bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ocular complications in young patients with insulin dependent diabetes
Authors: North R. V. , Farrell U. , Banford D. , Jones C. , Gregory J. , Butler G. , Owens D. R. 
Published: March 2003

Purpose: To compare the visual functions of a group of young patients with insulin dependent diabetes mellitus (IDDM) to a control group, and identify those with retinopathy and assess the influence of metabolic control.Methods: A group of IDDMs (aged 10–21 years), were examined for two years at the UHW (n = 123). Fundus photography and ophthalmoscopy were performed under mydriasis. Visual acuity, colour vision (desaturated D15), contrast sensitivity (Vistech VCTS 6500) and metabolic control were assessed. In a subgroup (n = 7), accommodation, macular threshold, central visual fields and dark adaptation were measured.Results: IDDMs made significantly more errors with the desaturated D15 than the control group, and had higher macular thresholds and lower amplitudes of accommodation (P < 0.05). IDDMs with retinopathy had significantly poorer metabolic control (HbA1) than those without.Conclusion: Colour vision differed significantly between IDDMs and the control group. Fifty‐two IDDMs exhibited diabetic retinopathy. The need for good metabolic control is demonstrated.
The reliability of subjective refraction
Authors: Strang Niall C. , Winn Barry , Gray Lyle S. , Pugh John R. 
Published: March 2003

Purpose: In this study we investigate the accuracy of automated infrared autorefractors and determine whether spectacles can be prescribed on the basis of autorefractor results alone.Method: Two hundred and sixty two subjects (age range 7–92 years), participated in the study. All subjects underwent a complete eye examination and had their prescription determined by six commercially‐available autorefractors. A subsample of 47 subjects were randomly allocated spectacles using either the optometrist's or the autorefractor prescription in a double‐blind protocol. Subjects wore each prescription for two weeks and completed an oral questionnaire following each session.Results: All autorefractors showed a similar level of accuracy. The mean difference in one autorefractor between the sphere result and the subjective sphere was −0.03 DS (95% confidence limits ± 1.22 D). Cylindrical components revealed a smaller level of agreement. Autorefractor performance was not significantly affected by age or refractive error. The subjects who participated in the questionnaire preferred wearing the optometrist's prescription in 51% of cases and 21% of subjects were unable to adapt to wearing the autorefractor result.Conclusions: There is little difference in the accuracy of the six autorefractors. However, the 95% confidence limits of the instruments are too large to allow spectacles to be prescribed directly from the results of automated refraction.
Theoretical predictions and experimental findings of visual deficits in glaucoma
Authors: Sahraie A. , Edgar D. F. , Barbur J. L. 
Published: March 2003

Purpose: To investigate the motion and colour processing in normal subjects and in patients with primary open angle glaucoma, and to develop theoretical models in order to explain present findings and to understand the processes involved.Methods: Movement processing was investigated using an optical motion projection system, capable of generating continuous motion of a single dot target with controlled speed, displacement and motion direction. Displacement and direction discrimination thresholds (i.e. target displacement at a constant speed needed for 75% probability of detection of motion or correct discrimination of its direction) were measured for both foveal and peripheral stimulus presentations and for a range of speeds. Colour vision was tested using a novel method which employs a random luminance modulation technique to mask out achromatic contrast changes and allowing detection of a spatially structured object based on the processing of chromatic signals only (Barbur et al. 1993).Results: Changes in the parameters of the motion detection model (e.g., delay time and receptor regularity) that was developed to predict the experimental data in normal subjects also predicts an increase in displacement threshold and poorer sensitivity for discrimination of motion direction in glaucoma patients. The results obtained show that patients may report stimulus motion in 80% of presentations whilst performing at chance when required to discriminate the direction of motion. Chromatic discrimination ellipses measured for foveal stimulus presentations in glaucoma patients were often similar to those measured in normal subjects. In the periphery, however, much larger chromatic displacement thresholds were measured in all directions.Conclusions: The technique used to measure the chromatic discrimination ellipses is sensitive to glaucomatous nerve damage and the results suggest a larger threshold elevation in the periphery than at the fovea. The motion model developed to explain performance in normal vision also predicts the experimental findings in glaucoma patients and may be used to predict degraded motion discrimination in patient groups with similar pathologies.
The flash VEP in term and preterm infants: effect of flash intensity and sleep state
Authors: Shepherd Ashley J. , Saunders Kathryn J. , McCulloch Daphne L. 
Published: March 2003

