bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of under and over refractive correction on visual performance and spectacle lens acceptance
Authors: Atchison David A. , Schmid Katrina L. , Edwards Katie P. , Muller Sharon M. , Robotham Jayne 
Published: March 2003

SummaryAs a follow‐on from a previous study by Miller, Kris and Griffiths (1997, Optom. Vis. Sci.84, 521–526), we investigated the effect of small prescription errors on spatial visual performance and spectacle lens acceptability. We included both negative and positive errors and binocular and monocular errors. Data were collected on 15 young adult subjects. Clinical measures were taken of pupil size, ocular dominance, binocular visual acuity, negative and positive relative accommodation, distance and near heterophorias, and stereopsis. Visual performance was measured with the best correction and for ±0.50 D spherical binocular and monocular errors. Subjects wore spectacles, each containing a different error in turn, for 2 days and compared them with a reference pair. Following the wearing period subjects assessed the performance of the spectacles by completing a short questionnaire. The only ocular tests for which these small prescription errors had significant effects were binocular visual acuity and negative relative accommodation. No significant relationship was observed between any of the clinical test results and overall lens acceptance. Despite this, the reference pair was generally perceived as better than the test pairs containing errors, and a considerable proportion of subjects reported pairs with errors as being unacceptable. In conclusion, the questionnaire findings support the need for both accurate monocular and binocular refractions. Subjects differed in their criteria for judging lens acceptability.
Optometrists' examination and referral practices for patients presenting with flashes and floaters
Authors: Alwitry A. , Chen H. , Wigfall S. 
Published: March 2003

Introduction: Patients experiencing flashes and floaters commonly present to their optometrist. Some of these patients may have significant pathology, yet there is a great deal of variability with regard to examination technique and referral practice. Methods: A questionnaire survey was undertaken to determine the current management of patients presenting to their optometrist with flashes and floaters. All practising community optometrists within Southern Derbyshire received a questionnaire and 74 (56.9%) completed replies were received. Results: Optometrists estimated that an average of 14 patients per month per optometrist presented with symptoms of flashes and/or floaters. Mydriasis was utilised routinely for examination in approximately half of the patients. Mean relative confidence was 2.0 at identifying a vitreous haemorrhage and 6.5 for vitreous pigment (complete confidence = 0, complete lack of confidence = 10). Eight percent of responders were unfamiliar with the clinical sign of vitreous pigment, and 17% identifying this sign did not refer all such patients to the hospital services. Conclusions: Patients presenting to their optometrists with flashes and/or floaters make up a sizeable part of the community optometrist's workload and the management of these patients is highly variable. A large proportion of these patients are examined without mydriasis, even in the presence of various risk factors for retinal detachment. There is a relative lack of confidence amongst optometrists with regards the detection of vitreous pigment and the prognostic implications of this finding. Educational measures such as study days may help the level of understanding and heighten the appreciation of the implications of flashes and floaters and the various clinical signs encountered.
Effect of β‐adrenoceptor antagonists on autonomic control of ciliary smooth muscle
Authors: Winn Barry , Culhane Helena M. , Gilmartin Bernard , Strang Niall C. 
Published: March 2003

