Quantifying the vertical fusion range at four distances of fixation in a normal population.

Aim: To compare the vertical fusional amplitudes in isometropic participants with normal binocular single vision at four distances of fixation: 33 cm, 1 m, 4 m, 6 m. Methods: Vertical fusion ranges (break point and recovery point) were measured with a Gulden vertical prism bar with the participant fixing a 6/12 Snellen equivalent letter, twice at each distance. Order effects were controlled with randomisation of both fixation distance and prism direction. Results: Twenty-seven participants were examined (aged 20.4 ± 1.05 years). Base up and base down measurements were similar, therefore measurements were combined to give a total vertical range. Median values for the break points were: 33 cm, 6(Δ) ; 1 m, 6(Δ); 4 m, 5.5(Δ); 6 m, 5.5(Δ); and for the recovery points were: 33 cm, 4(Δ); 1 m, 4(Δ); 4 m, 3.5(Δ); 6 m, 3.5(Δ). The difference was significant between either of the near measures (i.e. 33 cm and 1 m) and either of the far measures (i.e. 4 m and 6 m). Conclusions: The vertical fusion range appears to be slightly greater at near than distance. However, the difference is not clinically significant. Measurements for distance, in a normal population, appear to be the same whether a fixation distance of 4 m or 6 m is used

Patterns of Nonlinearity in the Ratio of Stimulus Accommodative Convergence to Accommodation

Background: This study disputes the assumption that the stimulus accommodative convergence to accommodation (AC/A) ratio is linear. Subjects and Methods: Accommodative convergence induced by minus lenses of varying power (-1.50 to -6.00DS, at intervals of 1.50DS) is measured on the Synoptophore in a group of 96 non-strabismic children aged 6 years 3 months to 11 years 2 months (mean 8.81 ± 1.43 years). Results: The mean AC/A ratios obtained with a stimulus to accommodation of 1.5D; 3.00D; 4.5D; 6.00D are 2.25 ± 1.47; 2.88 ± 1.15; 3.28 ± 1.02; 3.49 ± 0.85 respectively. Five patterns of change in AC/A ratio with stiumulus are described. Conclusion: Further studies in all age groups are necessary to investigate the non-linearity of the AC/A ratio over repeated measurements and the repeatability of the testing method

Prism vergence measurements following adaptation to a base out prism

This study examines the effect of adaptation on the prism vergence range following an induced deviation. Five young adult subjects, with normal binocular functions, underwent fusional verfence testing to base in prisms before and after wearing a 10(Δ) base out Fresnel prism. The Fresnel prism was worn for a period of 2, 5, or 10 min on each of three separate occasions. The base in fusional vergence showed no statistical difference before or after adaptation, for any of the time periods. Also there was no difference in the ranges obtained over the three time periods. It was concluded that, even after a 2 min period of adaptation, fusional vergences return to a similar level as before the horizontal deviation was induced

The provision of patient information about nystagmus

Aims: The aims of this study were to evaluate the current provision of patient information about nystagmus in orthoptic clinics in the UK and Ireland and to develop a standardised information pack about nystagmus. Methods: A questionnaire was circulated to orthoptists in the UK and Ireland asking whether they had information to provide to patients with nystagmus, what was included in this information and how it could be improved. Orthoptists were also asked what should be included in a standardised information pack about nystagmus. Results: Two hundred and thirty three orthoptists completed the questionnaire. One-third of responding orthoptists did not have information to provide to patients with nystagmus. Most reported the information available to them included details of support services and physical symptoms. Including information about living with nystagmus at different ages and long-term prognosis were the most common suggestions to improve information about nystagmus. More than half of orthoptists selected all the suggested topics to be included in a standardised information pack, with support services and long-term prognosis most frequently selected. Conclusions: Only 67% of responding orthoptists had information about nystagmus to give to patients or their families. Ways to improve the current information and content considered important by orthoptists were taken into account to create a nystagmus information pack, which is now available online

Photon Statistics; Nonlinear Spectroscopy of Single Quantum Systems

A unified description of multitime correlation functions, nonlinear response functions, and quantum measurements is developed using a common generating function which allows a direct comparison of their information content. A general formal expression for photon counting statistics from single quantum objects is derived in terms of Liouville space correlation functions of the material system by making a single assumption that spontaneous emission is described by a master equation

Standardization of terminology of lower urinary tract function: pressure-flow studies of voiding, urethral resistance, and urethral obstruction

The 1988 version of the collated reports on standardisation of terminology, which appeared in Neurourology and Urodynamics, vol. 7, pp. 403–427, contains material relevant to pressure flow studies in many different sections. This report is a revision and expansion of Sections 4.2 and 4.3 and parts of Sections 6.2 and 7 of the 1988 report. It contains a recommendation for a provisional standard method for defining obstruction on the basis of pressure-flow data. 2. Evaluation of Micturition 2.1. Pressure-Flow Studies At present, the best method of analysing voiding function quantitatively is the pressure-flow study of micturition, with simultaneous recording of abdominal, intravesical and detrusor pressures and flow rate (Fig. A.1.6.1). Direct inspection of the raw pressure and flow data before, during and at the end of micturition is essential, because it allows artefacts and untrustworthy data to be recognised and eliminated. More detailed analyses of pressure-flow relationships, described below, are advisable to aid diagnosis and to quantify data for research studies. The flow pattern in a pressure-flow study should be representative of free flow studies in the same patient. It is important to eliminate artefacts and unrepresentative studies before applying more detailed analyses. Pressure-flow studies contain information about the behaviour of the urethra and the behaviour of the detrusor.This report has been produced at the request of the International Continence Society. It was approved at the twenty-fifth annual meeting of the society in Sydney, Australia

Downstream effects on human low density lipoprotein of homocysteine exported from endothelial cells in an in vitro system

A model system is presented using human umbilical vein endothelial cells (HUVECs) to investigate the role of homocysteine (Hcy) in atherosclerosis. HUVECs are shown to export Hcy at a rate determined by the flux through the methionine/Hcy pathway. Additional methionine increases intracellular methionine, decreases intracellular folate, and increases Hcy export, whereas additional folate inhibits export. An inverse relationship exists between intracellular folate and Hcy export. Hcy export may be regulated by intracellular S-adenosyl methionine rather than by Hcy. Human LDLs exposed to HUVECs exporting Hcy undergo time-related lipid oxidation, a process inhibited by the thiol trap dithionitrobenzoate. This is likely to be related to the generation of hydroxyl radicals, which we show are associated with Hcy export. Although Hcy is the major oxidant, cysteine also contributes, as shown by the effect of glutamate. Finally, the LDL oxidized in this system showed a time-dependent increase in uptake by human macrophages, implying an upregulation of the scavenger receptor. These results suggest that continuous export of Hcy from endothelial cells contributes to the generation of extracellular hydroxyl radicals, with associated oxidative modification of LDL and incorporation into macrophages, a key step in atherosclerosis. Factors that regulate intracellular Hcy metabolism modulate these effects. Copyright © 2005 by the American Society for Biochemistry and Molecular Biology, Inc