bluuebunny/crossref_metadata_2025_split huggingface dataset:
The significance of ultraviolet radiation for eye diseases. A review with comments on the efficacy of UV‐blocking contact lenses
Authors: Bergmanson J. P. G. , Söderberg P. G. 
Published: March 2003

SummaryAcute and cumulative ultraviolet radiation (UVR) exposure has been proposed as an important causative factor in the development of a whole spectrum of eye diseases. The present review examines the scientific evidence for and against such an association, with special emphasis on recent additions to the literature. The sun is the main UVR source on earth, and it is beyond scientific doubt that the cornea can be harmed by both acute and cumulative ambient exposures. There is also powerful epidemiological support for an association between chronic UVR exposure and the formation of cataracts and pterygia. The evidence in support of UVR linkage to pinguecula, ocular neoplasms and retinal changes is weaker‐in part because there are fewer studies reported in the literature. It is concluded that UVR‐blocking hydrogel contact lenses and spectacles are two equally effective preventive measures in minimizing unnecessary suffering and health costs, especially for people who spend a significant time outdoors and for those who live in more UV intense environments. UVR‐blocking contact lenses and spectacles must not, however, be substitutes in situations that require UVR‐blocking safety goggles.
Contrast sensitivity after wearing prisms to correct for heterophoria
Authors: Methling Dieter , Jaschinski Wolfgang 
Published: March 2003

SummaryContrast sensitivity to sinusoidal gratings was measured at spatial frequencies of 1.5–16 c/deg in 8 subjects before and after wearing prisms (for at least two weeks) to correct heterophoria, prescribed by the full correction method of H.‐J. Haase (Binocular testing and distance correction with the Berlin Polatest [trans. W. Baldwin]. J. Am. Optom. Assoc. 34, 115–125, 1962). At higher spatial frequencies of 12–16 c/deg, we found an average improvement in contrast sensitivity of 0.15 log unit. This effect is estimated to correspond to an increase in visual acuity of 15%.
Microfluctuations of steady‐state accommodation measured with ultrasonography
Authors: van der Heijde G. L. , Beers A. P. A. , Dubbelman M. 
Published: March 2003

SummaryOver the past 30 years investigators have noted fluctuations in accommodation when the eye views a stationary target. These microfluctuations have been studied mainly with the use of infrared optometers. Two dominant components have been found: a low frequency component (LFC; 0.05–0.5 Hz) and a high frequency component (HFC; 1.0–2.2 Hz). The LFC probably has a neurological origin. The HFC is supposed to be related to the arterial pulse. The aim of this study was to investigate accommodative fluctuations and gain more information about their origin by using a non‐optical method. We used continuous ultrasonographic biometry to measure changes in anterior chamber (AC) depth, lens thickness and vitreous length during steady‐state accommodation. Simultaneously, the electrocardiogram (ECG) was recorded. Changes in axial length were calculated offline by taking the sum of the changes in the three intraocular distances. Results show that fluctuations with an LFC were present in all three intraocular distances but not in the axial length, proving that only the lens was involved. In contrast with the findings of investigators using optical methods, no HFC was present in fluctuations of AC depth and lens thickness. However, a small HFC was found in registrations of the vitreous and axial length, which appeared to correspond with the heart rate.
Visibility of motion in infant vernier displays, using adult subjects
Authors: Carkeet A. , Levi D. M. , Manny R. E. 
Published: March 2003

SummaryMotion is frequently incorporated in stimuli used for psychophysical testing of vernier acuity in infants and young children. In such stimuli, detection of the vernier offset is necessary in order to perceive the motion. Research described in this report tested whether the perception of a vernier offset is sufficient to signal the stimulus motion in adults. We measured how motion detectability changed as a function of vernier offset for two adult subjects, using a stimulus similar to that employed by other authors to measure vernier acuity in infants and children. Motion visibility varied with offset size, achieving a detectability of motion (d′) of 0.95 (comparable to two‐alternative forced‐choice thresholds) at stimulus offsets of 16–19 s arc. In comparison to the motion, the stimulus offset itself was much easier to see, being detectable on 95–100% of trials with the smallest offset, 6.6 s arc. This distinction, between the visibility of motion and the visibility of the vernier offset itself, should be considered when interpreting vernier results using such displays, especially in infants and children for whom motion may be the attractive cue.
Calibration and validity of an eccentric photorefractor
Authors: Chan Osbert Y. C. , Edwards Marion , Brown Brian 
Published: March 2003