Abstract Purpose: Pharmacological intervention with peripheral sympathetic transmission at ciliary smooth muscle neuro‐receptor junctions has been used against a background of controlled parasympathetic activity to investigate the characteristics of autonomic control of ocular accommodation.Methods: A continuously recording infra‐red optometer was used to measure accommodation on a group of five visually normal emmetropic subjects under open‐ and closed‐loop conditions. A double‐blind protocol between saline, timolol and betaxolol was used to differentiate between the localised action on ciliary smooth muscle and effects induced by changes in stimulus conditions. Data were collected before and 45 min following the instillation of saline, timolol or betaxolol. Open‐loop post‐task decay was investigated following 3 min sustained near fixation of a stimulus placed 3 D above the subject's pre‐task tonic accommodation level. Closed‐loop dynamic responses were recorded for each treatment condition while subjects viewed sinusoidally (0.05–0.6 Hz) or stepwise vergence‐modulated targets over a 2 D range (2–4 D).Results: Open‐loop data demonstrate a rapid post‐task regression to pre‐task tonic accommodation levels for saline and betaxolol control conditions. A slow positive post‐task shift was induced by timolol indicating that sympathetic inhibition contributes to accommodative adaptation during sustained near vision. Closed‐loop accommodation responses to temporally modulated sinusoidal stimuli showed characteristic features for both saline and betaxolol control conditions. Timolol induced a reduced gain for low‐ and mid‐temporal frequencies (< 0.3 Hz) but did not affect the response at higher temporal frequencies. Response times to stepwise stimuli increased following the instillation of timolol for the near‐to‐far fixation condition compared with the controls and was related to the period of sustained prior fixation.Conclusions: Modulation of accommodation under open‐ and closed‐loop conditions by a non‐selective β‐blocker is consistent with the temporal and inhibitory features of sympathetic innervation to ciliary smooth muscle. Although parasympathetic innervation predominates there is evidence to support a role for sympathetic innervation in the control of ocular accommodation.
Vision status of children with oculocutaneous albinism
Authors: Oduntan A. O. , Raliavhegwa M. , Lund P. M. 
Published: March 2003

Purpose:  Black South African children with oculocutaneous (OCA) albinism were examined optometrically to establish the level of vision improvement that could be achieved following optical correction.Methods:  The children (N = 153) (males 50.3%; females 49.7%), aged 7–17 years (mean = 10.76 ± 2.25 years) were examined with a logMAR VA chart, cover tests, retinoscopy (dry), subjective refraction, Vistech contrast sensitivity test, ophthalmoscopy, Randot stereotest, Ishihara and Farnsworth Panel D‐15 tests.Results:  Many (34.6%) of the children had strabismus, 2–25 prism dioptres. Uncorrected distance VAs were: OD: Finger counting (FC) to 6/7.5 − 2, OS: 6/7.5 + 2 to 6/7.5 − 3, OU: 6/60 − 1 to 6/7.5. Most (67.6%) of the children had myopia. Others (30.8%) had hyperopia or emmetropia (1.7%). Astigmatism was present in 92.25% of the children. The nearest equivalent spherical powers were: OD: −12.00 to +2.75 D (mean = −1.48 ± 2.28 D) and OS: −8.00 to +5. 75 D (mean = 1.36 ± 2.18 D).Following optical correction, VA improvement ranged from one to three lines in 71.2% of the children. The corrected VAs were, OD FC to 6/6 − 1, OS 6/7.5 + 2 to 6/6 − 1, and OU 6/60 to 6/6. Many (84.3%) of the children had corrected VA worse than 6/18 in the better eye and were therefore classified as partially sighted or blind (VA worse than 3/60). Stereoacuity was poor (500–70 sec arc) in most (89.5%) of the children, whilst others could not perceive the minimum 500 sec arc on the test. Contrast sensitivity was poor, maximum spatial frequency being 18 cpd with peak sensitivity at 3 cpd. Many (83%) of the children, however, had normal colour vision.Conclusion:  These children with OCA had poor VA, which could be improved significantly with optical correction. Their poor contrast sensitivity and depth perception, however, were not improved. Most of the children with OCA had normal colour vision.
The effect of changing from glasses to soft contact lenses on myopia progression in adolescents
Authors: Fulk George W. , Cyert Lynn A. , Parker Donald E. , West Roger W. 
Published: March 2003