Purpose: The flash visually evoked potential (VEP) may be a useful indicator of visual and/or neurological prognosis following premature birth. A range of flash intensities was used to investigate maturation of the visual pathway in preterm infants.Methods: Subjects were a consecutive group of 20 healthy preterm infants born at under 35 weeks gestation (29–35 weeks). VEPs in response to two flash intensities were recorded at 3 days of age and at term age (ISCEV standard protocol). The infant's sleep state was recorded for each test.Results: Flash VEPs were consistently recordable in preterm infants. The most prominent component was a simple negativity (N3) approximately 300 ms after the flash. Its position and amplitude were unaffected by flash intensity, state or age (ANOVA). By term age, the P2 was the prominent component of the flash VEP. Its amplitude increased significantly with flash intensity (P < 0.01 repeat measures ANOVA) but its latency was unaffected.Conclusions: The flash VEP between 29 and 35 weeks gestation is relatively invariant and shows little or no effect of stimulus intensity. In contrast, flash VEPs in term age infants have a P2 component which reflects stimulus brightness and sleep state.Funded by The Scottish Office, Department of Home and Health.
The use of Newton's rings for characterising ophthalmic lenses
Authors: Illueca C. , Vazquez C. , Hernández C. , Viqueira V. 
Published: March 2003

SummaryThe interference technique of Newton's Rings is widely used for the quality control of optical surfaces because the precision obtained with this method proves to be very satisfactory. The dimensions of the rings permits calculation of the radii of curvature of the analysed surfaces and deformation of the interference pattern can be utilised to calculate other parameters, such as astigmatism. We describe the study of progressive surfaces by means of this technique, whereby the analysis of the various points of the progressive corridor is made, and also include information on the power function for these lenses, as well as the addition and corridor length.
Tear break‐up time: clinical procedures and their effects
Authors: Cho Pauline , Leung Lawrence , Lam Ada , Choi Alex 
Published: March 2003

SummaryThree successive (representative) values of fluorescein‐instillation TBUT (tear break‐up time) were obtained from a group of young Hong Kong (HK)‐Chinese. The median TBUT1, TBUT2 and TBUT3 were 3.2, 3.8 and 4.5 sec, respectively. Wilcoxon signed‐rank tests showed that TBUT1 was significantly different from TBUT2 and TBUT3, but there was no difference between TBUT2 and TBUT3. It is therefore important, when measuring the TBUT, to specify which TBUT value was taken as the representative TBUT. Fluorescein was reapplied about six min after the first application, and the TBUT value re‐determined (TBUTR). The median TBUTR was not significantly different from TBUT1. The subjects were requested to return another day and TBUT values (TBUTW) were determined, with the subjects opening their eyes as wide as possible, such that the palpebral aperture size was increased. The mean±SD normal palpebral aperture size was 10.0±1.3 mm, and the mean±SD palpebral aperture size with the eyes wide open was 11.4±1.5 mm. The median TBUTW (3.6 sec) was significantly longer than the median TBUT1 (3.0 sec), but this difference appeared to be due to the extremely long TBUTW of one subject; no significant difference was found between the median TBUTW (3.4 sec) and TBUT1 (2.8 sec) when data from this subject were excluded. There was no significant correlation between changes in palpebral size and TBUT value.
Sequential pattern‐onset, ‐reversal and ‐offset VEPs: comparison of effects of checksize
Authors: Shawkat Fatima S. , Kriss Anthony 
Published: March 2003

