = 5 degrees (Goldmann: III4). In so doing, NVG can help overcome the obstacles experienced by many people suffering from night blindness. NVG, therefore, have the potential to greatly improve quality of life.

Adolescent↗
PubMedDate not supplied

Winning loyalty with a vision and a corporate soul.

This article provides insight and practical application for how to improve patient satisfaction and loyalty through a vision with a corporate soul. This article shows from actual experience that the chief executive officer must set the vision for the organization. The vision is key to an organization's ability to win loyalty. Without a vision to become great, an organization will never fulfill its potential to best serve its community. Essential to the vision is developing a corporate soul that embraces the intangibles of the human spirit of sensing the needs of others through meaning, purpose, empathy, caring, and sharing. Although recognizing that the tangibles of revenue, expenses, patient volume, and profit margin are necessary, addressing the intangibles is critical to long-term sustainability.

Health Facility Administrators↗
PubMed2001

Fruits, foliage and the evolution of primate colour vision.

Primates are apparently unique amongst the mammals in possessing trichromatic colour vision. However, not all primates are trichromatic. Amongst the haplorhine (higher) primates, the catarrhines possess uniformly trichromatic colour vision, whereas most of the platyrrhine species exhibit polymorphic colour vision, with a variety of dichromatic and trichromatic phenotypes within the population. It has been suggested that trichromacy in primates and the reflectance functions of certain tropical fruits are aspects of a coevolved seed-dispersal system: primate colour vision has been shaped by the need to find coloured fruits amongst foliage, and the fruits themselves have evolved to be salient to primates and so secure dissemination of their seeds. We review the evidence for and against this hypothesis and we report an empirical test: we show that the spectral positioning of the cone pigments found in trichromatic South American primates is well matched to the task of detecting fruits against a background of leaves. We further report that particular trichromatic platyrrhine phenotypes may be better suited than others to foraging for particular fruits under particular conditions of illumination; and we discuss possible explanations for the maintenance of polymorphic colour vision amongst the platyrrhines.

Animals↗
PubMed2004

Efficient migration of complex off-line computer vision software to real-time system implementation on generic computer hardware.

This paper addresses the problem of migrating large and complex computer vision code bases that have been developed off-line, into efficient real-time implementations avoiding the need for rewriting the software, and the associated costs. Creative linking strategies based on Linux loadable kernel modules are presented to create a simultaneous realization of real-time and off-line frame rate computer vision systems from a single code base. In this approach, systemic predictability is achieved by inserting time-critical components of a user-level executable directly into the kernel as a virtual device driver. This effectively emulates a single process space model that is nonpreemptable, nonpageable, and that has direct access to a powerful set of system-level services. This overall approach is shown to provide the basis for building a predictable frame-rate vision system using commercial off-the-shelf hardware and a standard uniprocessor Linux operating system. Experiments on a frame-rate vision system designed for computer-assisted laser retinal surgery show that this method reduces the variance of observed per-frame central processing unit cycle counts by two orders of magnitude. The conclusion is that when predictable application algorithms are used, it is possible to efficiently migrate to a predictable frame-rate computer vision system.

Algorithms↗
PubMed2001

A practical guide to low vision management of patients with diabetes.

iabetic retinopathy is the leading cause of low vision and blindness in developed countries. Optometrists have an important role in the detection of diabetic-related eye disease. They are also well-placed to manage patients with reduced vision due to diabetes. In 1998, visual rehabilitation information was analysed from 590 visually impaired patients attending the multidisciplinary Low Vision Clinic at Kooyong in Melbourne, Australia. Diabetes was the primary cause of vision loss in 43 (7.3 per cent) of the patients. This paper investigates the characteristics of these 43 patients and the strategies employed to assist them. In doing so we hope to assist practitioners in managing patients with low vision due to diabetes.

Journal Article↗
PubMed2004

Evolution of vertebrate colour vision.

Recent years have witnessed a growing interest in learning how colour vision has evolved. This trend has been fuelled by an enhanced understanding of the nature and extent of colour vision among contemporary species, by a deeper understanding of the paleontological record and by the application of new tools from molecular biology. This review provides an assessment of the progress in understanding the evolution of vertebrate colour vision. In so doing, we offer accounts of the evolution of three classes of mechanism important for colour vision--photopigment opsins, oil droplets and retinal organisation--and then examine details of how colour vision has evolved among mammals and, more specifically, among primates.

Animals↗
PubMed1989

Colour vision in a family with Sorsby's dystrophy.