SummaryA new graphical calibration method was developed to convert the photorefractive reflex into refractive error. With this graphical method, the refractive error can be obtained for pupil sizes and for photorefractive reflex sizes which have not been precalibrated. In the conventional method, the refractive error associated with non‐precalibrated pupil and reflex sizes is obtained by interpolating between neighbouring precalibrated points. This introduces error because the relationship between refractive error and pupil and reflex size is not linear. Three hundred and sixty‐one children aged between 36 and 65 months were clinically examined and photorefracted. The refractive error obtained using retinoscopy and the eccentric photorefractor agreed well with each other, although the photorefractor tended to under‐estimate refractive error. Using the referral criteria developed by Chan, O. Y. C. and Edwards, L. M. (Refraction referral criteria for Hong Kong Chinese Children. Ophthal. Physiol. Opt. 14, 259–256, 1994), the photorefractor had a sensitivity of 74.6% and a specificity of 96.4%. All the under‐referred cases were borderline, having just failed the referral criteria. All the cases with hyperopia of > + 2.0 D, astigmatism of > 1.25 D and visual acuity of worse than 6/18 were identified.
Weber's law for position is incidental rather than fundamental
Authors: Latham Keziah , Whitaker David 
Published: March 2003

Purpose: Weber's law for position states that the minimum discriminable change in separation between two objects is proportional to the separation itself. This study aimed to disentangle the individual effects of separation, eccentricity and spatial scale in determining Weber's law for position.Methods: Spatial interval discrimination thresholds were measured for two Gabor patches at twice contrast detection threshold. The patches varied in spatial scale (blur parameter of the patch), eccentricity (using isoeccentric arcs of different radii), and separation (varied by moving the patches around the isoeccentric arc). The effect of contrast on thresholds was also examined.Results: Weber's law holds for geometrically similar stimuli, i.e. stimuli with a constant separation/eccentricity ratio, over a range of spatial scales and eccentricities. Thresholds are contrast dependent at small geometric ratios, and contrast‐independent at large ratios. The Weber fraction is optimum (4%) for fovea‐centred stimuli, and is contrast dependent at smaller geometric ratios, becoming smaller at higher contrasts.Conclusions: Weber's law is observed at large geometric ratios because thresholds are proportional to eccentricity. At small geometric ratios, thresholds show a greater dependence on separation which increases with increasing contrast. Weber's law arises not from a single fundamental process, but from both increasing separation and increasing eccentricity, regardless of spatial scale.
The relative sensitivity of visual acuity and small letter contrast sensitivity in early cataract
Authors: Elliot David B. , Situ Ping 
Published: March 2003

Purpose: To investigate the effects of early cataract on spatial frequency dependent contrast sensitivity (CS) measurement and log MAR visual acuity (VA) assessment.Methods: The relative sensitivity of two computer‐generated letter CS tests, 1/9.5 letter CS (1/9.5 LCS) (assessing low to medium spatial frequency CS) and 6/9.5 letter CS (6/9.5 LCS) (measuring high spatial frequencies), and a log MAR VA test were evaluated in 19 subjects with early cataract and 21 age‐matched controls.Results: Results indicate that these three tests decline with increasing cataract formation. The greatest visual reduction and the highest test discriminative ability were found with the 6/9.5 LCS test (Az score of 0.441 versus 0.408 for VA) and the lowest with the 1/9.5 LCS test (Az score of 0.383). However, measurement variability was greatest for 6/9.5 LCS. After correcting for this variability, the 6/9.5 LCS test still proved slightly more sensitive to early cataract and cataractous change than the other two measurements.Conclusion: The study suggests that 6/9.5 LCS or other size small letter CS tests are able to detect more subtle vision loss in cataract than visual acuity.
Visual development in infants and young children with Down's syndrome
Authors: Woodhouse J. Margaret , Pakeman Valerie H. , Parker Margaret , Cregg Mary , Fraser William I. , Lobo Sandra , Sastry Prema 
Published: March 2003