AbstractAt the end of a clinical trial of bifocals as myopia treatment, subjects were allowed to select any type of optical correction they wished and were asked to return in 1 year. This report gives results of that last examination with emphasis on how progression rates differed between those remaining in their original type of glasses compared with those who switched to soft contact lenses. We found that myopia progressed at an age‐adjusted average rate of 0.74 D in 19 children who switched to soft contact lens wear compared with 0.25 D for 24 children remaining in glasses (p < 0.0001). Increased growth of the vitreous chamber appeared to account for much of this excess myopia progression, although the difference in that variable did not reach statistical significance (p = 0.101). We also noted a 0.203 D steepening in the corneal curvature in contact lens wearers compared with spectacle wearers whose corneas steepened very little (0.014 D, p = 0.007). Soft contact lens wear was also accompanied by a greater change in the near‐point phoria which moved 4.5 prism dioptres in the exo direction compared with spectacle wearers who experienced only a 1.4 prism dioptre divergent shift (p = 0.048).
Nutritional Assessment of the Oral Cavity
Authors: Deen Darwin 
Published: March 2003

AbstractThe oral cavity reflects the general state of health of the patient. A thorough examination of the oral cavity will provide clinicians with information important to assessment of the patient. Through this exam, clinicians can diagnose specific oral diseases and relevant vitamin and mineral deficiencies or toxicities. This article reviews the appropriate procedures for examination of the mouth, tongue, teeth, and gums and discusses various abnormalities and their potential etiologies. It includes case examples illustrative of patients who might present to a primary care practice.
Selenium, an Antioxidant Nutrient
Authors: Burk Raymond F. 
Published: March 2003

AbstractSelenium is an essential constituent of a number of enzymes, some of which have antioxidant functions. Deficiency of the element in animals makes them susceptible to injury by certain types of oxidative stress. At least 1 human disease occurs only in selenium‐deficient individuals. Therefore, it seems prudent to avoid selenium deficiency. The plasma (or serum) selenium concentration is often used to assess selenium nutritional status. A plasma selenium concentration of 8 μg/dL or greater in a healthy subject indicates that plasma selenoproteins are optimized and the subject is selenium replete. The Third National Health and Nutrition Examination Survey determined plasma selenium in 17,630 subjects in the United States. Its results indicate that more than 99% of the subjects studied were selenium replete. The Institute of Medicine has set the Recommended Dietary Allowance for selenium at 55 μg per day for adults. Since most estimates of selenium intake in the United States are 80 μg per day or greater, routine selenium supplementation is not recommended in the United States.
High‐T, low‐P metamorphism in the Palaeoproterozoic Halls Creek Orogen, northern Australia: the middle crustal response to a mantle‐related transient thermal pulse
Authors: Bodorkos S. , Sandiford M. , Oliver N. H. S. , Cawood P. A. 
Published: March 2003

AbstractHigh‐T, low‐P metamorphic rocks of the Palaeoproterozoic central Halls Creek Orogen in northern Australia are characterised by low radiogenic heat production, high upper crustal thermal gradients (locally exceeding 40 °C km−1) sustained for over 30 Myr, and a large number of layered mafic‐ultramafic intrusions with mantle‐related geochemical signatures. In order to account for this combination of geological and thermal characteristics, we model the middle crustal response to a transient mantle‐related heat pulse resulting from a temporary reduction in the thickness of the mantle lithosphere. This mechanism has the potential to raise mid‐crustal temperatures by 150–400 °C within 10–20 Myr following initiation of the mantle temperature anomaly, via conductive dissipation through the crust. The magnitude and timing of maximum temperatures attained depend strongly on the proximity, duration and lateral extent of the thermal anomaly in the mantle lithosphere, and decrease sharply in response to anomalies that are seated deeper than 50–60 km, maintained for <5 Myr in duration and/or have half‐widths <100 km. Maximum temperatures are also intimately linked to the thermal properties of the model crust, primarily due to their influence on the steady‐state (background) thermal gradient. The amplitudes of temperature increases in the crust are principally a function of depth, and are broadly independent of crustal thermal parameters. Mid‐crustal felsic and mafic plutonism is a predictable consequence of perturbed thermal regimes in the mantle and the lowermost crust, and the advection of voluminous magmas has the potential to raise temperatures in the middle crust very quickly. Although pluton‐related thermal signatures significantly dissipate within <10 Myr (even for very large, high‐temperature intrusive bodies), the interaction of pluton‐ and mantle‐related thermal effects has the potential to maintain host rock temperatures in excess of 400–450 °C for up to 30 Myr in some parts of the mid‐crust. The numerical models presented here support the notion that transient mantle‐related heat sources have the capacity to contribute significantly to the thermal budget of metamorphism in high‐T, low‐P metamorphic belts, especially in those characterised by low surface heat flow, very high peak metamorphic geothermal gradients and abundant mafic intrusions.
Polyphase zircon in ultrahigh‐temperature granulites (Rogaland, SW Norway): constraints for Pb diffusion in zircon
Authors: Möller A. , O'Brien P. J. , Kennedy A. , Kröner A. 
Published: March 2003