Fraser & Wallace (1971) investigated a family with Sorsby's dystrophy, and found a high prevalence of a mild red-green colour deficiency. Using a battery of tests, I re-examined the colour vision of members of the family at risk of developing the disease. I conclude that the mild colour vision defect is classical sex linked recessive deuteranomaly occurring adventiously in the family; its high prevalence is due to its being introduced by at least 3 persons marrying into the family. Two alternative hypotheses of the colour vision deficiency are that it is an acquired disorder which is a prodromal sign of the dystrophy or that it is inherited in an autosomal dominant manner. However, these hypotheses were rejected because the colour vision deficiency had the characteristics of a typical sex linked disorder. These findings emphasize that it is important to exclude any co-existing inherited colour vision defect when defining the clinical features of any retinal dystrophy by careful evaluation of unaffected family members.

Adolescent↗
PubMed1993

Developing organisational vision in general practice.

Vision is a fashionable but ill defined term in management circles. Nevertheless, it embodies a significant concept related to guiding an organisation from present realities, through opportunities and hazards, to a viable future. Until recently a typical general practice could assume a stable external environment, but now it is caught up in the uncertainties stemming from the NHS reforms. For such a practice to undertake effective strategic planning it will have to develop a vision connecting the present with aspirations for the future. While vision is usually considered to be an individual talent, it is possible to develop a collective organisational vision within a general practice, and the small size of general practices makes this relatively easy. The vision needs to be broad; it needs to be continuous; and its capacity to predict the future needs to be monitored.

Family Practice↗
PubMed1982

Color vision in the spider monkey (Ateles).

Spectral sensitivity and color vision were investigated in 2 spider monkeys (Ateles) using a forced-choice discrimination paradigm. The increment-threshold spectral sensitivity functions of both animals were very similar to those of normal human trichromats; all had three regions of peak sensitivity located at 440-460, 520-540, and 670-620 nm. However, color vision tests (neutral point, anomaloscope, and wavelength discrimination) indicated that at least two qualitatively different types of color vision exist among spider monkeys. The female tested had essentially normal trichromatic color vision (although her anomaloscope match was shifted slightly in the deutan direction) with acute wavelength discrimination. The male, however, was clearly a protanomalous trichromat. He required much more red light in a red/green mixture to match a standard yellow than did normal trichromats. This variation in color vision is discussed in the context of an analogous variation known to exist among other South American monkeys.

Animals↗
PubMed1994

Visual acuity, color vision, and visual search performance at sea.

Visual acuity and color vision were tested during a search and rescue exercise at sea. Fifty-seven watchkeepers searched for orange and yellow life rafts during daylight and for lighted and unlighted life rafts at night with night vision goggles. There were 588 individual watches of one hour each. Measures of wind, waves, and weather were used as covariates. Daytime percentage detection was positively correlated with low-contrast visual acuity and negatively correlated with error scores on Dvorine pseudoisochromatic plates and the Farnsworth color test. Performance was better during the first half-hour of the watch. Efficiency calculations show that color vision selective screening at one standard deviation above the mean would increase daylight search performance by 10% and that one standard deviation visual acuity selection screening would increase performance by 12%. There was no relationship between either acuity or color vision and life raft detection using night vision goggles.

Color Perception↗
PubMed2002

Pharmacokinetics and pharmacodynamics of a new formulation of recombinant human growth hormone administered by ZomaJet 2 Vision, a new needle-free device, compared to subcutaneous administration using a conventional syringe.

The objective of the present study was to investigate the applicability of a new human growth hormone (Zomacton) formulation, administered both by a conventional syringe and by a new needle-free device (ZomaJet 2 Vision). The study was performed according to a randomized, controlled, three-period crossover design. On 3 separate days, all subjects received in a random order a single subcutaneous injection of 1.67 mg hGH as follows: Zomacton 4 mg/ml conventional syringe administration (Treatment A), Zomacton 10 mg/ml conventional syringe administration (Treatment B), or Zomacton 10 mg/ml ZomaJet 2 Vision administration (Treatment C). The pharmacokinetic parameters were assessed for the individual subjects in each group by noncompartmental methods. Bioequivalence was assessed based on log-transformed AUC and C(max) values. To investigate the effectiveness of two formulations and the different administration methods, the pharmacodynamic parameters (insulin-like growth factor-1 [IGF-1] and free fatty acids [FFA]) were also evaluated. No subjects were withdrawn due to adverse events. The local tolerance assessment (assessed by inspection)revealed no differences between ZomaJet2 Vision application and conventional injections by syringe. Administration of the new hGH formulation by syringe was found to be bioequivalent with the reference treatment, both based on AUC and C(max) values; the new formulation administered by use of ZomaJet 2 Vision was found to be bioequivalent based on AUC values only. When using the ZomaJet 2 Vision, the absorption of hGH was faster, resulting in higher C(max) values. The maximum hGH serum concentration of around 20 ng/ml was observed 3.5 to 4 hours after drug administration. The terminal half-life was found to be around 2.5 hours. Comparison of the pharmacodynamic profiles (both IGF-1 and FFA) demonstrated bioequieffectiveness. These results support the use of jet injectors as a viable alternative to the traditional injection pens.

