Purchase this article with an account.
V. Manjunath, I. Serrano-Pedraza, O. Osunkunle, J. C. A. Read, M. P. Clarke; Suppression is Demonstrable During Ocular Alignment in Intermittent Exotropes. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1828.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To investigate the characteristics of suppression in intermittent exotropia
Twelve subjects with intermittent exotropia and twenty age matched subjects with normal binocular alignment were studied. Stereoacuity was measured using polarised images projected onto a screen at 120 centimetre viewing distance.Subjects had to comment on whether a punched-out circle of dots in a random-dot stereogram was in front of or behind the screen. Suppression was then looked for by presenting a pair of images of toys or cartoons which were viewed through polarizing glasses at a distance of 120 centimetres. A scene of binocularly-viewed foliage surrounding a dichoptic butterfly/net image was used to confirm ocular alignment before each trial.The cartoon faces (6 x6deg, 400 millisec duration) were presented with binocular disparity, one image presented at the fovea of one eye and the other image presented at a varying distance from the fovea horizontally, either in the temporal or nasal retina of the fellow eye. Subjects had to indicate whether they saw one or two faces.
Stereoacuity ranged from 8.1 to 0.15 arcmin in normal subjects and 3.7 to 0.2 arcmin in intermittent exotropes. Retinal image disparity of more than 6 degrees either nasally or temporally led to diplopia in normal subjects. Ten of twelve intermittent exotropes demonstrated suppression when the non-foveal image was presented to the temporal, but not nasal, retina, even though the eyes were aligned.
Intermittent exotropes demonstrate interocular suppression, triggered by information presented to the temporal retina not only when exotropia is manifest but also when the eyes are aligned.
This PDF is available to Subscribers Only