Preferential looking in clinical practice: A year's experience

Abstract

SummaryPreferential Looking (PL) is now a well established laboratory method of measuring visual acuity in preverbal chilren. We have evaluated the feasibility of its routine use in clinical prac tice. We present our methods and results obtained in 80 normal children and 36 children with visual disorder and discuss the problems encountered in applying this test.

Recovery of Contour Integration in Relation to LogMAR Visual Acuity during Treatment of Amblyopia in Children

“…Contour stimuli were presented in a card format, and CDTs were measured with a staircase procedure, 30,31 described later. The contour card set comprised 15 cards.…”

Contour detection threshold: repeatability and learning with 'contour cards'

“…All participants were tested in a staircase paradigm modelled after that of Chandna et al (1988) which required a correct response for at least 2 out of 3 presentations of the same card (cards were reversed on re-presentation at random) to allow progression, with 3 reversals required to define the threshold. The observer was not masked to the contour position and subjects identified the contour when they could see it (not forced choice).…”

Preferential Looking in the mentally handicapped

“…Over the past decade Preferential Looking (PL) has been investigated in vision research labora tories as a means to determine the visual acuity of preverbal children,I.4 and is at pres ent undergoing clinical evaluation.5. 7 Preferential Looking, a behavioural tech nique, is based on the principle that a subject (usually a young child) when presented with a patterned target, such as a high contrast grati ng in a uniform featureless environment, will prefer to look at the target as long as it is within its visual resolution capabilities. The method involves the sequential presentation of gratings in an increasing order of spatial frequency until the subject appears not to see the target and acuity is determined as the finest spatial frequency which repeatedly elicits a positive response.…”

“…9 The cards were presented sequentially in an ascending or descending order of spatial frequency in a series of trials, as described in detail previously. 7 Two different staircases were used. In both, the test was initiated at the lowest spatial fre quency i.e.…”