Changes in the axis of astigmatism: a longitudinal study.

Changes in the axis of astigmatism have been followed up in the same individuals over several decades. Only a proportion of subjects with direct astigmatism in their youth change to inverse astigmatism by way of oblique astigmatism.

A longitudinal study of the age dependence of human ocular refraction--III. The mediation of changes from direct to inverse astigmatism examined by means of matrices of transition probabilities.

This study enquires into the manner in which the axis of astigmatism changes in the course of individual refractive histories. Specifically, two related problems are addressed: (1) how is the change from direct to inverse astigmatism mediated, and (2) what is the range of relative proportions of each of four variables (spherical ametropia, direct, inverse and oblique astigmatism) that occur in a sample population so that it can be considered randomly sampled and well distributed? Solutions to both problems are obtained by calculation of the probabilities with which transitions between such variables occur. A moderately sized longitudinal sample is used to demonstrate the new method.

Changes in the orientation of the axis of astigmatism associated with age.

A new regression equation for the change in the axis of astigmatism with age, as deduced from cross-sectional studies, is presented. Possible artefacts arising from the methods used to obtain mean prescriptions are discussed; it is shown that these may result in over-estimation of the occurrence of oblique cylinders in middle-age and that a previously demonstrated gradual change of orientation of the axis of astigmatism may have no basis in reality. The need for further longitudinal studies is emphasized.

A longitudinal study of the age dependence of human ocular refraction--II. Prediction of future trends in medium and high myopia by means of cluster analysis.

A sample population of myopes with an initial correction of 2 DS or more is extracted from the longitudinal sample of ametropes reported by Saunders (1986). The myopes are partitioned by means of cluster analysis and, as a result, three distinct groups of myopes are identified. The time/regression equations which best describe the groups are stated.

A longitudinal study of the age-dependence of human ocular refraction--I. Age-dependent changes in the equivalent sphere.

Following on from a cross-sectional analysis of refraction data (Saunders, 1981), the present paper attempts the evaluation of serial recordings of a new sample of refractive corrections using longitudinal methods. This study compares the results of the cross-sectional and longitudinal methods, investigates whether or not the latter supports the conclusions of the former, examines to what accuracy this is achieved and, where the results differ, seeks a reason for this. It is demonstrated that in spite of such differences the two methods coincide in their conclusions.

Prognosis of refractive corrections.

The validity and efficacy of the prognosis equation published by Saunders (1984b) is tested against previously reported longitudinal data. In a fair and random sample and over a short interval, nearly 60% of the sample was found to have a prediction error of less than 0.25 DS and, in 92%, the error involved was less than 0.

Transformation of sphero-cylinders. I. Ranking procedure.

Parametric statistical analysis requires a rule by which the variates are quantitatively ranked. In this study an isomorphic transformation of sphero-cylinders is developed and two alternative ranking hierarchies for the sphero-cylinder are proposed.

The algebra of sphero-cylinders.

Sphero-cylinders are shown to be representable by formal vectors. An algebra applicable to sphero-cylinders is stated and mathematically consistent operations are defined. Examples of practical applications of some operations are given.

The astigmatic modulus and its age-dependence.

The question is posed as to why the modulus of the astigmatic vector appears to be randomly distributed with age. This paper investigates astigmatic population distributions. On the assumption of statistical independence, the expected probabilities are determined and compared with the observed values.

Markers of epidermal differentiation expressed by rat keratinocytes cultured by a modified feeder layer technique.

A broad range of analytical methods has been used to investigate the expression of key differentiation markers in keratinocytes cultured by a modified feeder layer technique. Cultures were stratified and showed many of the features characteristic of epidermal differentiation in vivo including tonofilaments, desmosomes, loss of organelles and thickening of the plasma membrane to form the cornified envelope. Profilaggrin synthesis was detected by 32P-incorporation and the presence of filaggrin suggested that it was broken down by the normal route.

Use of spinal traction in the treatment of neck and back conditions.

Spinal traction is a time-honored method for the treatment of disc protrusion, degenerative disc disease, and joint dysfunction. Effective treatment is not as easy or as simple to administer as it may appear. Many variations of technique exist, some of questionable value.

Fibronectin in cultured rat keratinocytes: distribution, synthesis, and relationship to cytoskeletal proteins.

The aim of this study was to investigate whether epidermal cells can synthesise fibronectin and whether the distribution of this glycoprotein is related to the adhesion and cytoskeletal organisation of these cells. The production of fibronectin by newborn rat epidermal cells was shown by indirect immunofluorescence staining of cultures grown in the absence of a feeder layer using an antiserum which had been cross-adsorbed with foetal calf serum proteins to remove antibodies which recognised serum fibronectin. The distribution of fibronectin in areas of cell-cell and cell-substratum contact, characteristically in the form of short radial stitches, was examined in more detail using immunoelectron microscopy with colloidal gold as marker.

The possible correlation of intra-ocular pressure and the volume of the anterior chamber.

An investigation is made into the correlation between anterior chamber volume and intra-ocular pressure. It is suggested that patients can be screened for possible ocular hypertension by measuring their corneal radii and the depth of their anterior chamber. A nomogram shows which combinations of the parameters may lead to ocular hypertension and thus indicates which patients need to be investigated at greater length.

Unilateral lumbar traction.

Unilateral lumbar traction has been theorized to be superior to bilateral lumbar traction in certain cases. Many patients who cannot tolerate bilateral lumbar traction are comfortable with this method. It enables the physical therapist to administer lumbar traction to patients with protective scoliosis who would otherwise be unable to tolerate treatment.

Synthesis and hypoglycemic activity of pyridyl alcohols.

The potent hypoglycemic activity of 3-(3-methyl-2-pyridyl)propan-1-ol (1) prompted us to synthesize and study related structures. Some of the variables studied were the position of the methyl and alcohol side chains, the distance between the heterocyclic ring and the hydroxyl group, the effect of additional nuclear substitution, and the effects of branching and substitution on the alcohol side chain. The compounds were tested in 48-h fasted rats, usually at a dose of 150 mg/kg po.

Lumbar traction*.

The aim of this article is to present and discuss: 1) types of lumbar traction; 2) effects of lumbar traction; 3) indications and contraindications for lumbar traction; 4) effective lumbar traction techniques. There is a review of important points that have been presented in earlier literature, as well as the introduction of new ideas and concepts. A portion of this article deals with the rationale-of using lumbar traction for the treatment of herniated disc and other lumbar spinal nerve root syndromes.

Classification of musculoskeletal spinal conditions*.

The aim of this article is to present and discuss the classification of musculoskeletal spinal conditions. The major classifications presented are muscle, joint, and nerve root. Many different conditions are presented under each of these major classifications with emphasis on those conditions commonly seen in a physical therapy clinic.