Purpose: Ocular and refractive defects are common amongst people with Down's syndrome. We are conducting a long‐term study of the development of refraction, accommodation and acuity in infants with Down's syndrome, from 12 weeks of age, in order to identify age of onset and possible consequences of such defects.Methods: To date, 54 children have entered the study. All measurements are made during home visits, and comprise Mohindra and dynamic retinoscopy, and Preferential Looking.Results: Cross‐sectional data suggest that acuity lies within normal ranges in infancy, and falls behind the norms only from the age of 2 years. Refractive errors in the general population decrease in infancy (the process of emmetropisation). Our data show that the opposite happens in children with Down's syndrome. The prevalence of refractive errors is higher in the preschool and school‐age children, than amongst the infants. Accommodation is defective from the earliest age of testing. Infants and young children with Down's syndrome consistently under‐accommodate to near targets, even when visual acuity and refractive errors are normal.Conclusions: The implication of accommodative dysfunction on emmetropisation is considered, and the possible association between visual and cognitive development explored.
The effect of abnormal eye movements upon visual acuity
Authors: Simmers Anita J. , Gray Lyle S. , Winn Barry 
Published: March 2003

Purpose: Abnormal fixational eye movements such as those which occur in nystagmus can have a deleterious effect upon visual acuity measurement which is difficult to determine. The repeat letter format of the Regan Repeat Letter charts (RRL) is designed to measure visual acuity independently of abnormal eye movements, and should give higher visual acuity scores than linear test charts in subjects with fixational instability. In the present study RRL and Glasgow Acuity Cards (GAC) were used to determine visual acuity losses arising from fixational instability.Methods: Monocular visual acuity was measured in five subjects with congenital nystagmus using both GAC and RRL while eye movements were continuously recorded using an infrared limbal reflection eyetracker.Results: Mean visual acuity obtained with RRL was significantly higher (P < 0.01) than that obtained with GAC. A significant correlation (P < 0.01) was observed between the amplitude of the nystagmus and the visual acuity obtained using GAC. There was no significant correlation between the amplitude of the nystagmus and visual acuity measured using RRL.Conclusions: The results show that RRL can measure visual acuity independently of abnormal fixational eye movements. Fixational instability in nystagmus is a limiting factor in visual acuity measurements obtained using a linear test chart format.
Binocular vision in interceptive timing
Authors: Mon‐Williams Mark , Wann John P. , Rushton Simon 
Published: March 2003

Time to contact of an approaching object may be specified through monocular optic expansion, e.g. ‘tau’ (Lee, 1976). On the other hand it has been demonstrated that disturbing binocular information impairs performance in a dynamic interceptive task (Judge and Bradford, 1988).Three optical devices were employed to explore whether participants (n = 5) could be trained to utilise different information when estimating time to contact of an approaching ball. A pendulum was used to project a ball at three different velocities. Performance was measured using an IR‐based tracking system (Selspot), and an IR eye‐tracker (Ober2) was used to monitor vergence. Cyclopean spectacles (which remove disparity information) were used to train participants. Pre‐ and post‐training performance was compared with performance in telestereoscopes (these double binocular disparity at near), and spectacles that control for secondary optical effects by increasing the optical pathlength and reducing the field of view and illumination.Our results confirm that disrupting binocular information impairs performance but that performance quickly recovers. Reasons for the performance recovery will be discussed in relation to the use of available optical information.
The analysis of the transient PERGs to contrast variation
Authors: Lu W. , Harding G. F. A. 
Published: March 2003