SummaryThe effects of checksize on individual components of half‐field pattern‐onset, ‐reversal and ‐offset VEPs were studied by presenting these three modes of stimulation sequentially in a single recording epoch so as to provide near identical recording and subject conditions. Components on the side of the scalp ipsilateral and contralateral to the stimulated half‐field were measured so as to separate the macular and paramacular contributions. Ten checksizes were used (6′–110′). MANOVA showed a significant effect of checksize: small checksizes enhanced onset ipsilateral CII and contralateral P105, as well as all ipsilateral reversal components and offset N85 component, suggesting they are reflecting macular function. Onset CI, and contralateral reversal N105 and offset N115 components increased in amplitude with increasing checksize, suggesting they are predominantly of paramacular origin. The morphology of the contralateral onset P105 component was checksize dependent: small checks (<35′) produced a sharply defined positivity (macular sub‐component), whereas larger checks produced a broadened/bifid waveform, suggesting the emergence of a later paramacular sub‐component.
Evaluation of the pinhole pupillometer
Authors: German Emma J. , Hurst Mark A. , Wood Diana 
Published: March 2003

SummaryEvaluation of pupil diameter is used in many clinical and research fields to aid diagnosis of neurological disorders and to monitor pharmacological effects upon the eye. Methods used to determine pupillary diameter have evolved from simple scale measurements to much more complex systems, supposedly improving accuracy and repeatability. However, many techniques are restricted to the consulting room or research laboratory due to the size of the equipment, its cost, or the expertise required.We have evaluated a portable pupillometer originally developed by Broca, capable of precise measurements on fixed, dilated pupils, that has the potential to be used by unsupervised patients. Luminance levels will still need to be controlled because, although luminance does not influence the mechanics of the pupillometer itself, it significantly affects the natural pupil. The pinhole size should ideally be 1.1 mm in diameter, since smaller pinholes underestimate and larger holes overestimate pupil size. The pupillometer also exhibited reasonable accuracy in fixed pupils dilated with tropicamide. Pupil measurements were overestimated by 0.5% using the 1.1 mm pinholes (insignificant if the pupil can be measured to the nearest 0.25 mm) and both intra‐ and inter‐visit repeatabilities were relatively good. The results from this study therefore indicate that the pinhole pupillometer may be of use in pupil research, since it facilitates more frequent pupillary measurements over much longer time intervals than are currently achievable.
The stenopaeic slit: an analytical expression to quantify its optical effects in front of an astigmatic eye
Authors: Escrivá L. Muñoz‐ , Furlan Walter D. 
Published: March 2003

SummaryThe stenopaeic slit is a trial case accessory used in subjective refraction, especially when high astigmatism is present. In spite of its simplicity, the effect of the slit when it is not oriented along one of the principal meridians of the examined eye is difficult to predict, even in terms of classical geometrical optics. In this paper, the optical principles of the slit are considered with full details in the theoretical framework of the dioptric power space. An analytical expression to obtain the residual refractive error when a stenopaeic slit is placed in front of an astigmatic eye at any orientation is deduced. In the light of these results, some aspects of the clinical procedure are discussed.
The gradient index and spherical aberration of the lens of the human eye
Authors: Smith George , Atchison David A. 
Published: March 2003

SummaryWe present equations for analysing the primary spherical aberration of the crystalline lens, both as a whole and of its contributing parts. We apply these equations to two examples of gradient index lenses. The spherical aberration of one lens is well outside that expected for real lenses, but that of the other is within this range. We assess the sensitivity of the aberration to changes in surface shape and gradient index distribution. The process is applicable to other models of the gradient index of the lens.
Accommodation and the Stiles–Crawford effect: theory and a case study
Authors: Kruger P. B. , López‐Gil N. , Stark L. R. 
Published: March 2003

Summary Purpose:
Fincham (The accommodation reflex and its stimulus.
Br. J. Ophthalmol.
35, 381–393) was the first to suggest that the Stiles–Crawford effect (Type I) might provide a stimulus for accommodation, but the possibility has not been investigated experimentally. The present paper outlines a theoretical basis for such a mechanism, and includes a case study on a subject with a nasally decentred Stiles–Crawford (S–C) function. Methods: Accommodation to a monochromatic sine grating was monitored continuously with the natural S–C function intact, or with apodising filters imaged in the subject's pupil to neutralise, reverse or double the natural S–C function. Results: Mean accommodative gain was not reduced significantly when the normal S–C function was either neutralised or reversed. Conclusions: For the present subject, the average S–C effect does not mediate the accommodation response to defocus, but more subjects should be examined. Other methods by which directionally sensitive cone receptors could detect light vergence are discussed.
Nutritional and Medical Assessment and Management of Eating Disorders
Authors: Rock Cheryl L. 
Published: March 2003