Adult↗
PubMed2003

Vision related quality of life and topical glaucoma treatment side effects.

BACKGROUND: Local tolerance of topical glaucoma treatment is important to achieve a good compliance. The aim of this study was to evaluate the consequences of local anti-glaucoma drug side effects on the vision-related quality of life (QoL). METHODS: A mail survey was sent to 20,000 homes of a panel representative of the French population asking whether one member of the family was suffering from ocular hypertension (OHT) or glaucoma. (POAG) A computer-assisted telephone interviewing system was used to confirm self-reported glaucoma, to describe the disease and its treatment, and medical item consumption. Vision-related QoL was assessed with the NEI-VFQ-25 (National Eye Institute Visual - Function Questionnaire) and local tolerance with the COMTOL (Comparison of Ophthalmic Medications for TOLerability). RESULTS: 13,352 homes (66.7%) answered the mail. 581 people declared they were suffering from glaucoma or OHT. Prevalence was 1.8%, increasing with age. 204 patients were selected at random Their NEI-VFQ-25 global score showed an overall good QoL. Two domain scores showed some deterioration: general health and driving. 62.4% of the patients cited at least one local side effect. 25.4% had burning, 20.8% blurred vision and 20.2% tearing. Poor vision related QoL was associated with the presence of local side effects leading to poor perceived treatment satisfaction. Dissatisfied patients visited their ophthalmologist more frequently. CONCLUSION: Based on a representative French sample, poor vision related QoL was associated with topical drug side effects that also impact patient satisfaction and compliance. Longitudinal data collection should be performed to confirm our findings.

Administration, Topical↗
PubMed1989

"Tho' she kneel'd in that place where they grew..." The uses and origins of primate colour vision.

The disabilities experienced by colour-blind people show us the biological advantages of colour vision in detecting targets, in segregating the visual field and in identifying particular objects or states. Human dichromats have especial difficulty in detecting coloured fruit against dappled foliage that varies randomly in luminosity; it is suggested that yellow and orange tropical fruits have co-evolved with the trichromatic colour vision of Old World monkeys. It is argued that the colour vision of man and of the Old World monkeys depends on two subsystems that remain parallel and independent at early stages of the visual pathway. The primordial subsystem, which is shared with most mammals, depends on a comparison of the rates of quantum catch in the short- and middle-wave cones; this system exists almost exclusively for colour vision, although the chromatic signals carry with them a local sign that allows them to sustain several of the functions of spatiochromatic vision. The second subsystem arose from the phylogenetically recent duplication of a gene on the X-chromosome, and depends on a comparison of the rates of quantum catch in the long- and middle-wave receptors. At the early stages of the visual pathway, this chromatic information is carried by a channel that is also sensitive to spatial contrast. The New World monkeys have taken a different route to trichromacy: in species that are basically dichromatic, heterozygous females gain trichromacy as a result of X-chromosome inactivation, which ensures that different photopigments are expressed in two subsets of retinal photoreceptor.

Animals↗
PubMed2004

Patterns of vision care among Medicaid-enrolled children.

OBJECTIVE: To describe patterns of vision care among Medicaid-enrolled children. METHODS: We evaluated claims data over a 1-year period among children who were 18 years and younger, living in Michigan, and continuously enrolled in Medicaid but did not have a complex medical condition or were disabled. For this study, vision care comprised eye care services provided by optometrists or ophthalmologists and lens services, including dispensing and fitting of corrective lenses. RESULTS: Children in rural counties had increased odds of receiving eye care (odds ratio [OR]: 1.24) or lens services (OR: 1.22) compared with those in urban counties. In urban counties, non-Hispanic white children had greater odds than Hispanic or nonwhite children to have eye care (OR: 1.37) and lens services (OR: 1.37). An increasing supply of eye care professionals per population within a county was associated with decreased vision care in urban counties and slightly increased eye care and no changes in lens services in rural counties. Urban children who received mostly fee-for-service Medicaid had greater odds of receiving vision care than those with longer periods of managed care. Rural children who received mostly fee-for-service Medicaid had greater odds of eye care but similar odds of lens services. Regardless of urban/rural status, girls had increased odds of receiving eye care (OR: 1.24 for urban, 1.20 for rural) and lens services (OR: 1.36 for urban, 1.24 for rural). CONCLUSIONS: Patterns emerged that suggest underutilization or overutilization of vision care services. Such differences may have an impact on the development of children or waste limited health care resources.

Child↗