Black and white checkerboards (56′) of varying contrast levels were presented in the transient reversal mode (2 Hz). The transient Pattern Electroretinograms were recorded on four subjects with normal vision using DTL fibres. Across the contrast range 9–80%, the amplitudes of the response were linearly sensitive to contrast variation without saturation (P < 0.001). Two potentials on the major negative potential (N95) divided by a notch had different contrast sensitivities and contrast gains: the potential after the notch (a‐Nw) was strikingly less sensitive to contrast variation and had a lower contrast gain than the potential before the notch (Nw). a‐Nw had a linearity at contrast level over 23%. Nw showed a high similarity to P50 in both contrast versus amplitude function and contrast gain.The evident difference of the contrast gains between Nw and a‐Nw suggests that there are possibly some corresponding differences in their retinal origins. It is assumed that the major negative potential after the notch is functioned by the inner retinal neurones with low contrast sensitivity, which includes the ganglion cells, being possibly predominated by the retinal magnocellular cells; the potential Nw has some common retinal mechanisms with P50, probably representing the macular function.
Could a cycloplegic agent be replaced by a fogging or a corrective lens in the biometric measurement of the crystalline lens?
Authors: Kee C. S. , Do Tony C. W. , Lai Ricky Y. K. , Wong G. , Lam Andrew K. C. 
Published: March 2003

SummaryThis study investigated whether a fogging or a corrective lens could be used to replace a cycloplegic agent in the ultrasonic measurement of crystalline lens thickness in myopia. A group of 28 Hong Kong Chinese adults with myopia was recruited. The crystalline lens thickness of the examined eye was measured by A‐scan ultrasonography while the fixating eye was in one of three conditions: fog (+2.00 D fogging lens), full corrective lens, or cycloplegia (50 minutes after instillation of 1% cyclopentolate HCl). We found that the mean lens thickness was significantly different between the three conditions in our myopic subjects. The mean crystalline lens thickness under fogging and corrective lens conditions was significantly greater than the cycloplegic condition by 0.09 mm and 0.11 mm, respectively. The 95% limits of agreement compared to cycloplegia (fogging: −0.32 to +0.14; corrective: −0.35 to +0.13) showed marked intersubject variability, indicating that there is a risk of overestimating the lens thickness when substituting cycloplegia with either a fogging or a corrective lens.
Relationship between intraocular pressure and eye growth in chick
Authors: Schmid Katrina L. , Hills Tracy , Abbott Meredith , Humphries Michelle , Pyne Kylie , Wildsoet Christine F. 
Published: March 2003

AbstractIn infants, abnormally high intraocular pressure (IOP) results in excessive eye enlargement. In the study reported here, we investigated whether IOP might be a determinant of ocular elongation using the chick as an animal model. Specifically, we examined IOP changes in (I) normally developing eyes, and (II) eyes undergoing altered growth. In the first case (I), developmental changes in IOP, axial length and refractive error were assessed at approximately daily intervals during early development (days 2–11 post‐hatch, n = 8), and at weekly intervals from weeks 1 to 6 (n = 8). In the second case (II), opposite ocular growth responses were elicited using −15 D and +15 D defocusing spectacle lenses fitted monocularly to 8‐day‐old chicks (n = 8 and 7, respectively). Treated eyes were measured 3 and 7 h after lens application (between 9 and 10 am), as well as 1, 2 and 4 days later, around the same time as the initial lens application. In normal development (I), IOP increased over the first post‐hatch week, peaking at 18.0 ± 5.1 mmHg, and declined slowly thereafter to be back to near ‘hatching’ values at 6 weeks (12.7 ± 5.3 mmHg at day 2 cf. 13.4 ± 1.9 mmHg). Eyes elongated at an approximately linear rate over the entire monitoring period. The −15 D and +15 D lenses (II) produced opposing effects on eye growth, as indicated by axial length changes of + 0.67 ± 0.25 mm cf. −0.33 ± 0.17 mm over the 4‐day treatment period. Both groups showed decreases in IOP over the first 20 h of lens wear. The faster growing eyes of the −15 D group exhibited a later relative increase in IOP. The described changes in IOP are compatible with, but do not prove, a modulatory influence of IOP on early eye growth.
Vitamin K: A Practical Guide to the Dietary Management of Patients on Warfarin
Authors: Booth Sarah L. , Summa Maria A. 
Published: March 2003