AbstractPatients with eating disorders have abnormal eating patterns and altered nutritional status, in addition to dysfunctional attitudes and perceptions regarding food and body weight. The prevalence of clinical eating disorders in the general population is estimated to be 0.5–1% for anorexia nervosa, 2% for bulimia nervosa, and 2% for binge eating disorder. Both genetic and environmental factors appear to contribute to the risk of developing an eating disorder, which is often perpetuated by poor nutritional status and chaotic eating patterns. Metabolic, nutritional, and clinical abnormalities in both anorexia nervosa and bulimia nervosa occur as a result of starvation and purging behaviors. The primary goal of nutrition intervention in anorexia nervosa is weight restoration, which is also a crucial factor in the prevention of irreversibly compromised bone density. The primary goal of nutritional management of bulimia nervosa is to normalize the patient's eating pattern, which is typically chaotic and characterized by an overall pattern of food rules, restrictions, or dieting, regularly interspersed with episodes of binge eating and purging. Patients with an eating disorder not otherwise specified can have serious eating problems that can adversely affect health status, and the management issues in these patients are similar to those in the patient with anorexia nervosa or bulimia nervosa. Results from long‐term outcome studies suggest that the majority of patients with eating disorders make a full recovery, despite the severity of the disturbances in eating patterns and nutritional status present at diagnosis.
The Effect of Alcohol on Blood Pressure
Authors: Suter Paolo M. , Vetter Wilhelm 
Published: March 2003

AbstractThe pathogenesis of hypertension, a major risk factor for cardiovascular disease, is multifactorial. Alcohol consumption has been identified as one important modulator of blood pressure; many epidemiological, clinical, and interventional studies have shown a linear relationship between alcohol intake and blood pressure. These studies have also found that the absolute amount of alcohol consumed is more significant than the beverage type; recent alcohol intake is more influential than past alcohol intake; the hypertensive effect of alcohol is more pronounced in frequent drinkers and in females; and upon cessation or reduction of alcohol intake, blood pressure declines. Many different mechanisms, including alcohol's effects on the central nervous system and the vessel wall, may be responsible; however, a single mechanism has yet to be identified. Any patient with resistant hypertension without secondary hypertension should reduce alcohol intake as a nonpharmacological strategy to lower blood pressure. Daily consumption should be avoided and the upper limit of alcohol intake in one day should be 20 g (0.7 fluid ounce) for women and 30 g (1 fluid ounce) for men. Whenever possible, alcohol should be consumed with food.
Mind/Body Medicine: An Introduction for the Generalist Physician and Nutritionist
Authors: Johnson Susan Slager , Kushner Robert F. 
Published: March 2003

AbstractScientific evidence from psychoneuroimmunology (PNI) is driving a paradigm shift from a model of biomedical medicine to a biopsychosocial/spiritual model of mind/body medicine. Mind/body medicine seeks to bring balance to all disparate aspects of mind, body, and spirit, thus strengthening patients' potential for total wellness. In this model, nutrition is viewed as one means of boosting the intrinsic capacity for preventing illness and attaining wellness. Accumulating evidence for links among stress, unhealthy lifestyles, and obesity support the use of mind/body therapies to counter negative effects of stress in the context of an overall approach to this condition. This paper discusses evidence and clinical applications for the healing potential of autogenic training, breathing practices, guided imagery, meditation, music therapy, and spirituality.
Clinical Implications of Vitamin B12 Deficiency in the Elderly
Authors: Russell Robert M. , Baik Hyun Wook 
Published: March 2003

