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Biomedical subjects

V M Reading

Publications and source records attributed to V M Reading.

13 recordsLinked to original sources

Self-administered automatic sight-testing. A feasibility study.

A feasibility study to estimate the extent to which self-administered computerized sight-testing instruments would be acceptable to patients and staff in a hospital outpatient eye department has been carried out. Visual acuity was measured in two ways for each of 86 patients in the age range 20-79 years; Snellen acuity was compared with the screen-based Landolt C test. The patient was seated in front of the computer controlled display, supplied with tape-recorded instructions: his/her progress was monitored without intervention unless there were obvious difficulties. The mean acuities as measured by the two methods did not differ significantly from each other, with similar variances. More than 70% of patients managed the self-administered test without any help at all, only 4-5% failing completely. The computerized test was favoured by most except the oldest patients. It forms therefore a sound basis for further development on a large scale.

Adult

A new analysis of United Nations mortality statistics.

Demographic data published by the United Nations in 1987 are analysed in terms of the Gompertz function. Projections for maximum life spans are obtained, with the data broadly divisible into three clusters. These are attributable not only to the influence of high infant mortality, but suggest also constitutional and/or environmental variations among members of the clusters. The difference between life span and life expectancy is estimated analytically. A comparison with an earlier analysis supports the view that there are important differences between the life expectancies of the sexes.

Adult

Significance of the t-test applied to ocular measures.

An example, drawn from some photokeratometric measurements, is used to illustrate the use and misuse of statistical tests of significance on biomedical data. The type of test which must be applied is governed by whether or not inherent pairing exists between the variables. The possible consequences of using a method which erroneously assumes independence of the two samples is examined.

Adult

Astigmatism following cataract surgery.

The changes in corneal curvature were determined at regular intervals over a one-year period following intracapsular cataract extraction by microsurgical techniques. During the first postoperative month photokeratometric measurements showed rapid changes in astigmatism associated with large changes in the direction of the axis. Thereafter astigmatism against-the-rule predominated. Data from the small group of patients who underwent surgery in which the technique of phacoemulsification was used show that the smaller changes in corneal curvature are attributable to the smaller incision size and reduced number of sutures. With patients who underwent intracapsular extraction a comparison has been made between the effects of large and small section sizes, and a procedure is outlined whereby surgically induced astigmatism may be minimised.

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