Warfarin has been successfully used in the medical management of thromboembolic disease for nearly six decades. It is widely assumed that a dietary vitamin K–warfarin interaction exists. To avoid this potential interaction, patients typically receive instructions to consume a constant dietary intake of vitamin K, and sufficient data exist to suggest that a constant dietary intake of vitamin K that meets current dietary recommendations of 65 to 80 mg/day is the most acceptable practice for patients on warfarin therapy. Data concerning the vitamin K content of commonly consumed foods, however, are not readily accessible to clinicians and patients. An understanding of the dietary vitamin K‐warfarin interaction, and dietary sources and usual intakes of vitamin K may facilitate successful anticoagulation for patients being treated with warfarin. ▪
Key Words:
vitamin K, warfarin, anticoagulant phylliquinone
Nutrition in the Care of the Cancer Patient
Authors: Mutlu Ece A. , Mobarhan Sohrab 
Published: March 2003

AbstractProper nutrition care is essential to help prevent or minimize the deleterious effects of cancer, namely malnutrition and cachexia, on nutrition status. When designing appropriate nutrition support, clinicians should consider a patient's history and clinical state including extent of the disease, expected survival, psychological status, and current lifestyle. Oral nutrition is often the preferred means of feeding, but may be limited by factors related to the cancer, the treatment, and the psychologic issues surrounding this disease. Several strategies have been recommended to help patients achieve an adequate oral intake in the presence of anorexia. However, for patients who are severely malnourished or unable to consistently consume more than 75% of their energy needs, enteral nutrition may be indicated. Parenteral nutrition is appropriate only for certain subsets of cancer patients. Numerous trials have shown that use of the enteral route gives comparable results to the parenteral route and is associated with fewer complications and lower costs in both cancer and noncancer patients. There has been much recent interest in the use of immunotherapy—arginine, essential fatty acids, and glutamine—to improve the nutritional status of patients with cancer.
Exercise and HIV Infection
Authors: Roubenoff Ronenn 
Published: March 2003

AbstractHIV infection is characterized by two opposing macronutrient problems: wasting and lipodystrophy. Wasting is defined as the unintentional loss of 10% or more of body weight. Lipodystrophy is the loss of subcutanous fat in the legs, arms, and face, with increased deposition of fat in the abdomen, breasts, and upper back. In both cases, there is evidence that a judicious diet and exercise can help to reverse or ameliorate these abnormalities. This brief review outlines the current evidence that resistance exercise can be used to treat wasting, and that combined aerobic and resistance exercise can reduce abdominal fat gain in lipodystrophy.
Stages of Change in Clinical Nutrition Practice
Authors: Molaison Elaine Fontenot 
Published: March 2003

AbstractFor years, nutritionists have developed education materials that attempted to change dietary behaviors. However, most of these programs were effective only in increasing knowledge and did not produce long‐term behavior change. Research indicates that nutrition interventions will be more effective if based on a theoretical model. The stages of change theory attempts to explain behavior change as a series of levels of readiness to change. The stages range from precontemplation, where an individual does not recognize the need for change, to the maintenance of long‐term behavior change. Use of this theory in nutrition education has been found to be most effective if education methods are stage specific and address the individual needs of clients. Unfortunately, little research has been done using this theory in traditional clinical nutrition practice, but implementation may be easy for the nutritionist and may help to increase compliance with dietary recommendations in individuals with chronic disease. The first step in using the stages of change theory is to determine the behavior that is going to be changed. With this information, the clinician can then determine the patient's stage of readiness to change a variety of dietary habits. Through the identification of an individual's stage, education methods can be tailored to meet the needs of the patient, helping to promote life‐long dietary change.