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Biomedical subjects

R A Weale

Publications and source records attributed to R A Weale.

At least 91 records · Page 5Linked to original sources
PubMed1977

A note on stray light in the Tübingen perimeter.

Measurements were made of the relative intensity of light scattered in the neighbourhood of the large and small targets on the Tübingen perimeter. Two target intensities were studied. The scattered light fraction ranged from 0-1 to 25% and its effect was detected more readily by young than by older observers.

Adult↗
PubMed1977

The Elidice: new instrument for visual acuity self-screening.

A compact electronic device which enables the user to determine for himself whether his visual acuity reaches a chosen standard has been constructed at a cost of 25 pounds. The instrument provides a test which requires the observer to respond to the orientation of a sequence of red Landolt-Cs and which takes under five minutes to complete. 'Crowding' effects associated with conventional letter charts are avoided and the test does not discriminate against astigmatic observers. One hundred observers were tested on both the new instrument (the Elidice) and a standard Snellen chart under clinical conditions. The overall agreement between the two tests was 87.8%, with the Elidice having an over-referral level of 10-7% and an under-referral level of 1-5% as compared with the letter chart. This makes the Elidice particularly suitable for the regular screening of laser users for reduced visual acuity due to macular damage.

Humans↗
PubMed1976

Ocular optics and evolution.

The application of sampling theory to image formation in the human eye is related to the population density of photoreceptors. A close numerical agreement is revealed which suggests that an image-forming device is of cardinal importance in ocular evolution.

Biological Evolution↗