AbstractSHRIMP U–Pb ages have been obtained for zircon in granitic gneisses from the aureole of the Rogaland anorthosite–norite intrusive complex, both from the ultrahigh temperature (UHT; >900 °C pigeonite‐in) zone and from outside the hypersthene‐in isograd. Magmatic and metamorphic segments of composite zircon were characterised on the basis of electron backscattered electron and cathodoluminescence images plus trace element analysis. A sample from outside the UHT zone has magmatic cores with an age of 1034 ± 7 Ma (2σ, n = 8) and 1052 ± 5 Ma (1σ, n = 1) overgrown by M1 metamorphic rims giving ages between 1020 ± 7 and 1007 ± 5 Ma. In contrast, samples from the UHT zone exhibit four major age groups: (1) magmatic cores yielding ages over 1500 Ma (2) magmatic cores giving ages of 1034 ± 13 Ma (2σ, n = 4) and 1056 ± 10 Ma (1σ, n = 1) (3) metamorphic overgrowths ranging in age between 1017 ± 6 Ma and 992 ± 7 Ma (1σ) corresponding to the regional M1 Sveconorwegian granulite facies metamorphism, and (4) overgrowths corresponding to M2 UHT contact metamorphism giving values of 922 ± 14 Ma (2σ, n = 6). Recrystallized areas in zircon from both areas define a further age group at 974 ± 13 Ma (2σ, n = 4). This study presents the first evidence from Rogaland for new growth of zircon resulting from UHT contact metamorphism. More importantly, it shows the survival of magmatic and regional metamorphic zircon relics in rocks that experienced a thermal overprint of c. 950 °C for at least 1 Myr. Magmatic and different metamorphic zones in the same zircon are sharply bounded and preserve original crystallization age information, a result inconsistent with some experimental data on Pb diffusion in zircon which predict measurable Pb diffusion under such conditions. The implication is that resetting of zircon ages by diffusion during M2 was negligible in these dry granulite facies rocks. Imaging and Th/U–Y systematics indicate that the main processes affecting zircon were dissolution‐reprecipitation in a closed system and solid‐state recrystallization during and soon after M1.
Petrogenetic significance of orthopyroxene‐free garnet + clinopyroxene + plagioclase ± quartz‐bearing metabasites with respect to the amphibolite and granulite facies
Authors: Pattison D. R. M. 
Published: March 2003

AbstractOrthopyroxene‐free garnet + clinopyroxene + plagioclase ± quartz‐bearing mineral assemblages represent the paragenetic link between plagioclase‐free eclogite facies metabasites and orthopyroxene‐bearing granulite facies metabasites. Although these assemblages are most commonly developed under P–T conditions consistent with high pressure granulite facies, they sometimes occur at lower grade in the amphibolite facies. Thus, these assemblages are characteristic but not definitive of high pressure granulite facies. Compositional factors favouring their development at amphibolite grade include Fe‐rich mineral compositions, Ca‐rich garnet and plagioclase, and Ti‐poor hornblende. The generalized reaction that accounts for the prograde development of garnet + clinopyroxene + plagioclase ± quartz from a hornblende + plagioclase + quartz‐bearing (amphibolite) precursor is Hbl + Pl + Qtz=Grt + Cpx + liquid or vapour, depending on whether the reaction occurs above or below the solidus. There are significant discrepancies between experimental and natural constraints on the P–T conditions of orthopyroxene‐free garnet + clinopyroxene + plagioclase ± quartz‐bearing mineral assemblages and therefore on the P–T position of this reaction. Semi‐quantitative thermodynamic modelling of this reaction is hampered by the lack of a melt model and gives results that are only moderately successful in rationalizing the natural and experimental data.
Strategy for Maximizing the Use of Arteriovenous Fistulae
Authors: Beathard Gerald A. 
Published: March 2003

