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Biomedical subjects

E Pimm-Smith

Publications and source records attributed to E Pimm-Smith.

5 recordsLinked to original sources
PubMed1988

Visual acuity testing of young children with the Cambridge Crowding Cards at 3 and 6 m.

A modification of the single optotype Sheridan Gardiner test for pre-school children has been used to measure visual crowding. A significant 'crowding effect' has been found in children between the ages of 3 and 6 years with a general decrease in the effect over the pre-school years. The 'crowding' in 5-7 year olds is not significantly greater than that found in adults. No significant difference has been found in the extent of crowding using the test at 3 m rather than the normal 6 m viewing distance, although in general the test has been found to be practically easier with better co-operation at 3 m for the younger children. For these reasons, this particular test at 3 m would seem to be well suited to acuity testing in pre-school children, when an acuity equivalent to Snellen values is required.

Adult↗
PubMed1983

The effects of screen size and eccentricity on acuity estimates in infants using preferential looking.

The study examined whether screen size (10 degrees vs 19 degrees dia.) and separation (3 degrees vs 10 degrees eccentricity of inner edges) affect the estimates of acuity obtained with 1-3 month infants tested by forced-choice preferential looking. One and 2-month infants (but not 3-month olds) showed higher acuity estimates with the larger screens. Screen separation did not significantly affect acuity estimates for any of the age groups. Possible factors underlying these results are discussed.

Fixation, Ocular↗
PubMed1982

'Preferential looking' for monocular and binocular acuity testing of infants.

A method is described for obtaining rapid and reliable estimates of acuity in infants, for both monocular and binocular viewing. The method depends on 'preferential looking', where the infant prefers to look at a striped pattern rather than a blank screen of matched mean luminance. A staircase procedure for testing is followed, with observations being recorded by a 'blind' observer (who does not know on which of the 2 screens the striped pattern is displayed). Monocular acuity estimates have been obtained for a group of infants 3 to 4 months old with normal refractions. Many of these infants show similar acuity values in the 2 eyes, with a few showing reliable differences between the eyes. To check reliability of the method a comparison of 2 independent interleaved staircase estimates of the same eye have been made. In general this check shows highly consistent estimates for a given eye of a given infant. Nearly all infants show slightly higher acuity estimates for binocular viewing than for monocular. The possible reasons for this difference are discussed. The clinical use of such a method is reported for a number of cases. The method has been found to be useful in a variety of clinical conditions where other available tests are not possible on young infants.

Child, Preschool↗
PubMed1981

Does the Catford drum give an accurate assessment of acuity?

Adult emmetropes and myopes were tested with the Catford drum and the results compared with subjective (Landolt C) acuity. For he emmetropes the Catford drum was found to overestimate visual acuity by a factor of approximately 4. For myopes, and emmetropes viewing through plus lenses, the discrepancies were much larger. Since the Catford drum not only overestimates acuity but will do so by a factor which varies for different visual disorders, caution is needed in clinical interpretation of results obtained with it.

Adult↗