Abstract Vitamin B12 deficiency is a prevalent condition in the elderly. Depending on the diagnostic criteria used, more than 10% to 15% of people over the age of 60 are estimated to be deficient in vitamin B12.Diagnosis can be problematic because vitamin B12 deficiency may present as neurological or mental‐status changes—which can be confused with symptoms of other age‐related neurological disorders—rather than as megaloblastic anemia. A higher folate intake, due to the fortification of flour with this B vitamin, can mask and/or precipitate the hematologic signs of vitamin B12 deficiency, potentially delaying diagnosis and treatment, and increasing the risk of irreversible neurological damage to elderly people with subtle vitamin B12 deficiency. This paper will discuss two conditions contributing to the high prevalence of vitamin B12 deficiency in the elderly, as well as approaches to its diagnosis and treatment.
δ18O and yttrium zoning in garnet: time markers for fluid flow?
Authors: Skelton A. , Annersten H. , Valley J. 
Published: March 2003

AbstractThe relative timing of two discrete pulses of metamorphic fluid flow is constrained based on chemical zoning in several garnet crystals from Kvaløya, Troms, northern Norway. The garnet crystals measured 1–2 cm in diameter and were contained within c. 1.6 Ga, staurolite grade metasediments. Major element zoning indicates that garnet grew under normal prograde conditions in the garnet and/or staurolite zones.Timing constraints are based on comparisons between major and trace element chemical zoning, oxygen isotope (δ18O) zoning and deformational (inclusion trail) zoning in one of the garnet. We interpret at least two pulses of metamorphic fluid flow. The first pulse occurred during the syn‐tectonic growth interval. The δ18O zoning was reversed relative to ‘normal’ prograde zoning and the δ18O maximum was located within the syn‐tectonic growth zone, displaced 3–4 mm from the garnet core. The fluid might have been sourced in neighbouring calcareous pelites and may also have caused formation of an Y ring. The second (and subsequent) pulse(s) occurred during/after the post‐tectonic growth interval. δ18O was locally increased at the garnet rim, particularly where the rim was sheared. The incomplete rim was also enriched in calcium. Transport of oxygen and calcium by metamorphic fluids is well documented. Transport of Y is both problematic and poorly understood, but might have been facilitated by complexing with F and/or CO2.
Thermal modelling in shallow subduction: an application to low P/T metamorphism of the Cretaceous Shimanto Accretionary Complex, Japan
Authors: Miyazaki K. , Okumura K. 
Published: March 2003

AbstractThis paper presents the results of numerical modelling to investigate the regional occurrence of prehnite‐bearing metamorphic rocks at shallow levels in subduction zones. The modelling assumes a simple geometrical configuration in which the thermal structure in a prism is controlled by boundary conditions at the top and base of the prism. It is expected that the predominant metamorphic facies in a prism will change with decreasing age of the descending slab. The results of thermal modelling show that the facies boundary between pumpellyite–actinolite and prehnite–actinolite facies (including prehnite–pumpellyite facies) overlaps with an array of P–T conditions in the prism when the age of a descending slab is younger than 10 Myr. This implies that the change of the predominant metamorphic facies from pumpellyite–actinolite to prehnite–actinolite facies will switch drastically. The critical age of the switch depends on subduction parameters. In particular, the critical age of the descending slab is <5 Myr in the case of no shear heating, with a subduction rate of v=75–200 mm y−1 and subduction angle of θ=5–15°. For shear heating (constant shear stress=30 MPa) with a subduction rate of v=75 mm y−1 and subduction angle of θ=10° the critical age is 7 Myr. To test this switching behaviour in the development of prehnite–actinolite facies in the prism, petrologic data from the Cretaceous Shimanto Accretionary Complex (CSAC) in Kyushu, Japan were compiled. The regional occurrence and mineral assemblages of prehnite‐bearing metamorphic rocks suggest that the most of CSAC was metamorphosed under prehnite–actinolite facies. This conclusion is consistent with subduction of a young, hot slab, as has been proposed based on other geological observations. This suggests that the regional extent of the prehnite–actinolite facies metamorphic rocks may be a unique evidence for the subduction of a young, hot slab.