ABSTRACTIncreasing the use of arteriovenous fistulae in dialysis patients requires a specific strategy. In order to properly select patients for an arteriovenous fistula (AVF), it is essential that the nephrologist become knowledgeable about the subject and that an organized approach be followed. Both the arterial and venous systems must be evaluated. Evaluation of medical history, general physical examination, specific physical examination related to the vasculature of the extremity, vein mapping and duplex ultrasound studies are all important. It is very important to assess the size of the vessels involved. Although a newly created AVF should be allowed to fully mature prior to use, failure to develop should be evaluated early. Many cases of early failure can be successfully salvaged. Even if the patient has an arteriovenous graft, they should be evaluated at the time of every graft failure for the possibilities of creating a secondary AVF.
Coordination of Care in Disease Management: Opportunities and Financial Issues
Authors: Mosley Coleman 
Published: March 2003

ABSTRACTPatients with end‐stage renal disease (ESRD) and pre‐ESRD require higher utilization of health care resources. Current reimbursement modalities contribute to the fragmentation of care, and inadequate financial information obscures the fiscal impact disease management's coordination of care can have for this population. Ignoring the extreme costs of the first 3 months of hemodialysis underestimates costs by as much as 16%. Potential areas of coordination and the financial benefits are discussed.In each venue of the care settings of a patient with chronic renal failure (CRF) they may receive excellent service. Too often there is not optimal coordination of care between these venues, and in fact the fragmentation of care can cause unnecessary wear and tear on the patient, and increases the overall expense to a health care system. Understanding sources of fragmentation, reimbursement effects, and potential corrections will enhance the patient's voyage through the system. This article provides some examples of the discoordination that presently exists and financial implications especially during the transition onto dialysis.In patients with end‐stage renal disease (ESRD), each arena of care has criteria established to quantitate quality. None of the settings, whether it is the dialysis unit, the hospital, the skilled nursing facility, or the physician's office, exists in the absence of regulations. These may be state or federal, National Council on Quality Assurance (NCQA), Health Plan Employer Data and Information Set (HEDIS), water standards, Occupational Safety and Health Administration (OSHA), fire codes, physician peer review, Medicare billing, Health Care Finance Administration (HCFA), the ESRD networks, credentialing, health maintenance organization (HMO) insurance requirements, pharmacy benefits and formularies, safe harbors, “antikickback,” or National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF‐DOQI) guidelines. For all the providers of care, the other critical component is the ability to have adequate income to stay in business, and make a profit. Each becomes very astute at working within the confines of the regulatory restrictions to provide good care. However, the continuity of care cannot be the overwhelming issue for many of the providers. The only person that is involved in every arena is the patient. The only provider that currently crosses over most arenas is the nephrologist. But the other element that exists in each arena is a payer.
Quantitative Characterization of Hemodialyzer Solute and Water Transport
Authors: Clark William R. 
Published: March 2003

ABSTRACTClinicians are frequently faced with the task of selecting a hemodialyzer for a dialysis‐dependent patient. Several quantitative dialyzer parameters, such as clearance, sieving coefficients, and ultrafiltration coefficient, are routinely used in this selection process. However, the quantitative basis and exact meaning of these indices are often unclear or misinterpreted. The purpose of this article is to provide a detailed description of several of these parameters with the hope that this information will enable clinicians to make dialyzer selection from a more quantitative perspective.